PATENT DOCUMENT

Publication Number: US-11296381-B2
Application Number: US-201916259584-A
Country: US
Kind Code: B2

Title: High-density battery pack

Abstract:
Battery packs are presented. The battery packs include a plurality of cell blocks, each cell block comprising a plurality of battery cells. The battery pack also includes a plenum chamber configured to fluidly couple each of the cell blocks to an exterior of the battery pack in response to a thermal event in the battery cell in a separate cell block. In some embodiments, at least one of the cell blocks is configured to be fluidly coupled to the plenum structure via a cell block vent.

Claims:
What is claimed is: 
     
       1. A battery pack comprising:
 a plurality of cell blocks each containing at least two battery cells, the plurality of cell blocks including a first cell block and a second cell block; 
 a plate, wherein each cell block comprises a vent facing the plate; and 
 a lateral member coupled to the plate between the first cell block and the second cell block, the lateral member comprising:
 a first wall facing the first cell block, wherein the lateral member defines a first port in the first wall, and 
 a second wall facing the second cell block, wherein the lateral member defines a second port in the second wall, and wherein the lateral member comprises an internal conduit between the first wall and the second wall; 
 
 wherein the plurality of cell blocks, the lateral member, and the plate at least partially define a volume inside the battery pack, wherein the lateral member separates the volume into a first chamber between the plate and a vent of the first cell block, wherein the lateral member separates the volume into a second chamber between the plate and a vent of the second cell block, and wherein a lateral flow path is defined between the first chamber and the second chamber through the first port, the internal conduit, and the second port in the lateral member. 
 
     
     
       2. The battery pack of  claim 1 , wherein the plurality of cell blocks comprises:
 a first row of cell blocks comprising a first subset of the plurality of cell blocks, and 
 a second row of cell blocks comprising a second subset of the plurality of cell blocks; and 
 wherein the lateral member is positioned between the first row of cell blocks and the second row of cell blocks. 
 
     
     
       3. The battery pack of  claim 1 , wherein the internal conduit of the lateral member defines at least one directional change in a fluid path through the internal conduit of the lateral member. 
     
     
       4. The battery pack of  claim 3 , wherein the at least one directional change equals or exceeds 90 degrees. 
     
     
       5. The battery pack of  claim 1 , wherein the internal conduit comprises a screen configured to inhibit flow of solid material through the internal conduit. 
     
     
       6. The battery pack of  claim 1 , wherein the volume mitigates effluents of the cell blocks before delivering the effluents to a battery pack vent towards the exterior of the battery pack. 
     
     
       7. The battery pack of  claim 1 , wherein at least four battery cells are disposed within each cell block of the plurality of cell blocks. 
     
     
       8. The battery pack of  claim 1 , wherein each cell block comprises at least two abutting prismatic battery cells. 
     
     
       9. The battery pack of  claim 1 , wherein the volume is configured to separate at least a portion of solid matter from effluents of a battery cell as the effluents flow toward the exterior of the battery pack. 
     
     
       10. The battery pack of  claim 9 , wherein the volume is configured to mitigate effluents of the battery cell by reducing a temperature of the effluents as the effluents flow between the battery cell and the exterior of the battery pack. 
     
     
       11. The battery pack of  claim 1 , wherein the cell block is sealed when the cell block is below a threshold internal pressure. 
     
     
       12. The battery pack of  claim 11 , wherein each cell block vent is configured to open and direct effluents of the battery cells of a cell block towards the volume when the cell block reaches the threshold internal pressure. 
     
     
       13. The battery pack of  claim 1 , wherein each cell block comprises an insulation material disposed between a structure of the cell block and at least one battery cell of the cell block.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Patent Application No. PCT/US2017/044474, filed Jul. 28, 2017, which claims the benefit of U.S. Application Ser. No. 62/368,789, filed Jul. 29, 2016, and U.S. Application Ser. No. 62/509,468, filed May 22, 2017, the disclosures of which are hereby incorporated by reference in their entirety for all purposes. 
    
    
     FIELD 
     This disclosure relates generally to battery structures, and more particularly to battery packs. 
     BACKGROUND 
     Tight placement of battery cells within a battery pack increases overall energy density of the pack but can impact behavior of the pack under abuse conditions. 
     SUMMARY 
     In some embodiments, a battery pack includes a plurality of cell blocks, each cell block comprising a plurality of battery cells. The battery pack also includes a plenum structure configured to fluidly couple each of the cell blocks to an exterior of the battery pack in response to a thermal event in a battery cell in a separate cell block. In some instances, at least one of the cell blocks is configured to be fluidly coupled to the plenum structure via a cell block vent. In further instances, the cell block vent includes a backflow prevention mechanism configured to impede discharged matter from entering the cell block from the plenum structure, and permit discharge of matter from within the cell block into the plenum structure. 
     In some variations, the plenum structure includes a plurality of plenum chambers coupled together. In these variations, the battery pack includes a first battery module and a second battery module. The first battery module includes a plurality of cell blocks configured to be fluidly coupled to a first plenum chamber, and a second battery module including a second plurality of cell blocks configured to be fluidly-coupled to a second plenum chamber. In certain instances, a lateral member is disposed between the first battery module and the second battery module. The lateral member may include an internal conduit extending from a first port on a first end of the lateral member to a second port on a second end of the lateral member. 
     In some embodiments, a battery structure includes a battery pack housing that houses a plurality of battery cells. One or more of the battery cells has a battery cell vent that is shaped to direct discharge outward from the battery cell during thermal runaway. For example, a battery cell vent can be located on a side of the battery cell opposite a terminal of the battery cell. 
     In some embodiments, the battery cell vents can be fluidly-coupled with one or more battery pack vents. The battery pack vents facilitate discharge of matter from one or more battery cells towards an exterior of the battery pack housing. In some examples, the battery pack housing is structured so that battery cell vents are aligned with one or more battery pack vents. In some examples, the battery pack includes a conduit that fluidly-couples one battery pack vent to one battery cell vent. In some examples, the battery pack includes a manifold that fluidly-couples a battery pack vent to two or more battery cell vents. In some variations, the pack vent is fluidly-coupled to one cell vent and has an interface therewith. A seal is disposed along the interface. In some variations, the battery pack includes an integrated vent having a first portion and a second portion. The first portion includes one cell vent and the second portion includes one pack vent. 
     In other variations, a plate structure is coupled with the battery pack structure to form a plenum chamber. The plate structure includes at least one flow guide and at least one occluding member. The at least one flow guide and the at least one occluding member operate, during the thermal runaway event, to facilitate flow of vapor released from the cell vents towards a plenum vent to an external ambient environment and impede flow of battery material discharged from the cell vents towards the plenum vent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings. 
         FIG. 1A  is a perspective view of a battery pack, in accordance with an illustrative embodiment; 
         FIG. 1B  is a detail view, shown in cross-section, of a portion of the battery pack of  FIG. 1A , in accordance with an illustrative embodiment; 
         FIG. 1C  is a cross-sectional view of a first cell block and a second cell block in a battery pack, in accordance with an illustrative embodiment; 
         FIG. 1D  is a perspective view of a cell block vent, in accordance with an illustrative embodiment; 
         FIG. 1E  is a schematic cross-section of the cell block vent of  FIG. 1D , showing laser cutting of the cell block vent, in accordance with an illustrative embodiment; 
         FIG. 1F  is a schematic cross-section of the cell block vent of  FIG. 1D  having a seal that includes a sealing compound, in accordance with an illustrative embodiment; 
         FIG. 1G  is a schematic cross-section of the cell block vent of  FIG. 1D  having a seal that includes a thin polymeric material, in accordance with an illustrative embodiment; 
         FIG. 1H  is a schematic cross-section of a cell block vent having a seal that includes a gasket, in accordance with an illustrative embodiment; 
         FIG. 2A  is a schematic diagram, shown in a top plan view, of a portion of a battery pack, in accordance with an illustrative embodiment; 
         FIG. 2B  is a perspective view of a first side of a lateral member, in accordance with an illustrative embodiment; 
         FIG. 2C  is a perspective view of a second side of the lateral member of  FIG. 2B , in accordance with an illustrative embodiment; 
         FIG. 2D  is a cross-sectional view of a lateral member that includes a throughway therethrough, in accordance with an illustrative embodiment; 
         FIG. 2E  is a perspective view, shown in cross-section, of the throughway of  FIG. 2D , in accordance with an embodiment; 
         FIG. 2F  is a perspective view of a cell block disposed between a first lateral member and a second lateral member, in accordance with some embodiments; 
         FIG. 3A  is a schematic diagram of a testing apparatus that includes a cell block and a plenum chamber, in accordance with an illustrative embodiment; 
         FIG. 3B  is a graph of temperatures measured by the testing apparatus of  FIG. 3A ; 
         FIG. 4A  illustrates a portion of a battery pack, in accordance with an illustrative embodiment; 
         FIG. 4B  illustrates a portion of a battery pack, in accordance with an illustrative embodiment; 
         FIG. 4C  illustrates a portion of a battery pack, in accordance with an illustrative embodiment; 
         FIG. 4D  illustrates a portion of a battery pack, in accordance with an illustrative embodiment; 
         FIG. 5A  is a schematic cross-section diagram of a system for directing discharged matter from battery cells, in accordance with an illustrative embodiment; 
         FIG. 5B  is a top view of a plate structure described with reference to  FIG. 5A , in accordance with an illustrative embodiment; 
         FIG. 5C  is a top view of a plate structure described with reference to  FIG. 5A , in accordance with an illustrative embodiment; 
         FIG. 6  illustrates an exploded view of an exemplary battery module, in accordance with an illustrative embodiment; 
         FIG. 7A  is a partial view of the exemplary battery module of  FIG. 6 , in accordance with an illustrative embodiment; 
         FIG. 7B  is a partial view of an exemplary battery module, in accordance with an illustrative embodiment; 
         FIG. 7C  is a schematic end view of an exemplary bus bar seal, in accordance with an illustrative embodiment; 
         FIG. 7D  is a schematic end view of an exemplary bus bar seal, in accordance with an illustrative embodiment; and 
         FIG. 8  is an exploded view of an exemplary battery pack, in accordance with an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to exemplary embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
       FIG. 1A  depicts a perspective view of a battery pack  100 , in accordance with an illustrative embodiment. The battery pack  100  has cell blocks  102  arranged in lateral rows, each lateral row defining a battery module  104 . Adjacent battery modules  104  are separated by lateral members  106 , which can also function as load-bearing members within the battery pack  100 . Within each battery module  104 , the cell blocks  102  may be electrically-coupled in series, in parallel, or some combination thereof. The battery pack  100  may optionally include one or more pack vents  108  that fluidly-couples the cell blocks  102  to an exterior of the battery pack  100 . For example, battery pack  100  may include a pack vent on each end of battery pack  100 . 
     Pack vents  108  may be incorporated within modules associated with a front panel  107  and/or a rear panel  109  of the battery pack structure. Front panel  107  and rear panel  109  may be end panels that at least partially define a perimeter of the battery pack  100 . The end panels may be coupled with side rails  111 ,  113  to fully define an outer perimeter of the battery pack  100 . Side rails  111 ,  113  may provide structural rigidity to the battery pack  100  and may be configured to support battery modules  104  within the pack. The end panels and side rails may be made of any number of materials including aluminum, steel, composites, plastics, alloys, or other materials that may provide weight and/or robustness to the structure of battery pack  100 . 
     Each cell block  102  includes a plurality of battery cells  110  disposed therein, although each cell block may also contain a single battery cell  110 . The plurality of battery cells  110  may be electrically-coupled in series, in parallel, or some combination thereof. In  FIG. 1A , four battery cells  110  are depicted within each cell block  102 . However, this depiction is not intended as limiting. Any number of battery cells  110  can be placed in each cell block  102 . Moreover, the number of battery cells  110  in each cell block  102  need not be the same. Different numbers of battery cells  110  are possible for each cell block  102 . 
     It will be appreciated that the cell blocks  102  represent a unit for containing thermal runaway between cells within the battery pack. Should a thermal runaway event occur, the thermal runaway event will be limited to batteries in a particular cell block  102 . If a single battery cell  110  fails, other battery cells  110  within a particular cell block  102  in the battery pack  100  will be exposed to rapid heating. The thermal runaway of a single battery cell (and effects thereof) is limited to the battery cells  110  within a cell block. 
     Turning now to  FIG. 1B , a detail view is shown, in cross-section, of a portion of the battery pack  100  of  FIG. 1A . The detail view is perpendicular to a lateral direction of the battery modules  104  (see dashed lines and arrows in  FIG. 1A ). Each cell block  102  includes a corresponding cell block vent  112 , which is oriented towards a plate structure  114  of battery pack  100 . The cell block vents  112  are operable to open during a thermal runaway event, thereby allowing matter to discharge from their respective cell blocks  102 . Matter discharged from a cell block  102  may result from one or more battery cells  110  overheating (i.e., battery cells  110  within the cell block  102 ). Such matter can include solid materials such as battery electrolyte materials, separator materials, and electrode materials. Such matter can also include gaseous matter, such as vapors resulting from a decomposition of battery materials, or the burning of electrolyte, separator, and/or electrode materials. 
     During opening of a cell block vent  112 , the plate structure  114  may receive and redirect matter discharged from a corresponding cell block  102 . However, the cell block vent  112  may be configured to redirect matter being discharged out of its respective cell block  102 . For example, and without limitation, the cell block vent  112  may form a flow guide upon opening. The cell block vent  112  may also be configured to inhibit or prevent matter from entering a neighboring cell block. 
     Further, cell block vent  112  may be configured to allow only an outward flow of matter (i.e., flow from an interior of a cell block  102  to its exterior). In some embodiments, the cell block vents  112  include a backflow prevention mechanism. The backflow prevention mechanism is configured to impede discharged matter from entering a cell block  102 , yet permit discharge of matter from within the cell block  102 . 
     The cell block vent  112  can be manufactured as an integral portion of its corresponding cell block, or alternatively, manufactured separately therefrom. In the latter case, the cell block vent  112  may be coupled to a cell block via adhesive, welding, one or more mechanical fasteners, or any combination thereof. Additionally, cell block vents may be coupled with the cell block structure via a polymeric membrane or other polymeric material. The polymeric material may be configured to weaken, break, or fail as a surrounding environmental temperature exceeds a threshold, which may be associated with, for example, delivery of vented material from one or more cells of a cell block. 
     In various embodiments, the cell block vent  112  can include (or be formed of) a dielectric material. The dielectric material may provide electrical insulation, thereby providing back-up protection against electrical shorts. Non-limiting examples of the dielectric material include aluminum oxide materials, silicon dioxide materials, polytetrafluoroethylene materials, and polyimide materials. 
     Now turning to  FIG. 1C , a cross-sectional view is presented of a first cell block  150  and a second cell block  152 , in accordance with an illustrative embodiment. The first cell block  150  and the second cell block  152  are analogous to those described in relation to  FIGS. 1A-1B . In the embodiment of  FIG. 1C , the first cell block  150  and the second cell block  152  are separated by lateral members  154  on each side that support the cell blocks  150 ,  152  above a plate structure  156 . Such support allows a gap to form, thereby forming a volume into which effluents (discharged matter and gasses) from cell blocks can flow when their respective cell vents open. As illustrated, this volume includes first and second chambers  158  and  160  separated by lateral member  154 . The first cell block  150  and the second cell block  152  include corresponding cell block vents  162  and  164  for discharging matter. Chambers  158  and  160  may be referred to as plenum chambers, and the volume formed by at least chambers  158  and  160  may be referred to as a plenum structure. 
       FIG. 1C  depicts the first cell block  150  directing matter in a particular direction. The first cell block  150  may discharge matter into the first plenum chamber  158  (see arrows), which sits at a lower pressure than the first cell block  150  (e.g., at atmospheric pressure). The cell block vent  162  redirects matter discharged from the first cell block  150 , thereby preventing such discharged matter from directly impinging upon the plate structure  156 . The discharged matter dissipates energy by expanding within the first plenum chamber  158 . The first plenum chamber  158  may be defined from below by the plate structure  156 , which may partially define the plenum chamber, and may additionally provide structural protection for the battery pack from below. 
     With further reference to  FIG. 1C , matter discharged through the cell block vent  162  is redirected to flow within the first plenum chamber  158 , which may involve a lateral flow (i.e., flow parallel to the lateral members  154 ). In  FIG. 1C , lateral flow occurs along directions into and out of the cross-sectional view. Re-direction of matter so-discharged may be aided by the plate structure  156 , the cell block vent  162 , or both. In certain instances, the discharged matter (or portions thereof) may enter one or more ports disposed along sides of the lateral members  154  (i.e., lateral members  154  adjacent the first plenum chamber  158 ). 
     Matter discharged through the cell block vent  162  may include vapors, gases, char, electrolyte fluid, and solid matter. Solid matter can include solid battery material such as cathode active material, anode active material, separator material, and so forth. In this capacity, the cell block vent  162  may allow for a rapid reduction of pressure within the first cell block  150  (or battery cells therein) by transferring discharged matter from the cell block  150  into the first plenum chamber  158 . This transfer may also reduce a temperature of the cell block  150  (or battery cells therein). 
     It will be appreciated that the cell block vents  112 ,  162 , and  164  of  FIGS. 1A-1C  may be configured to regulate flows of discharged matter, including guiding such flows into a plenum chamber.  FIG. 1D  presents a perspective view of one such embodiment. The cell block vent  180  includes a trap door  182  that has been cut into a sheet of material  184  (e.g. a metal sheet such as aluminum or steel). Uncut portion  186  serves as a bendable joint. Under ordinary operation, cell block vent  180  remains closed. When pressure builds within the cell block, trap door  182  opens into a canted position. The canted position may create an exit gap at least 2 mm relative to the sheet of material  184 , as measured at an end opposite the uncut portion  186 . The canted position allows the opened trap door  182  to function as a flow guide, changing a direction of matter discharged during the thermal runaway event. In certain instances, this change in direction prevents matter from impinging perpendicularly onto an object (e.g., impinging perpendicularly onto the plate structure  114  of  FIGS. 1A &amp; 1B ). 
     The cell block vent  180  is also configured to prevent an inward flow of matter. An outer edge  188  of the “trap door”  182  mates with an inner edge  190  of the sheet of metal  184  via beveled surfaces. These beveled surfaces establish a perimeter that shrinks along a first direction perpendicular to the sheet of metal  184 . However, along a second direction opposite the first, the perimeter expands. Thus, the “trap door”  182  is blocked from motion along the first direction, but can open along the second direction. 
     In  FIG. 1D , the “trap door”  182  is depicted as blocked from motion above the sheet of metal  184 , but can open below the sheet of metal  184 . However, this depiction is not intended as limiting. The cell block vent can be formed from a portion different than its corresponding cell block. 
     In some variations, the cell block vent  180  can be formed into a cell block by stamping, cutting, laser ablation, or a combination thereof. For example, and without limitation, the cell block vent  180  may be formed using a laser to ablate a bevel cut (e.g., 45°) into the sheet of metal  184 , which may correspond to a portion of a cell block. 
       FIG. 1E  presents a schematic cross-section of a portion of the cell block vent  180  of  FIG. 1D , in accordance with an illustrative embodiment. The portion of the cell block vent  180  includes the sheet of metal  184  and the “trap door”  182 . A laser  191 , which is angled relative to the sheet of metal  184 , cuts a bevel in the sheet of metal  184  to form the “trap door”  182  along the plane of the dashed line. Displacement of the laser  191  relative to the sheet of metal  184  allows the laser  191  to cut the sheet of metal  184  continuously. 
     It will be appreciated that the cell block vent  180  may include a seal, such as a seal to occlude a cut in the sheet of metal  184 .  FIG. 1F  presents a schematic cross-section of the cell block vent  180  of  FIG. 1D , but in which the cell block vent  180  has a seal  192  formed by a sealing compound  193 , in accordance with an illustrative embodiment. The sealing compound  193  is disposed in a gap between the trap door  182  and the sheet of material  184 . The seal  192  formed by the sealing compound  193  may have a thickness measured along a distance that extends from the outer edge  188  of the “trap door”  182  to the inner edge  190  of the sheet of metal  184 . The distance may be oriented perpendicular to surfaces of the outer edge  188  and the inner edge  190 . 
     In some instances, the sealing compound thickness is at least 0.0005 in. In some instances, the thickness is at least 0.001 in. In some instances, the thickness is at least 0.002 in. In some instances, the thickness is at least 0.003 in. In some instances, the thickness is at least 0.004 in. In some instances, the thickness is no greater than 0.005 in. In some instances, the thickness is no greater than 0.004 in. In some instances, the thickness is no greater than 0.003 in. In some instances, the thickness is no greater than 0.003 in. In some instances, the thickness is no greater than 0.001 in. 
     The upper and lower limits of the thickness may be combined in any variation as above to define a range. For example, and without limitation, the thickness may be at least 0.002 in. but no greater than 0.004 in. In another non-limiting example, the thickness may be at least 0.0005 in. but no greater than 0.005 in. Other ranges are possible. 
     It will be understood that the seal of the cell block vent  180  is not necessarily limited to a sealing compound.  FIG. 1G  presents a schematic cross-section of the cell block vent  180  of  FIG. 1D , but in which the cell block vent  180  has a seal  194  formed by a thin polymeric material  195 , in accordance with an illustrative embodiment. The thin polymeric material  195  may be a film or layer. The thin polymeric material  195  is coupled to the sheet of metal  184 , which, in some instances, can include a pressure-sensitive adhesive material. The pressure-sensitive adhesive material may allow the seal  194  to fail at a pressure, thereby allowing trap door  182  to open outward (e.g., downward in the exemplary orientation of  FIG. 1G ). In some instances, the failure pressure can be pre-selected, for example based on the pressure-sensitive adhesive material, used, thickness thereof, and other variables. 
     The seal of the cell block vent  180  may also include a gasket.  FIG. 1H  presents a schematic cross-section of the cell block vent  180  of  FIG. 1D , but in which the cell block vent  180  has a seal  196  formed by a gasket  197 . The gasket  197  may include an elastomeric material (e.g., neoprene, silicone rubber, fluoropolymer elastomer, etc.). In some instances, the gasket  197  may be supported by a battery pack structure  198 , which can serve to define part of a plenum and include a trap door  182 . The gasket  197  may also be used in conjunction with other types of seals. For example, and without limitation, a thin polymer film  199  may be disposed over the trap door  182  and adjacent the gasket  197 . 
     In some embodiments, cell block vents can be recessed within their respective cell blocks.  FIG. 1H  depicts such an embodiment. Cell block vent  180  is in a recessed configuration and has a portion shared in common with the battery pack structure  198 . However, this depiction is not intended as limiting. Other configurations are possible (e.g., protruding). Moreover, the cell block vent  180  may be entirely separate from the battery structure  198 . Such configurations may improve protection of cell block vents from discharges of neighboring cell blocks. 
     In general, a seal of a cell block vent may function as an environmental seal protecting an interior of the cell block from water, dust intrusion, and so forth. The seal may also protect the interior of the cell block from vent gasses generated by neighboring cell blocks (i.e., during thermal runaway of the neighboring cell blocks). The seal may additionally serve as a predetermined point of failure, allowing the cell block vent  180  to open at low pressures (i.e., less than 20 psi). Depending on a design of the cell block, such low pressures may avoid excessive stresses from building up within the cell block during thermal runaway. 
     In some embodiments, the seal fails at a pressure no greater than 20 psi. In some embodiments, the seal fails at a pressure no greater than 15 psi. In some embodiments, the seal fails at a pressure no greater than 10 psi. In some embodiments, the seal fails at a pressure no greater than 5 psi. In some embodiments, the seal fails at a pressure no greater than 2.5 psi. In some embodiments, the seal fails at a pressure no greater than 1.5 psi. 
     In some embodiments, the seal fails at a pressure of at least 0.5 psi. In some embodiments, the seal fails at a pressure of at least 1.5 psi. In some embodiments, the seal fails at a pressure of at least 2.5 psi. In some embodiments, the seal fails at a pressure of at least 5 psi. In some embodiments, the seal fails at a pressure of at least 10 psi. In some embodiments, the seal fails at a pressure of at least 15 psi. 
     The upper and lower limits of the pressure may be combined in any variation as above to define a range. For example, and without limitation, the seal may fail at a pressure from 1.5 to 5 psi. In another non-limiting example, the seal may fail at a pressure from 2.5 to 10 psi. Other ranges are possible. 
     In some variations, the seal, such as the seal  194  in  FIG. 1G  and the seal  196  in  FIG. 1H , may have a seal length equivalent to a length of cut in a sheet of metal that forms a “trap door”. A ratio of door area to seal length may influence an opening pressure for the “trap door”. The door area is determined by dimensions of the “trap door” (i.e., size and shape). As such, this ratio can be selected to match a pressure requirement for the cell block. For example, and without limitation, a circular configuration for a “trap door” can have a lower opening pressure than a long, thin configuration. In a further non-limiting example, the circular configuration has the lowest opening pressure and the long, thin configuration has the highest opening pressure. 
     Referring again to  FIG. 1B , the lateral members  106  suspend the battery modules  104  (or cell blocks  102 ) above the plate structure  114  to establish a gap  116  therebetween. The gap  116  helps define a plenum chamber  118  below each battery module  104 . The plenum chamber  118  represents a partitioned volume within the battery pack  100 . Such partitioning limits a supply of freely-available oxygen within the plenum chamber  118 . Thus, an amount of oxygen in the plenum chamber  118  may be inadequate to support ignition, or alternatively, may be sufficient to support only partial ignition. 
     In one aspect, the plenum chamber  118  can receive discharges of matter from an adjacent battery module  104 . These discharges are regulated by the cell block vents  112 . Without wishing to be limited to a particular mechanism or mode of action, the cell block vents  112  may open in response to a pressure differential between the cell block  102  and the plenum chamber  118 . For example, when pressure within a cell block achieves a higher pressure than the pressure in the plenum chamber, a corresponding cell block vent may open to allow matter from the cell block  102  to discharge into the plenum chamber  118 . In some variations, lateral members  106  may include an internal conduit  120  to fluidly couple ports disposed on opposite sides thereof. The internal conduit  120  may allow fluid communication between plenum chambers  118  adjacent the opposite sides. Such fluid communication may allow matter discharged into one plenum chamber to traverse a lateral member  106  and flow into the other plenum chamber. 
       FIG. 2A  presents a schematic diagram, shown in a top plan view, of a portion of a battery pack  200 , in accordance with an illustrative embodiment. The battery pack  200  may be analogous to the battery pack  100  of  FIG. 1A . However, for purposes of illustration, some components of the battery pack  200  have been omitted. The battery pack  200  includes a plurality of lateral members  202  disposed on (or coupled to) a plate structure  204 . Each lateral member  202  includes ports  206  that are fluidly coupled to each other by an internal conduit  208 . An exemplary cell block  210  is shown in  FIG. 2A . Cell block  210  may be analogous to the cell blocks  102  described in relation to  FIGS. 1A-1C . 
     The lateral members  202  enhance mechanical strength and rigidity of the battery pack  200 . The lateral members  202  also establish a tortuous pathway that impedes propagation of discharged matter (from one or more cells) through the battery pack  200 , thereby reducing the amount of discharged matter exiting the battery pack  200 . For example, and without limitation, one or more changes in direction along the tortuous path helps in separating particulates, such as hot or molten debris, from gaseous components in the discharged matter through inertial separation. The tortuous pathway also lengthens the distance through which discharged matter must propagate before exiting battery pack  200 , which can reduce the temperature of any discharged matter that exits battery pack  200 . 
     In the example of  FIG. 2A , the lateral members  202  are beams of aluminum formed by extrusion or beams of stamped steel. The beams include void spaces or perforations that, in addition to providing weight savings, also contribute to the tortuous pathway. In another non-limiting example, the lateral members  202  may include screens or meshes within a flow path defined by void spaces therein (e.g., internal channels or conduits). It will be appreciated that such features may increase a structural surface area exposed to discharged matter flowing through the tortuous pathway. By doing so, the lateral members  202  improve heat removal from the discharged matter. Improved heat removal may be beneficial in embodiments where the battery pack  200  exhausts the discharged matter out of a pack vent. 
       FIGS. 2B &amp; 2C  present perspective views of, respectively, a first side  232  and a second side  234  of a lateral member  230 , according to an illustrative embodiment. The lateral member  230  may be analogous to lateral members  106 ,  154 ,  202  described in relation  FIGS. 1A-1C &amp; 2A . The first side  232  is disposed opposite the second side  234 . Two ports  236  are disposed on the first side  232  proximate each end of the lateral member  230  (see  FIG. 2B ). Similarly, four ports  236  are disposed on the second side  124  in a center of the lateral member  230  (see  FIG. 2C ). Ports  236  on the first side  232  are fluidly-coupled to ports  236  on the second side  234  via an internal conduit (e.g., see internal conduit  120  of  FIG. 1B ). However, in general, the ports  236  may be disposed in any number and position such that at least one change in direction occurs for discharged matter entering one side of the lateral member  230  to exit the other. The ports  236  may also have any shape. 
     Lateral member  230  may include a buttress  231  on one or both ends of the structure. Buttress  231  may be coupled with side rails  111  and/or  113  in embodiments. The coupling may include welding, bonding, adhesive, fasteners, or other materials for fixedly coupling the buttress portion of the lateral member  230  to the side rails. Buttress  231  may define one or more apertures  233  through the structure. Apertures  233  may provide access across the lateral members for various mechanical or electrical structures. For example, control cables or wiring may be passed from one battery module to the next to communicatively couple two or more modules together in a variety of ways. Additionally, bus bars may be passed through apertures  233  to electrically couple two or more modules together in a variety of ways. 
     Lateral members  230  may provide both gas mitigation capabilities during cell events as well as structural integrity to the battery pack, and between modules. Lateral members  230  may provide rigidity and support against vibration of the battery pack by supporting cell blocks and modules. The lateral members  230  may additionally operate as heat sinks both during normal operation and during cell events as previously described. While the interior gaps within lateral members  230  may operate to isolate battery modules from one another, the outer walls of lateral members  230  may provide conductive removal of heat to be transferred along lateral members  230  to other structural elements for heat dissipation. 
     It will be appreciated that the internal conduit allows discharged matter to traverse the lateral member  230 . Ports  236  of the lateral members  230  may be positioned to control a distance of flow therein. Ports  236  and the internal conduit of each lateral member  230  are operable to establish a tortuous pathway through a battery pack (e.g., the battery pack  200  of  FIG. 2A ). The tortuous pathway includes one or more changes in direction. Such changes in direction may be any value from 0° to 180° relative to an initial direction. 
     With further reference to  FIG. 2B , in some variations the entrance port for matter from one battery cell can be the exit port for another battery cell. Matter entering and exiting ports  236  would still undergo a series of turns within lateral member  230 . Solid matter can be retained, while vapor matter can continue through the tortuous path. 
     Now referring back to  FIG. 2A , one or more battery cells within the representative cell block  210  may experience a thermal runaway event, yielding an unstable or failing cell block. A corresponding cell block vent of the unstable cell block  210  may open, allowing matter to discharge into a plenum chamber below the battery module. The discharged matter may then follow one or more tortuous pathways that traverse multiple plenum chambers. While traveling along these tortuous pathways, ports  206  and internal conduits  208  of the lateral members  202  force the discharged matter to make at least one change in direction therealong (see arrows). It will be appreciated that cell block vents downstream of the unstable cell block  210  prevent the discharged matter from entering into their corresponding cell blocks. 
     Expansion of the discharged matter continues progressively through adjacent plenum chambers until the discharged matter has insufficient energy to travel further. In some instances, the discharged matter may reach a pack vent  212 , where the discharged matter (or portion thereof) is ejected into an exterior of the battery pack  200 . The pack vent  212  may contain a screen, filter, or other separation member to retain certain components of the discharged matter within the battery pack  200  (e.g., particles). Other possible locations for the screen, filter, or separation member include the ports  206  and internal conduits  208  of the lateral members  202 . 
     A tortuous pathway, by virtue of its at least one change in direction, is capable of separating solid matter from gaseous matter. By forcing matter through changes in direction, the solid matter can be retained within the tortuous pathway. In many instances, this separation results in solid matter being retained within the battery pack  200 . Such retention can inhibit or prevent solid matter from accessing an ambient environment, which is abundant in oxygen. Limiting exposure of the solid matter to ambient oxygen mitigates a risk of ignition outside the battery pack  200 . 
     In some variations, the tortuous pathway is capable of cooling the discharged matter. The tortuous pathway presents an extended path of travel for any matter discharged from a cell block vent. During flow through the tortuous pathway, the discharged matter cools by transferring thermal energy to components of the battery pack  200  (e.g., the lateral members  202 , the plate structure  204 , etc.). Air within the battery pack  200  may also mix with the discharged matter, absorbing thermal energy and cooling the discharged matter. As a result of this cooling, the discharged matter may be rendered incapable of igniting. 
     Each change in direction associated with the tortuous pathway may be any value from 0° to 180° relative to an initial direction. In some variations, the change in direction corresponds to a value equal to or greater than a lower limit. Non-limiting examples of the lower limit include 10°, 30°, 45°, 60°, 90°, 120°, 135°, and 150°. Other lower limits are possible. In some variations, a change in direction corresponds to a value equal to or less than an upper limit. Non-limiting examples of the lower limit include 180°, 150°, 135°, 120°, 90°, 60°, 45°, and 30°. Other upper limits are possible. It will be appreciated that the lower limit and upper limit may be combined in any variation as above to define a range for the change in direction. For example, and without limitation, the change in direction may correspond to a range from 60° to 135° relative to the initial direction. Other ranges are possible. 
     Although  FIG. 2A  depicts the unstable cell block  210  as being in a middle portion of the battery pack, this depiction is not intended as limiting. The unstable cell block  208  may be any position of the battery pack  200 . 
     It will be appreciated that other structural features of a lateral member may be used to define the tortuous pathway.  FIG. 2D  presents a cross-sectional view of a lateral member  238  that includes a throughway  240 , in accordance with an embodiment. The throughway  240  is disposed at a base  242  of the lateral member  238  and allows fluid communication between volumes adjacent a first side  244  and a second side  246 . The lateral member  238  may be analogous to lateral members  106 ,  202 ,  230  described in relation to  FIGS. 1A-1C and 2A-2C . 
     The throughway  240  may include spaces that allow discharged matter to traverse the lateral member  238  from the first side  244  to the second side  246 , or vice versa.  FIG. 2E  presents a perspective view, shown in cross-section, of the throughway  240  of  FIG. 2D , in accordance with an embodiment. The lateral member  238  may include internal voids (e.g., conduits, channels, enclosed cavities, etc.) to reduce its mass. Such voids may be selected by those skilled in the art to maintain a strength or stiffness given a reduction of material in the lateral member  238 . The lateral member  238  may also include one or more spaces  248 , proximate the base  242 , that collectively define the throughway  240 . The spaces  248  extend from the first side  244  of the lateral member  238  to the second side  246 . By virtue of the spaces  248 , volumes adjacent the first side  244  and second side  246  can be fluidly-coupled. Spaces  248  are depicted as arrays of spaces  248 , each array having spaces  248  aligned perpendicular to the first and second sides  244 ,  246  of the lateral member  238 . However, this depiction is not intended as limiting. Other arrangements are possible for the spaces  248 . 
     The spaces  248  are separated by pillar structures  250  formed by material of the lateral member  238 . The pillar structures  250  may decrease a velocity of matter traversing the throughway  240 . For example, and without limitation, the pillar structures  250  may be spaced such that the matter traversing the throughway  240  impinges upon the pillar structures  250  or drags along surfaces thereof. The pillar structures  250  may also induce turbulence in matter traversing the throughway  240 . Without wishing to be limited to any mechanism or mode of action, such turbulence may result from impingement upon the pillar structures  250  or drag along surfaces of the pillar structures  250 . 
     Spaces  248  may be spaced and oriented to order the pillar structures  250  into a lattice (or groups of such lattices). Such ordering may influence a degree of turbulence experienced by matter traversing the throughway  240 . The ordering may also allow the pillar structures  250  to increase an interaction of matter traversing the throughway  240  with surfaces of the pillar structures  250 . 
     In some variations, such as shown in  FIG. 2E , adjacent rows of pillar structures are aligned such that flow paths therethrough are unimpeded. In other embodiments, adjacent rows of pillar structures  250  are offset relative to each other to create flow paths having impediments thereon. In some embodiments, the lateral members  238  have slots formed into the base  242 . In these embodiments, each slot may extend from a bottom side  252  of the lateral member  238  to a single space. 
     During operation, the pillar structures  250  allow the lateral member  238  to establish a tortuous pathway (or portion thereof) for matter discharged from cell blocks.  FIG. 2F  presents a perspective view of a cell block  254  disposed between a first lateral member  256  and a second lateral member  258 , in accordance with an embodiment. The cell block  254  is part of a battery module  260 , which in turn, serves as part of a battery pack. The first and second lateral members  256 ,  258  can be the lateral member  238  described in  FIGS. 2D-2E . The cell block  254  is suspended by the first and second lateral members  256 ,  258  above a plate structure  262 . This suspension forms a gap  264  between the cell block  254  and the plate structure  262  that is common to all cell blocks in the battery module  260 . The gap  264  thereby helps to define a plenum chamber  266  below the battery module  260 . 
     Cell block  254  may discharge matter from one or more failing batteries into the plenum chamber  266 , as shown by arrows  268 . The plate structure  262  redirects this discharged matter towards respective throughways  270 ,  272  of the first and second lateral members  256 ,  258 . In some instances, such redirection is assisted by a cell block vent of the cell block. 
     While traversing the throughways  270 ,  272 , the discharged matter encounters pillar structures  274  that decrease a velocity of the discharged matter. The pillar structures  274  may also induce turbulent flow within the discharged matter that causes changes in direction. As a result, the pillar structures  274  may increase a chance to trap debris from the discharged matter, such as hot particles, within the throughways  270 ,  272 . The inducement of turbulent flow may additionally increase contact of the discharged matter with surfaces of the pillar structures. This increased contact may improve transfer of heat from the discharged matter to the lateral members  256 ,  258 , thereby lowering a temperature of the discharged matter. 
     Now referring to  FIG. 3A , a schematic diagram is presented of a testing apparatus  300  that includes a cell block  302  and a plenum chamber  304 , according to an illustrative embodiment. A plurality of thermocouples  306 ,  308 ,  310 , and  312  is disposed in the cell block  302  and along a discharge path within the plenum chamber  304 . The testing apparatus  300  is configured to measure temperatures that occur at different locations relative to cell block  302 . 
       FIG. 3B  presents a graph of temperatures  316 ,  318 ,  320 , and  322  measured by the testing apparatus  300  during a representative thermal runaway event. The graph shows a dependence of the temperatures  316 ,  318 ,  320 , and  322  with time. The temperatures of  FIG. 3B  include a first model cell block temperature  316 , which is measured by a first thermocouple  306 ; a second model cell block temperature  318 , which is measured by a second thermocouple  308 ; an exterior temperature  320  in the model plenum chamber  304  and adjacent a neighboring component  324 , measured by a third thermocouple  310 ; and a neighboring temperature  320  inside the neighboring component  324 . The temperatures in  FIG. 3B  further include a temperature at the entrance to neighboring component  326  of the neighboring component  324 , measured by a fourth thermocouple  312 . Entrance to neighboring component  326  models the location of a cell block vent  162  in  FIG. 1C . Further, it will be appreciated that the neighboring component  324  in  FIG. 3A  models the location of second cell block  152  in  FIG. 1C . Although  FIG. 3A  depicts thermal insulation around the cell block  302 , this depiction is for purposes of illustration only. 
     Returning to  FIG. 3A , temperatures  314  and  316  model internal temperatures of the cell block  302  that may occur as the result of a thermal runaway event. The exterior temperature  318 , which is measured adjacent the neighboring component  324 , increases rapidly after the thermal runaway event, but also decreases quickly (i.e., within minutes) to asymptotically approach a temperature of about 100° C. This behavior is different than first and second cell block temperatures  314 ,  316 , which remain relatively high (i.e., above 500° C.). Neighboring temperature  320 , however, increases only a small amount (i.e., stays below about 50° C.). It will be appreciated that the behavior of neighboring temperature  320  suggests a limited transfer of thermal energy into the neighboring component  324 . Thus, the discharged matter has cooled sufficiently during expansion within the plenum chamber  304  that the neighboring component  324  does not reach temperatures capable of inducing a subsequent thermal runaway event (e.g., a thermal runaway event in a neighboring cell block). Moreover, the cell block vent  326  of the neighboring component  324 , by virtue of its outward-flow configuration, has prevented the discharged matter from entering the neighboring component  324 . In doing so, the cell block vent  326  has isolated the discharged matter to the plenum chamber  304 , restricting it to cool therein and flow elsewhere. 
     Although  FIGS. 1A-3B  depict battery cells of a battery pack in the context of cell blocks and cell block vents, other configurations of battery cells are possible. However, as described below, the battery cells may be fluidly-coupled to a pack vent of the battery pack via respective cell vents. 
     Representative examples of such alternative embodiments are described in relation to  FIGS. 4A-4D and 5A-5C . Moreover, in certain embodiments, the battery pack may have a plurality of pack vents. 
       FIG. 4A  illustrates portions of a battery pack  400 , according to an illustrative embodiment. The components of the battery pack  400  are arranged to control discharges of matter during thermal runaway. The battery pack  400  includes a battery pack structure  404 . The battery pack  400  also includes a plurality of battery cells  402  disposed on the battery pack structure  404 . Battery cells  402  each have a cell vent  406  operable to discharge matter during the thermal runaway event. The cell vent  406  is shaped and positioned to permit discharge of matter from within the battery cell  402  towards an exterior of the battery cell  402 . Non-limiting examples of discharged matter include vapors, gases, char, electrolyte fluid, and solid matter (including solid battery materials). Other types of discharged matter are possible. The discharged matter may be in a combusted state, an uncombusted state, or some combination thereof. 
     The cell vent  406  may be incorporated in whole or in part into an enclosure of each battery cell. In  FIG. 4A , the cell vent  406  is depicted as internal to its corresponding battery cell  402 . However, this depiction is not intended as limiting. The cell vent  406  may have a portion external to the battery cell  402 . In some embodiments, the cell vent  406  includes a passive occlusion (e.g., a frangible seal). In other embodiments, the cell vent  406  includes an active occlusion (e.g., a microprocessor-controlled valve). 
     The battery pack  400  also includes a pack vent  408  disposed on the battery pack structure  404  and fluidly-coupled to at least one of the cell vents  406 . The pack vent  408  is shaped and positioned to permit discharged matter to pass from the at least one cell vent  406  (or multiples thereof) to an exterior  412  of the battery pack  400 . In some embodiments, the pack vent  408  includes an orifice. The orifice may be directly exposed to the exterior  412  of the battery pack  400 . In some embodiments, the pack vent  408  includes an occluding member for blocking or at least impeding a flow pathway through the pack vent  408  (e.g., a frangible seal, a plug, a valve, or similar component). The occluding member may be passive (e.g., a plug) or active (e.g., microprocessor-controlled). In further embodiments, the occluding member comprises thermal insulation. 
     The pack vent  408  may be incorporated in whole or in part within the wall  410  of the battery pack structure  404 .  FIG. 4A  depicts a variation where the pack vent  408  has a portion protruding into the exterior  412  of the battery pack  400 . However, this depiction is not intended as limiting. Other arrangements for the pack vent  408  are possible. Moreover, any number of pack vents  408  may be disposed within the wall  410 .  FIG. 4A  illustrates a non-limiting variation where two pack vents  408  are disposed within the wall  410 . 
     Fluid coupling between the pack vent  408  and the cell vent  406  (or multiples thereof) may involve structures and seals that operate at elevated temperatures and pressures (i.e., T&gt;300° C. and P&gt;500 kPa). Such structures and seals are configured to maintain mechanical integrity under vibrational loads and shocks from impact loads. The structures and seals may also be formed of materials chemically-resistant to discharged matter from the battery cell  402  (e.g., electrolyte vapors, particles of cathode active material, etc.). Embodiments of the structures and seals are described later in relation to  FIGS. 4A-4D . 
     In some embodiments, such as that shown in  FIG. 4A , the cell vent  406  is disposed on a side  414  different than that of a battery terminal  416  (e.g., an adjacent side, an opposite side, or a bottom side). In some embodiments, the battery pack  400  includes a plurality of pack vents  408  disposed within the wall  410  of the battery pack structure  404 . 
     In some embodiments, the cell vents  406  include a cell vent having a flow guide configured to alter a direction of discharged matter passing through the flow guide. In some embodiments, the pack vent  408  includes a flow guide configured to alter a direction of discharged matter passing through the pack vent  408 . Non-limiting examples of the flow guide include a nozzle and a louver. 
     In some embodiments, the occluding member is configured to allow discharged matter to flow from the cell vent  406  (or multiples thereof) to the exterior  412  of the battery pack structure  404 . However, in these embodiments, the occluding member is also configured to block or at least impede discharged matter from flowing from the exterior  412  of the battery pack structure  404  towards the cell vent  406  (or multiples thereof). This configuration may prevent discharged matter (i.e., from an unstable battery cell) from breaching one or more pack vents  408  to interact with neighboring battery cells. The configuration may also be beneficial in avoiding thermal contagion within a battery pack  400 . 
     In some embodiments, the cell vents  406  include a cell vent having a back-flow prevention mechanism. The back-flow prevention mechanism is configured to block or at least impede discharged matter from entering a battery cell through its cell vent and permit discharge of matter from within the battery cell towards the exterior of the battery cell during the thermal runaway event. 
     In some embodiments, the cell vents  406  comprise a cell vent having an occluding member for blocking or at least impeding a flow pathway through the cell vent. The occluding member includes thermal insulation configured to melt at a temperature experienced during the thermal runaway event. 
     In some embodiments, the pack vent  408  includes a back-flow prevention mechanism. The back-flow prevention mechanism is configured to block or at least impede matter from entering the battery pack structure  404  through the pack vent  408  and permit discharge of matter from the plurality of battery cells  402  towards the exterior of the battery pack  412  during the thermal runaway event. 
     In some embodiments, the pack vent  408  includes an occluding member for blocking or at least impeding a flow pathway through the pack vent  408 . The occluding member includes thermal insulation configured to melt at a temperature experienced during the thermal runaway event. 
     During operation of the battery pack  400 , the plurality of battery cells  402  receive electrical energy from a source to charge and supply electrical energy to a sink to discharge. However, during operation one or more battery cells  402  may become less stable, e.g., electrochemical reactions in the one or more battery cells  402  may accelerate. As a result, the one or more battery cells  402  may generate heat at rates outside of a tolerance of the one or more battery cells  402 . If not dissipated, this heat can catalyze thermal runaway, quickly elevating internal temperatures and pressures within the one or more battery cells  402 . 
     It will be appreciated that the battery pack  400  is configured to allow less stable battery cells  402  to discharge hot, pressurized matter into a controlled volume, which is bounded by the cell vent  406 , the pack vent  408 , and fluid-coupling therebetween. The controlled volume is operable to prevent discharged matter from interacting with neighboring battery cells  402  (e.g., interacting thermally, mechanically, chemically, etc.). 
     During thermal runaway, the cell vent  406  opens to allow matter to discharge from a corresponding battery cell  402 . The cell vent  406  may open in response to a threshold being exceeded, such as a predetermined temperature or a predetermined pressure. The discharged matter, by virtue of fluid-coupling between the cell vent  406  and the pack vent  408 , enters the pack vent  408  to traverse the wall  410  of the housing  404  (i.e., to reach the exterior  412 ). The optional flow guide, if present, may guide the direction of discharged matter into the exterior  412 . 
     In some embodiments, such as that depicted in  FIG. 4A , the battery pack  400  includes the plurality of pack vents  408  disposed with the wall  410  of the housing  404  and a conduit  418  fluidly-coupling a pack vent  408  to a cell vent  406 . In these embodiments, discharges of matter from a single battery cell are separated from other battery cells. The conduit  418  may include a first end  420  sealed to a pack vent  408  and a second end  422  sealed to a cell vent  406 . The conduit  418  and seals involve materials resistant to elevated temperatures and pressures (i.e., T&gt;300° C. and P&gt;500 kPa). In some instances, the seals can be a gasket, a sealing compound, a polymeric O-ring, a mechanical interference fit, or combinations thereof. In some instances, the conduit  418  includes thermal insulation (e.g., alumina insulation tape, fibrous silica felt, a polyurethane coating, etc.). 
     In some instances, the conduit  418  may be formed of a metal material (e.g., be a metal tube). Non-limiting examples of metal for the conduit  418  include aluminum and aluminum-based alloys; iron and iron-based alloys (e.g., steel and stainless steel); nickel and nickel-based alloys; titanium and titanium-based alloys; and zirconium and zirconium-based alloys. Other metals are possible. In some instances, the metal has a melting point greater than 1000° C. In some instances, the metal has a melting point greater than 1300° C. In some instances, the metal has a melting point greater than 1600° C. In some instances, the metal has a thermal conductivity lower than 160 W/m·K. In some instances, the metal has a thermal conductivity lower than 120 W/m·K. In some instances, the metal has a thermal conductivity lower than 80 W/m·K. 
     In other embodiments, the conduit  418  may be formed of a ceramic material, such as alumina, fused quartz, zirconia, mullite, and so forth. In these instances, the conduit  418  may also include a reinforcing structure selected from the group consisting of an inner pipe, an outer pipe, a coating, or combinations thereof. The inner pipe and the outer pipe may be formed of metal material, or alternatively, a plastic material (e.g., a polyetherketone material, a polyphenylene styrene material, a polyurethane material, etc.). Non-limiting examples of the coating include sprayed-on coatings, dip coatings, painted coatings, and laminates (e.g., laminated layers and fibers). Other coating types are possible. In some instances, the coating includes ceramic filler particles (e.g., filler particles of alumina, zirconia, silica, silicon nitride, mullite, etc.). In some instances, the coating is operable to seal the conduit  418  to the pack vent  408  and the cell vent  406 . 
     Although  FIG. 4A  depicts the battery pack  400  with a one-to-one coupling of pack vents  408  to the cell vents  406 , this depiction is for purposes of illustration only. Other types of couplings are possible. 
       FIG. 4B  illustrates portions of a battery pack  400 , in accordance with an illustrative embodiment. In these embodiments, a manifold  420  fluidly-couples one pack vent  408  to two or more cell vents  406 . The manifold  420  may include an outtake port  422  sealed to a pack vent  408  and a plurality of intake ports  424 , each sealed to one cell vent  406 . The manifold  420  and seals involve materials resistant to elevated temperatures and pressures (i.e., T&gt;300° C. and P&gt;500 kPa). In these embodiments, discharges of matter from one or more battery cells  402  within a group are separated from other battery cells. In  FIG. 4B , the manifold  420  is depicted as fluidly-coupling one pack vent  408  to two cell vents  406 . However, this depiction is not intended as limiting. The manifold  420  may fluidly-couple any plurality of cell vents  406  to the pack vent  408 . In some instances, the seals include a gasket, a sealing compound, a polymeric O-ring, a mechanical interference fit, or combinations thereof. In some instances, the manifold  420  includes thermal insulation (e.g., alumina insulation tape, fibrous silica felt, a polyurethane coating, etc.). 
     In some instances, the manifold  420  may be formed of a metal material (e.g., be a metal tube). Non-limiting examples of metal for the manifold  420  include aluminum and aluminum-based alloys; iron and iron-based alloys (e.g., steel and stainless steel); nickel and nickel-based alloys; titanium and titanium-based alloys; and zirconium and zirconium-based alloys. Other metals are possible. In some instances, the metal has a melting point greater than 1000° C. In some instances, the metal has a melting point greater than 1300° C. In some instances, the metal has a melting point greater than 1600° C. In some instances, the metal has a thermal conductivity lower than 160 W/m·K. In some instances, the metal has a thermal conductivity lower than 120 W/m·K. In some instances, the metal has a thermal conductivity lower than 80 W/m·K. 
     The manifold  420  may also be formed of a ceramic material, such as alumina, fused quartz, zirconia, mullite, and so forth. In these instances, the manifold  420  may include at least one reinforcing structure selected from the group consisting of an inner pipe, an outer pipe, a coating, or combinations thereof. The inner pipe and the outer pipe may be formed of a metal material, or alternatively, a plastic material (e.g., a polyetherketone material, a polyphenylene styrene material, a polyurethane material, etc.). Non-limiting examples of the coating include sprayed-on coatings, dip coatings, painted coatings, and laminates (e.g., laminated layers and fibers). Other coating types are possible. In some instances, the coating includes ceramic filler particles (e.g., filler particles of alumina, zirconia, silica, silicon nitride, mullite, etc.). In some instances, the coating is operable to seal the manifold  420  to a pack vent  408  and two or more corresponding cell vents  406 . 
     Although  FIGS. 4A &amp; 4B  depict the cell vents  406  as being displaced away from the pack vent  408 , this depiction is not intended as limiting. The cell vents  406  may be disposed adjacent the pack vent  408 . 
       FIG. 4C  illustrates a portion of a battery pack  400  in some embodiments. In these embodiments, the cell vents  406  are coupled directly to pack vents  408  via a seal  426 . The battery pack  400  includes the plurality of pack vents  408  disposed within the wall  410  of the battery pack structure  404 . Each pack vent  408  is fluidly-coupled to a cell vent  406  and has an interface  428  therewith. The seal  426  is disposed along the interface  428 . The seal  426  may include a gasket, a sealing compound, a polymeric O-ring, a mechanical interference fit, or combinations thereof. In these embodiments, discharges of matter from a single battery cell are separated from other battery cells. In some instances, each of the plurality of pack vents  408  is configured such that one cell vent  406  is nested therein. In these instances, such nesting may improve a delivery of discharged matter into each of the plurality of pack vents  408 . 
     Although  FIGS. 4A-4C  illustrate cell vents  406  and pack vents  408  as being distinct structures, in some embodiments, cell vents  406  and pack vents  408  may be integrated into a unified structural element. Such integration may involve any number and combination of cell vents  406  and pack vents  408 . 
       FIG. 4D  illustrates a portion of a battery pack  400  in some embodiments. In these embodiments, the cell vents  406  and the pack vents  408  serve as portions of an integrated vent  430 . The battery pack  400  includes the plurality of pack vents  408  disposed within the wall  410  of the battery pack structure  404 . The integrated vent  430  has a first portion  432  and a second portion  434 . The first portion  432  includes a cell vent  406  and the second portion  434  includes a pack vent  408 . In these embodiments, discharges of matter from a single battery cell are separated from other battery cells. 
     In some instances, the integrated vent  430  may be formed of a metal material (e.g., be a metal tube). Non-limiting examples of metal for the conduit  418  include aluminum and aluminum-based alloys; iron and iron-based alloys (e.g., steel and stainless steel); nickel and nickel-based alloys; titanium and titanium-based alloys; and zirconium and zirconium-based alloys. Other metals are possible. In some instances, the metal has a melting point greater than 1000° C. In some instances, the metal has a melting point greater than 1300° C. In some instances, the metal has a melting point greater than 1600° C. In some instances, the metal has a thermal conductivity lower than 160 W/m·K. In some instances, the metal has a thermal conductivity lower than 120 W/m·K. In some instances, the metal has a thermal conductivity lower than 80 W/m·K. 
     The integrated vent  430  may also be formed of a ceramic material, such as alumina, fused quartz, zirconia, mullite, and so forth. In these instances, the integrated vent  430  may include a reinforcing structure selected from the group consisting of an inner pipe, an outer pipe, a coating, or combinations thereof. The inner pipe and the outer pipe may be formed of metal material, or alternatively, a plastic material (e.g., a polyetherketone material, a polyphenylene styrene material, a polyurethane material, etc.). Non-limiting examples of the coating include sprayed-on coatings, dip coatings, painted coatings, and laminates (e.g., laminated layers and fibers). Other coating types are possible. In some instances, the coating includes ceramic filler particles (e.g., filler particles of alumina, zirconia, silica, silicon nitride, mullite, etc.). In some instances, the coating is operable to seal the integrated vent  430  to the wall  410  and one battery cell  402 . 
     Although  FIGS. 4A-4D  illustrate representative portions of the battery pack  400 , it will be appreciated that, in general, such portions can be incorporated in any number and combination within the battery pack  400 . Moreover, in certain embodiments, the battery pack  400  may further include a plenum chamber fluidly-coupled to one or more cell vents of the battery cells. As described below, the plenum chamber may have a plenum vent that functions analogous to a pack vent for the battery pack  400 . The plenum chamber may also have one or more flow guides disposed therein to direct matter discharged from a battery cell during a thermal runaway event. 
     Now referring to  FIG. 5A , a schematic cross-section diagram is presented of a system  500  for directing discharged matter from battery cells, in accordance with an illustrative embodiment. For clarity, only a portion of the system  500  is shown. The system  500  includes a battery pack structure  504 . The system  500  also includes a plurality of battery cells  502  disposed on the battery pack structure  504 . Each battery cell  502  has a cell vent  506  that is shaped and positioned to permit discharges of matter from within the battery cell  502  towards an exterior of the battery cell  502  during a thermal runaway event. The battery cell  502  and the cell vent  506  may be analogous to that described in relation to  FIGS. 5A-5D . In some embodiments, the cell vent  506  is disposed on a side  508  different than that of a battery terminal  510 . 
     The system  500  additionally includes a plate structure  512  coupled with the battery pack structure  504  to form a plenum chamber. The plate structure  512  includes at least one flow guide  522  and at least one occluding member (see also  FIGS. 5B &amp; 5C ). The at least one flow guide  522  and the at least one occluding member operate, during the thermal runaway event, to facilitate flow of vapor released from the cell vents  506  towards a plenum vent  520  to an external ambient environment and impede flow of solid battery material discharged from the cell vents  506  towards the plenum vent  520 . 
     In some embodiments, the plate structure  512  has a first plate  514  disposed opposite a second plate  516 . The first plate  514  has a plurality of openings  518  disposed therein. The plurality of openings  518  may have any number, shape, and arrangement within the first plate  514 . The plurality of openings  518  is fluidly-coupled to cell vents  506  of the plurality of battery cells  502 . Such fluid coupling may involve one or more seals selected from the group consisting of a gasket, a sealing compound, a polymeric O-ring, a mechanical interference fit, or combinations thereof. The seals may involve materials resistant to elevated temperatures and pressures (i.e., T&gt;300° C. and P&gt;500 kPa). In some embodiments, such as that shown in  FIG. 5A , each of the plurality of openings  518  is fluidly-coupled to one cell vent  506 . 
     The plenum vent  520  is disposed on the plate structure  512  and fluidly-coupled to the plurality of openings  518 . The plenum vent  520  may include a nozzle, a louver, or both, to direct discharged matter exiting the plate structure  512 . In some instances, such as that shown in  FIG. 5A , the plenum vent  520  is disposed in a side of the plate structure  512 . In other instances, the plenum vent  520  is disposed in the second plate  516 . Although  FIG. 5A  depicts only one plenum vent  520 , this depiction is not intended as limiting. Multiple plenum vents  520  are possible, including any shape and arrangement of plenum vents  520  in the plate structure  512 . 
     The at least one flow guide  522  may be disposed between the first plate  514  and the second plate  516  (e.g., see also  FIGS. 5B &amp; 5C ). The flow guide  522  may be operable to establish a tortuous pathway for matter discharged into the plate structure  512 . The tortuous pathway may allow hot particles and gasses to be separated via inertia while flowing through the plate structure  512 . Such separation may prevent ignition of the discharged matter outside the plate structure  512  (e.g., if combustible constituents are present in the discharged matter). In some embodiments, the at least one flow guide  522  is arranged to direct discharged matter along a flow path having a turn of at least 90°. The flow path may extend from one or more openings  518  to the plenum vent  520 . In some embodiments, the plate structure  512  includes a screen disposed therein. In these embodiments, the screen may capture hot particles from the discharged matter, thereby retaining such particles within the plate structure  512 . 
       FIGS. 5B and 5C  present top views of embodiments of the plate structure  512  illustrated in  FIG. 5A . In  FIG. 5B , angled baffles  524  extend from side walls of the plate structure  512  to supplement an arcuate wall  526  disposed adjacent the plenum vent  520 . The angled baffles  524  and the arcuate wall  526  represent flow guides  522  and help to define a flow path  528  having a turn of at least 90°. For clarity, only a portion of the flow path  528  is shown in  FIG. 5B . In  FIG. 5C , a rectangular wall  530  is disposed within the plate structure  512  to enclose flow paths emanating from the plurality of openings  518 . The rectangular wall  530  merges into the plate structure  512  via tapers  532  having vents  534 . Flow through the vents  534  is impeded by baffles  536  disposed proximate the vents  534 . The rectangular wall  530 , tapers  532 , and baffles  536  represent flow guides  522  and help to define a flow path  538  having multiple turns of at least 90°. For clarity, only a portion of the flow path  538  is shown in  FIG. 5C . 
     During operation of the system  500 , one or more battery cells  502  may experience thermal runaway, causing corresponding cell vents  506  to open and discharge matter through respective openings  518 . Matter so-discharged enters the plate structure  512  (i.e., the plenum chamber) and flows along a flow path bounded by the at least one flow guide  522 . The flow path extends from one or more openings  518  to the plenum vent  520 . In some instances, the flow path is tortuous and may optionally include the screen. Tortuous flow may separate particles from gasses in the discharged matter via inertial separation. The screen, if present, may assist in separating such particles mechanically. Separation of the particles may reduce a risk of ignition outside of the plate structure  512 . 
     Because discharges from less stable battery cells  502  may occur at elevated temperatures and pressures (i.e., T&gt;300° C. and P&gt;500 kPa), interaction of discharged matter with the plurality of battery cells  502  is undesirable (i.e., interaction thermally, mechanically, chemically, etc.). The plate structure  512  represents a segregated volume capable of receiving such discharged matter and keeping this matter away from the plurality of battery cells  502 . Moreover, the plate structure  512  may allow discharged matter to cool and depressurize, thereby reducing a tendency of such matter to ignite upon exiting the plate structure  512 . 
     Turning to  FIG. 6  is illustrated an exploded perspective view of a battery module  600  according to embodiments of the present technology. Battery module  600  may be one of a number of battery modules that may be included within a battery pack, as previously described. Battery module  600  is illustrated in an inverted position from previous figures for ease of description. The battery module  600  may include a number of battery cell blocks  602 , which each include one or more battery cells  610 . As illustrated, each cell block  602  includes four individual battery cells  610 , although it is to be understood that embodiments may include any number of battery cells per battery cell block, such as at least about two cells, at least about four cells, at least about six cells, or more. Additionally, the battery module  600  may include any number of battery cell blocks within the module based on length of the module, which may be based on one of several lateral dimensions of a battery pack. 
     Battery cells  610  may be similar to one another or may be different across the cell blocks and module. In embodiments, each battery cell  610  may be a similar battery cell as each other battery cell. Battery cells  610  may be or include prismatic cells, pouch cells, or any number of other battery cell designs. As previously noted,  FIG. 6A  may illustrate an inverted view of battery module  600 , and may illustrate a bottom or base surface of battery cells  610 . As shown, a surface of each battery cell  610 , which may include a bottom surface, may include terminals  612  as well as a cell vent  614  in embodiments. 
     Each cell block  602  may include a number of battery cells coupled with one another, such as with adhesive, to limit spacing between battery cells. Thermal insulation  616  may be positioned on sides surrounding each cell block  602 . Thermal insulation  616  may provide multiple benefits within a battery module. For example, thermal insulation about the sides of each cell block may limit thermal conductivity from one cell block to another. Additionally, thermal insulation  616  may be or include a compressive material to provide accommodation space within each cell block. 
     As battery cells are cycled during their life, the cells may swell over time. When cells are rigidly compressed or contained within a particular structure, the cells may have reduced cycle life. The present technology, however, may include thermal insulation configured to provide an amount of deflection or compression to accommodate swelling of battery cells over time. The thermal insulation  616  may be configured to fully occupy space within each cell block to limit any gaps within the block. However, the thermal insulation material may be configured to accommodate compression of up to or about 50% or more of its thickness to accommodate battery swelling over time. Unlike conventional technology that may not provide such accommodation, the present technology may produce longer battery life cycles based on the incorporated accommodation of battery swelling within each cell block. 
     Opposite ends of each cell block  602  in an axial direction of battery module  600  may include a bulkhead  620 . Bulkhead  620  may be a rigid member separating each cell block  602  from an adjacent cell block. Bulkhead  620  may be aluminum, steel, ceramic, plastic, or any number of other materials to separate cell blocks or contain cell blocks. Bulkheads  620  may include a flange  622 , which may facilitate coupling of the bulkhead  620  with a sleeve or shroud  625 . Shroud  625  may extend over a number of sides of each cell block  602 . For example, shroud  625  may extend about sides and a bottom of each cell block in embodiments. Shroud  625  may define or include cell block vents  627 , which may be any of the cell block vents previously described. Shroud  625  may include a cell block vent  627  for each cell block included in module  600 , or may include more or fewer vents as there are cell blocks. 
     Shroud  625  may be welded, bonded, glued, fastened, or otherwise coupled with bulkheads  620  on sides of the module. Flanges  622  of bulkheads  620  may extend as an end joint on the bulkheads  620 . The flange may extend back towards the bulkheads  620  in a 180 degree rounded turn, which may provide protection for a weld. During certain welding operations coupling the shroud  625  with the flanges  622  of each bulkhead  620 , sputtering may occur through the backside of the flange. By having the flange double back on itself, any sputtering may be contained within a loop formed by the flange. This may limit or prevent any sputtered material from contacting any cells of the cell block. Bulkheads  620  and shroud  625  may provide structural rigidity to the module  600 , which may limit vibration effects on the cell blocks  602 . 
     Bulkheads  620  may also define a recess  624  along a surface of the bulkhead  620  in line with terminals  612  of the battery cells  610 . Cell blocks  602  may be joined together with bus bars  630 ,  632  in embodiments. Bus bars  630  may be intra-cell block bus bars that electrically couple individual cells of each cell block  602 . Bus bars  632  may be inter-cell block bus bars that couple adjacent cell blocks of the modules. Recess  624 , which may be a notch defined in the bulkhead  620 , may provide access for bus bars  632  to extend from one cell block to another. 
     Bus bars  630 ,  632  may be seated in a tray positioned between cell blocks  602  and shroud  625 . Tray  635  may include features to seat the bus bars to ensure proper spacing between cell blocks, and also to electrically insulate the various structures. Bus bar tray  635  may define one or more channels or apertures through the bus bar tray to allow egress of material from cell vents within each battery cell  610 . For example, for battery cells including a centrally located cell vent, bus bar tray  635  may include a central channel to provide access to the cell block vents  627  from the cell vents  614 . 
     A thermal interface material  640  may be coupled or placed along a surface of each cell block opposite a surface facing cell block vents  627  of shroud  625 . The thermal interface material  640  may be configured to conduct or transfer heat generated from battery cells  610  through a top of the battery module  600 . Thermal interface material may be included in individual sheets that may be placed on a surface of each cell block and may be sized relative to a cell block size, or a length of thermal interface material may be positioned along an axial length of battery module  600 . 
     Battery module  600  may also include a top cover  645 , which may provide a lid to the battery module  600 . Shroud  625  may include a lip or flange  626  on either or both sides of the structure to provide a coupling location for top cover  645 . Additionally, flange  626  may be used to seat battery module  600  on lateral members such as previously described, when battery module  600  is inverted and positioned within a battery pack. By seating on a top portion of lateral members, a bottom of shroud  625  and a bottom plate, such as plate structure  114  previously described, may define a volume for plenum chambers between adjacent lateral members. 
     Top cover  645  and shroud  625  may be a rigid material in embodiments, and may be aluminum, steel, or some other structural material configured to house and contain cell blocks of a battery module. The top cover and shroud may be configured to control an internal volume of the battery module to limit or prevent egress from the battery module except through cell block vents  627 , which may lead into plenum channels previously described. By providing a rigid structure to control material egress, mitigation of effluent materials from a cell failure may be better controlled to allow temperature reduction and/or material treatment along a tortuous path through the plenum structure as previously described. 
       FIG. 7A  shows a close-up view of tray  635  according to some embodiments of the present technology. As noted above, tray  635  may include the bus bars coupling each cell within a cell block, such as intra cell block bus bar  630 , as well as the bus bars coupling each cell block to an adjacent cell block, such as inter cell block bus bar  632 . Tray  635  may form a distance or thickness within each cell block between the cells of the cell block and the shroud that may include the cell block vents  627 . This distance may produce a small interior plenum of each cell block in which effluents may flow prior to being delivered into a battery pack plenum through the cell block vents. Because inter cell block bus bars  632  are positioned to extend between adjacent cell blocks, bulkhead  622  may include a notch to accommodate the bus bars. By forming this notch, a pathway may be formed between adjacent cell blocks. Additionally, a channel  720  may be formed in the tray  635 , and may provide a channel for wiring to extend across the module between cell blocks. 
     These pathways, if left unblocked, may provide access between cell blocks for effluents of a failed cell or cell block to contact cells of the adjacent cell block. If allowed to occur, the effluents may cause damage or failure to the adjacent cells, which may propagate a failure from cell block to cell block, and which may proceed throughout the battery pack. Accordingly, some embodiments may utilize a bus bar seal  710  to block access for effluent gases and particles generated in one cell block from passing into neighboring cell blocks. Bus bar seal  710  may be or include a single piece of material or multiple pieces of material that may provide both protection against effluent materials passing between neighboring cell blocks, as well as insulation between components that may be at different electrical potential. 
       FIG. 7B  illustrates an additional view of bus bar seal  710  when positioned about bulkhead  622  and bus bar  632 . Bus bar seal  710  may extend about bus bar  632  to form a seal capable of limiting or preventing gas or other effluent material from passing along bus bar  632  from one cell into an adjacent cell. The seal about bus bar  632  may be formed upon coupling of the bus bar seal  710  to bus bar  632 , or may be formed during an event, such as failure of a cell or cell block. Bus bar seal  710  may also define a slot or space to extend across bulkhead  622 , which may limit any gaps between the bus bar seal  710  and bulkhead  622 . Bus bar seal  710  may extend slightly above (or below when inverted) a height of bulkhead  622 . This may allow shroud  625  to compress bus bar seal  710  along a length of the material to further ensure gaps are limited or removed between the bus bar seal  710 , the bus bar  632 , and/or the bulkhead  622 . 
       FIG. 7C  illustrates a schematic view of an exemplary bus bar seal  710  according to embodiments of the present technology. Bus bar seal  710  may include a defined shape, such as illustrated, but other materials may be utilized for bus bar seal  710 , which may be more amorphous during coupling operations. When including a defined shape, bus bar seal  710  may be characterized by a shape configured to reduce, limit, or prevent gaps about a bus bar to which bus bar seal  710  may be coupled about, as well as reduce, limit, or prevent gaps with a component with which bus bar seal  710  may be coupled, such as bulkhead  622 . For example, bus bar seal  710  may include a first surface  712  characterized by a planar or substantially planar profile, which may provide contact with a shroud along an entire length of the bus bar seal  710  at first surface  712 . Bus bar seal  710  may also define a slot  714 , which may extend about a bulkhead or other component separating adjacent cell blocks. 
     In some embodiments, bus bar seal  710  may be one or more pieces of material having a defined shape, such as illustrated. Bus bar seal  710  may be one piece, two pieces, three pieces, four pieces, or more, although it is to be understood that the more pieces included in the design may provide more locations for seepage of effluent materials at the junctures of the pieces. A one-piece design of bus bar seal  710  may include an annular component, or a component defining a rectangular, ovular, or other gap within which bus bar  632  may be disposed. A one-piece design of bus bar seal  710  may also include a clam-shell configuration or configuration including a joint connecting two elongate elements which may be compressed about a bus bar. An exemplary two-piece design is shown in  FIG. 7D  with bus bar seal  715 . Bus bar seal  715  may include a first component  716 , which may include a surface  717  that may contact a shroud or other housing component of a battery module. Bus bar seal  715  may also include a second component  718 , which may define a slot  719  within which a bulkhead may be seated. Utilizing a multi-piece bus bar seal may produce wider or thicker bus bar seals as the creepage and clearance requirements may become more difficult to maintain. Accordingly, a single-piece design may afford more compact components with reduced creepage and clearance requirements. 
     The materials used for a bus bar seal may depend on the particular design in some embodiments. For example, a one-piece bus bar seal defining an ovular or rectangular gap for a bus bar may be characterized by an elasticity allowing the bus bar seal to be stretched over terminal connections of the bus bar and positioned proximate an interior position of the bus bar, such as a central location between terminals of the bus bar. Accordingly, exemplary bus bar seals may be characterized by up to or greater than about a 500% stretch-to-failure property, although in embodiments the bus bar seal may be characterized by a stretch-to-failure amount of less than or about 450%, less than or about 400%, less than or about 350%, less than or about 300%, less than or about 250%, less than or about 200%, less than or about 150%, or less depending on the amount of stretch required to position the bus bar seal about a central or interior portion of a bus bar. This may also be based on a shape of the bus bar itself. For example, a rectangular bus bar may allow a bus bar seal to be slid into place, which may utilize a minimal amount of stretch. In other embodiments in which portions of the bus bar may be characterized by a length greater than the length of a position at which the bus bar seal may be coupled, the bus bar seal may be characterized by a greater amount of flexibility. 
     The bus bar seal may be overmolded on a bus bar, which may allow use of flowable or setting materials. When the bus bars are coupled with cells or cell blocks of a battery pack, the voltage may increase across the bus bar and any material contacting the bus bar, such as the bus bar seal material. A bulkhead, as well as other components within the battery module, may be at ground potential, while the bus bars may be at high voltage depending on the number of cells coupled within the module. Because of the electrical potential of the bus bar, materials utilized for the bus bar seal may be limited by the ability to maintain electrical isolation between the bus bar and the bulkhead. For example, a water-based putty or material may be beneficial in providing a complete seal about the bus bar and the bulkhead. However, such a material may provide an electrical path between the components before setting. Accordingly, in embodiments, the bus bar seal material may be characterized by maintaining electrical isolation of the bus bar both in operation as well as during manufacturing operations. When used in overmolding configurations, a settable material may be acceptable when it may be fully set prior to installation in the bus bar tray, or before the bus bar is electrically coupled with cells. 
     Exemplary materials that may be used in bus bar seals according to the present technology may include a variety of materials providing electrical insulation, chemical inertness to effluent materials, and temperature resistance. Exemplary materials may include silicone-containing materials, ceramic materials, thermoplastic-containing materials, polymeric materials, and a range of other materials that may provide one or more electrical or thermal properties. Exemplary materials may include intumescent materials or intumescent coatings on any of the previously noted materials. Exemplary materials may include materials that ablate, including ablation of layers of material, during exposure to high temperature or reactive materials. For example, when exemplary bus bar seal materials are contacted by high-temperature effluents, an outer surface of the bus bar seal may ablate, while interior materials or materials along an opposite side of the bus bar seal may be maintained, or may retain their structural rigidity. Exemplary materials may include composite materials including plastic or other material filled with protective materials. Exemplary materials may include viscous materials forming a seal about a bus bar. Exemplary materials may include foams or expanding materials. Exemplary materials may also include additives or components such as fire retardant additives or materials. 
     In some embodiments the bus bar seal may be insulative and may be configured to withstand voltages greater than or about 100 V, greater than or about 200 V, greater than or about 300 V, greater than or about 400 V, greater than or about 500 V, greater than or about 600 V, greater than or about 700 V, greater than or about 800 V, greater than or about 900 V, greater than or about 1000 V, greater than or about 1200 V, greater than or about 1400 V, greater than or about 1600 V, greater than or about 1800 V, greater than or about 2000 V, greater than or about 2200 V, greater than or about 2400 V, greater than or about 2600 V, greater than or about 2800 V, greater than or about 3000 V, greater than or about 3200 V, greater than or about 3400 V, greater than or about 3600 V, greater than or about 3800 V, greater than or about 4000 V, or greater either as operating voltages or peak voltages. Accordingly, exemplary bus bar seals may be characterized by a comparative tracking index value of greater than or about 250 V, greater than or about 400 V, or greater than or about 600 V. Additionally, bus bar seals according to the present technology may be included in a Performance Level Category of 2, 1, or zero. 
     Creepage and clearance requirements may vary based on the rating of the bus bar material. For example, utilizing a bus bar seal in a Performance Level Category class zero, may afford lower creepage and clearance values than a class  1  material. In embodiments, exemplary bus bar seal materials may afford creepage and clearance tolerances of less than or about 50 mm, and may afford creepage and clearance tolerances of less than or about 45 mm, less than or about 40 mm, less than or about 35 mm, less than or about 30 mm, less than or about 25 mm, less than or about 20 mm, less than or about 19 mm, less than or about 18 mm, less than or about 17 mm, less than or about 16 mm, less than or about 15 mm, less than or about 14 mm, less than or about 13 mm, less than or about 12 mm, less than or about 11 mm, less than or about 10 mm, less than or about 9 mm, less than or about 8 mm, less than or about 7 mm, less than or about 6 mm, less than or about 5 mm, less than or about 4 mm, less than or about 3 mm, less than or about 2 mm, less than or about 1 mm, or less in embodiments. 
     Exemplary bus bar seals or materials may be characterized based on time and/or temperature requirements during events. For example, during a failure event, one or more cells within a cell block may vent materials, which may include high-temperature materials. The cells within a cell block may vent relatively simultaneously, or cells within a cell block may fail in overlapping or sequential events. Depending on the number of cells within a cell block, the venting may occur for a period of time. Accordingly, bus bar seals according to the present technology may be configured to withstand temperatures of greater than or about 100° C. for time periods greater than or about 10 seconds. Additionally, bus bar seals or materials may be characterized by an ability to maintain higher temperatures and/or greater periods of time. For example, bus bar seals may be capable of withstanding temperatures greater than or about 150° C., greater than or about 200° C., greater than or about 250° C., greater than or about 300° C., greater than or about 350° C., greater than or about 400° C., greater than or about 450° C., greater than or about 500° C., greater than or about 550° C., greater than or about 600° C., greater than or about 650° C., greater than or about 700° C., greater than or about 750° C., greater than or about 800° C., greater than or about 850° C., greater than or about 900° C., greater than or about 950° C., greater than or about 1000° C., or higher. 
     Additionally, the bus bar seals may be capable of withstanding any of these temperatures for greater than or about 20 seconds, greater than or about 30 seconds, greater than or about 40 seconds, greater than or about 50 seconds, greater than or about 1 minute, greater than or about 2 minutes, greater than or about 5 minutes, greater than or about 10 minutes, greater than or about 15 minutes, greater than or about 20 minutes, greater than or about 25 minutes, greater than or about 30 minutes, greater than or about 35 minutes, greater than or about 40 minutes, greater than or about 45 minutes, greater than or about 50 minutes, greater than or about 55 minutes, greater than or about 60 minutes, greater than or about 65 minutes, greater than or about 70 minutes, greater than or about 75 minutes, greater than or about 80 minutes, greater than or about 85 minutes, greater than or about 90 minutes, or longer. 
     In some embodiments, the bus bar seals may be configured to withstand a first temperature for a first period of time, and a second temperature less than the first temperature for a second period of time. For example, while the cells of a cell block are venting, the bus bar seal may be contacted by high temperature effluents, which may heat up surrounding components, such as the bus bar. After the effluents have been released from a cell block, such as through a cell block vent, the temperature within the cell may be lower than the initial temperature of the effluents, although components such as a bus bar may still be characterized by an increased temperature for an additional period of time while the heat dissipates. Accordingly, any of the time periods and or temperatures listed may occur as the first time or temperature or the second time or temperature, and exemplary materials may be configured to withstand any of these combinations. 
     Wiring may also connect cells and cell blocks of the present technology, and wire harnesses may extend within a bus bar tray as well. Channels  720 , which may be used for harnesses, may provide additional passageways for effluent materials in embodiments where the channels extend across a bulkhead from one cell block to a next cell block. Accordingly, in some embodiments, a second seal material may be positioned within the tray where a wire harness extends across adjacent cells. The second seal may be characterized by any of the properties of the bus bar seal materials described above. In some embodiments, additional materials may be utilized for the wire harness seals because the wire harnesses may not experience the temperatures of a bus bar, and may not be at a high-voltage potential unlike bus bars. 
       FIG. 8  shows an exploded perspective view of components of a battery pack  800  according to embodiments of the present technology. Battery pack  800  may include any of the components previously described. For example, battery pack  800  may include a structure to contain and support one or more battery cells collected into cell blocks and/or modules as previously described. Battery pack  800  may illustrate a rotated view of battery pack  100  in embodiments. The structure of battery pack  800  may include side rail  111  and side rail  113  coupled proximate opposite sides of a plate structure  114 . A plurality of lateral members  106  may be disposed extending between the side rails, and may be coupled with the side rails such as by welding, bonding, or including an adhesive between the side rails and lateral members. In embodiments, the side rails may include buttresses  231 , which may be coupled on an outer surface with the side rails as illustrated. The battery pack structure may also include a front panel  107  as previously illustrated in  FIG. 1 , as well as rear panel  809 , which may be similar to rear panel  109 , but is illustrated in transparent view in  FIG. 8 . Rear panel  809  is illustrated in this way to provide visual access to components further discussed below that may be otherwise hidden by rear panel  809 . 
     Seated along and running parallel with the lateral members  106  may be a plurality of battery modules  600 . Battery modules  600  are shown in an orientation subsequent installation where they have been inverted from the direction illustrated previously in  FIG. 6 . Accordingly, individual battery cell vents and/or electrical terminals may be positioned facing towards plate structure  114 . The battery modules  600  may be coupled through a top cover  645  and a shroud as previously described to a top portion of lateral members  106 . Lateral members  106  may suspend or at least partially suspend battery modules  600  above plate structure  114  to provide a plenum space between the battery modules  600  and the plate structure  114 . The plenum space may be divided into plenum chambers between the lateral members  106 , which may be coupled with the plate structure  114  either directly or indirectly. For example, a continuous seam weld, spot weld, bond seam, adhesive, fasteners, or other mechanical couplers commonly used to join structural components may be disposed along a length of each lateral member  106  to connect the members to the plate structure  114 . 
     As noted in  FIG. 6 , a thermal interface material may be positioned between battery cells within each cell block and top cover  645 . An additional thermal interface material  810  may be coupled on an opposite surface of top cover  645  to thermal interface material  640  of  FIG. 6 . Thermal interface material  810  may be disposed along battery modules  600  individually, or as a sheet extending along an entire top surface of battery pack  800 , or in other configurations. The sheets of thermal interface material  810  may be included to further conduct or transfer heat from battery modules  600  to heat exchangers  815 , which may be coupled overlying thermal interface material  810 . 
     Heat exchanger  815  may be included as a heat transfer device for further removing heat generated during operation of the system from battery pack  800 . Heat exchanger  815  may include two or more plates coupled together to form a volume there between, and through which a heat transfer fluid may be flowed. The two plates may be extruded aluminum, and may be other materials including metals, plastics, polymeric materials, ceramics, or other materials that may provide properties including flexibility, corrosion resistance, structural rigidity, heat transfer capability, or other useful properties for heat transfer. Interior surfaces of the at least two plates of heat exchanger  815  may include a topography such that when the plates are joined the interior surfaces of the plates may define a volume, such as a number of channels  827 ,  829 , creating a flow system through heat exchanger  815 . Additional plates or materials may be included between outer plates, or within channels defined by the outer plates. For example, materials that increase turbulence within a channel may be included to increase heat transfer to the heat exchanger  815 . 
     The flow system through heat exchanger  815  may be defined from manifolds  819 ,  821  coupled with one end of the heat exchanger  815 . Manifold  819  may be an inlet manifold, and may include an inlet  823  for receiving a heat transfer fluid to the heat exchanger. The manifold  819  may distribute the heat transfer fluid laterally through the manifold as well as through first channels  827 . Channels  827  may run normal to the manifold and extend along a length of heat exchanger  815  from rear panel  809  to front panel  107 . At a distal end of heat exchanger  815  proximate front panel  107 , access may be defined from first channels  827  to second channels  829 . Heat transfer fluid may return through channels  829  in a reverse-parallel flow pattern before being delivered into manifold  821 , which may be a return manifold. Manifold  821  may include an outlet  825 , which may deliver fluid from heat exchanger  815 . 
     Heat exchanger inlet  823  and outlet  825  may couple, respectively, with an inlet distributer  830  and an outlet distributer  832 . Distributers  830 ,  832  may provide access for multiple heat exchangers  815  to be connected to a single fluid distribution system of a battery pack. In embodiments, battery pack  800  may include at least one, two, three, four, or more heat exchangers coupled with individual inlet and outlet distributers. Distributers  830  and  832  may be vertically disposed from one another to limit a depth profile. The distributers may be positioned between a lateral member  106  and rear panel  809  within battery pack  800 . Inlet distributer  830  and outlet distributer  832  may be accessed, respectively, through inlet port  834  and outlet port  836 . Inlet port  834  and outlet port  836  may be coupled with an external fluid management system from battery pack  800 , which may include delivery to a cooled fluid reservoir, a condenser structure, or an additional heat exchanger located outside of battery pack  800  and configured to remove collected heat from the heat transfer fluid. 
     Heat exchangers  815  may be characterized by a number of outer profiles, but in embodiments may be characterized by a substantially planar surface on one or more of top and bottom surfaces of the heat exchanger. Although tubular, ovular, or other rounded or dynamic profiles may be used for heat exchangers  815 , in some embodiments a planar surface may be utilized to increase an area of contact between the heat exchanger  815  and thermal interface material  810 . The planar outer surface may be characterized such that a profile of individual channels is limited on the exterior surface. For example, divisions between interior channels may be contained within an interior region of the heat exchanger, and may not be visible along an outer surface of the heat exchanger  815  to provide a flat or substantially flat surface along a top and bottom surface of the heat exchangers. As illustrated, channels  827  and  829  may include visible portions proximate manifolds  819 ,  821 , although this area may be limited to less than or about 10% of a length across heat exchanger  815 , and may be limited to less than or about 9% of the length, less than or about 8% of the length, less than or about 7% of the length, less than or about 6% of the length, less than or about 5% of the length, less than or about 4% of the length, less than or about 3% of the length, less than or about 2% of the length, less than or about 1% of the length, or less in embodiments. 
     A plurality of apertures  816  may be defined through heat exchanger  815  to provide access to couple heat exchanger  815  to lateral members  106 , and through thermal interface material  810 . The apertures  816  may be located about heat exchanger  815  to limit protrusion within channels defined on the interior of the heat exchanger, and the apertures may be defined channels extending through the heat exchanger, while being fluidly isolated from interior channels defined within the heat exchangers. The apertures may also be located to limit electromagnetic interference from the battery pack  800 . Thermal interface material  810  may be a compressible material, which may include certain flow or deformation characteristics such that compression caused by coupling the heat exchanger  815  to the lateral members  106  may cause regions of thermal interface material  810  to extend about fasteners, bolts, or other mechanical couplers extending through thermal interface material  810 . Accordingly, a gap free or substantially or essentially gap free coupling of the heat exchangers  815  to lateral members  106  may be afforded, and may provide a uniform, substantially uniform, or essentially uniform coupling along a bottom surface of heat exchanger  815  with thermal interface material  810 . 
     In operation, heat transfer fluid included within heat exchanger  815  may be configured to flow normal to a direction of battery cells contained within each module. For example, battery modules  600  may extend parallel with lateral members  106 , and extending between side rail  111  and side rail  113 . Within heat exchanger  815 , channels  827 ,  829  directing heat transfer fluid may run across lateral members  106 , and extend between front panel  107  and rear panel  809 . By this arrangement, as heat is being received from battery cells within a module, the heat may be delivered across a battery cell block and away from a battery module into the next battery module, instead of along a battery module. This arrangement may facilitate heat transfer into lateral members  106 , and may more evenly distribute heat away from battery modules such as malfunctioning modules, which may be producing excessive heat. Although an alternative flow path may be utilized in embodiments in which the heat transfer channels run parallel with individual battery modules, such an arrangement may maintain heat generated within a specific module, and may facilitate excess heat generation into neighboring cells of the battery module. 
     Battery pack  800  may include a lid  840  that extends about heat exchangers  815  and couples with side rails  111 ,  113  as well as front panel  107  and rear panel  109 . In combination with plate structure  114 , the side rails, and the end panels, a liquid tight structure may be afforded. In embodiments, the battery pack  800  may also be substantially air tight or provide a controlled interior environment for the battery pack  800  to limit gaseous transfer from the battery pack  800  except through pack vents as previously discussed. It is to be understood, however, that depending on the materials utilized in the construction, a natural amount of permeation of vapor may occur. The closed pack system may allow improved heat dissipation and solid particle removal from any effluents of a battery cell utilizing the tortuous path defined along the plenum and lateral members as previously described. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20190128
Publication Date: 20220405
Grant Date: 20220405
Priority Date: 20160729
Inventors: MILER, Josef L.
Clarabut, Alexander J.
IJAZ, MUJEEB I.
HALL, JONATHAN
WILHELM, Luke A.
Caulk, Abraham B.
Long, Dirk E.
LI, YU-HUNG
Assignee: APPLE INC
CPC Classifications: [{"code": "H01M10/613", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M50/289", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/209", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/289", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/209", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/30", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02E60/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M50/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/613", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M50/30", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 59579933