Patent Publication Number: US-2020303712-A1

Title: Battery Cell Interconnect and Methods of Manufacture Thereof

Description:
This application is a divisional of U.S. patent application Ser. No. 15/702,660, filed Sep. 12, 2017, which claims benefit of priority to U.S. Provisional Application No. 62/398,427, filed Sep. 22, 2016, which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Battery packs are presently used to provide electrical power to numerous devices, including tools, vehicles, laptop and tablet computers, and mobile phones. In many applications, the physical space required for the battery pack or packs is a crucial design consideration that affects many aspects of a product, including physical size and shape and performance. For example, the available operational time of a portable electronic device and the physical range of an electronic vehicle are both directly affected by the volume of space available to the battery pack and the efficiency of usage of the available volume. In many battery pack applications, it is desirable to safely and efficiently maximize usage of battery pack volume, for example to add electrical capacity to the product, reduce the battery pack size, or to allow for more efficient cooling of a battery pack. 
     A common type of battery is a rechargeable battery with a lithium-based chemistry—for example, a lithium-ion or a lithium-polymer battery. Lithium-ion and lithium-polymer batteries typically contain a cathode current collector; a cathode comprised of an active material, a separator, an anode current collector; and an anode comprised of an active material. The cathode can comprise a cathode coating, and the anode can comprise an anode coating. The cathode, separator, and anode assembly is typically assembled in a cylindrical or prismatic “jelly roll” configuration within a battery casing, with conducting anode and cathode conducting terminals, arranged to protrude into its corresponding active material and allow for a point of electrical connection external the battery casing. A battery casing of existing batteries may typically be neutral, but also may be at cathode (positive) potential or anode (negative) potential. 
     Existing battery packs typically use a bus bar or another similar means including one or more conductor separate from the battery cells, which is usually welded to terminals of a battery cell to form an interconnection system. The bus bar and similar interconnection systems consume space within a battery pack that could be used for other purposes if a more efficient battery interconnect system were to be implemented. 
     SUMMARY 
     A battery cell is configured to maintain electrical communication with other battery cells within a battery pack by being in physical contact with one or more other cells within the pack. A battery cell includes a cathode casing forming all or a majority of the external can of the battery cell. The battery further includes an anode tab covering at least a portion of a face of the battery cell and an insulating layer for electrically isolating the anode tab from the cathode casing. A plurality of such battery cells may be arranged within a battery pack in contact with each other, and may be held in compression. A conduction enhancement layer may be applied between the anode tab of a first cell and the cathode casing of a second cell within the battery pack. 
     Some embodiments include one or more fuses integrated with the anode tab or as part of the cathode casing. One or more heat dissipation elements may be arranged within the battery pack, in contact with the battery cells. Some embodiments include a flexure section built into the anode tab, for example to accommodate a compression force holding a string of battery cells in physical contact. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a cross section of an example battery pack including three cells configured to implement an interconnect according to some embodiments. 
         FIG. 2  illustrates a cross section of two battery cells in electrical communication according to some embodiments. 
         FIG. 3A  is an isometric external view of a battery cell including an anode tab according to some embodiments. 
         FIG. 3B  is an another isometric external view of the battery cell of  FIG. 3A  according to some embodiments. 
         FIG. 3C  is an isometric external view of three battery cells in series contact according to some embodiments. 
         FIG. 4A  is an isometric external view of an additional example battery cell according to some embodiments. 
         FIG. 4B  is another isometric external view of the battery cell of  FIG. 4A  according to some embodiments. 
         FIG. 4C  is another isometric external view of three example battery cells in series contact according to some embodiments. 
         FIG. 5A  illustrates a cross section of a battery cell in contact with a cold plate according to some embodiments. 
         FIG. 5B  illustrates a cross section of a battery cell in contact with multiple cold plates according to some embodiments. 
         FIG. 6A  illustrates a cross section of a battery cell including a fuse according to some embodiments. 
         FIG. 6B  illustrates a cross section of a battery cell including a discharge element according to some embodiments. 
         FIG. 7  is a high-level flowchart illustrating various methods of fabricating a battery cell according to some embodiments. 
     
    
    
     This specification includes references to “one embodiment” or “an embodiment.” The appearances of the phrases “in one embodiment” or “in an embodiment” do not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure. 
     “Comprising.” This term is open-ended. As used in the appended claims, this term does not foreclose additional structure or steps. Consider a claim that recites: “An apparatus comprising one or more processor units . . . .” Such a claim does not foreclose the apparatus from including additional components (e.g., a network interface unit, graphics circuitry, etc.). 
     “Configured To.” Various units, circuits, or other components may be described or claimed as “configured to” perform a task or tasks. In such contexts, “configured to” is used to connote structure by indicating that the units/circuits/components include structure (e.g., circuitry) that performs those task or tasks during operation. As such, the unit/circuit/component can be said to be configured to perform the task even when the specified unit/circuit/component is not currently operational (e.g., is not on). The units/circuits/components used with the “configured to” language include hardware—for example, circuits, memory storing program instructions executable to implement the operation, etc. Reciting that a unit/circuit/component is “configured to” perform one or more tasks is expressly intended not to invoke 35 U.S.C. § 112(f), for that unit/circuit/component. Additionally, “configured to” can include generic structure (e.g., generic circuitry) that is manipulated by software and/or firmware (e.g., an FPGA or a general-purpose processor executing software) to operate in manner that is capable of performing the task(s) at issue. “Configure to” may also include adapting a manufacturing process (e.g., a semiconductor fabrication facility) to fabricate devices (e.g., integrated circuits) that are adapted to implement or perform one or more tasks. 
     “First,” “Second,” etc. As used herein, these terms are used as labels for nouns that they precede, and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.). For example, a buffer circuit may be described herein as performing write operations for “first” and “second” values. The terms “first” and “second” do not necessarily imply that the first value must be written before the second value. 
     “Based On.” As used herein, this term is used to describe one or more factors that affect a determination. This term does not foreclose additional factors that may affect a determination. That is, a determination may be solely based on those factors or based, at least in part, on those factors. Consider the phrase “determine A based on B.” While in this case, B is a factor that affects the determination of A, such a phrase does not foreclose the determination of A from also being based on C. In other instances, A may be determined based solely on B. 
     DETAILED DESCRIPTION 
     The systems and methods described here may implement battery cell interconnection. 
       FIG. 1  illustrates a cross section of an example battery pack including three cells configured to implement an interconnect according to some embodiments. Battery pack  100  may include cells  160   a - 160   c  according to some embodiments. Other embodiments may include any number of cells  160  depending on specific requirements of the application (e.g. an electric vehicle or handheld electronic device) for which the battery pack is meant. Cells  160  may be connected in any combination of series or parallel connections according to a particular desired voltage and energy capacity configuration. 
     According to some embodiments, at least one cell  160   a - 160   c  includes a conductive tab  120   a - 120   c , respectively. Tabs  120   a - 120   c  in a typical embodiment may be an anode (positive) tab connected to one or more anode protrusions of its respective battery cell. In other embodiments, tabs  120   a - 120   c  may instead be at cathode potential. In the example embodiment of  FIG. 1 , a tab  120  may be electrically connected to active material of the cell through a top face of a cell  160  and protrude around the exterior of the cell  160  to form a planar tab. In the example embodiment of  FIG. 1 , cells  160   a - 160   c  are rectangular in shape and tabs  120   a - 120   c  may include a right angle around one corner the exterior of the respective cell. In some embodiments according to  FIG. 1 , a tab  120   a - 120   c  may cover a majority of the exterior of at least one face of the respective cell  160 . 
     One or more of cells  160   a - 160   c  according to some embodiments further include a cell casing (or external can)  130   a - 130   c . According to some embodiments, all or a majority of the cell casing  130  of a particular cell may be at cathode potential. In other embodiments, the polarity of the cell casing  130  and the tab  120  may be reversed such that the tab  120  becomes a cathode tab and the cell casing  130  is at anode potential. 
     According to some embodiments, a cell casing  130  may form all or a majority of the surface area of the external can or container of the cell. In other embodiments, the cathode potential portion may be further limited, for example to a majority of one face of the cell opposite a tab  120 . 
     Configuring a cell casing  130  as a conductor at an anode or cathode potential may allow for more efficient cooling opportunities, as further described herein with reference to  FIGS. 5A and 5B . For example, a larger conductive surface area as a result of such an arrangement as shown and described with reference to  FIG. 1  and elsewhere herein may allow for a more efficient heat sink, resulting for example in reduced thermal concentration within a battery cell or reduced overall operating temperatures. Both of those conditions may prolong the operational life span of a battery cell or its components, such as active material, separators, insulation, electrolyte seals, etc. 
     Insulating layers  110   a - 110   c  may be applied to electrically isolate a tab  120  from a cell casing  130 . An insulating layer  110  may include, for example, a suitable polymer formed or applied around the desired sections. Any substance having current inhibiting properties may be appropriate to form an insulating layer, as one of ordinary skill will understand. In the example embodiments of  FIG. 1 , insulating layers  110   a - 110   c  are shown between respective cell casings  130   a - 130   c  and tabs  120   a - 120   c  on at least one face of the battery and a portion of the top of the battery. 
     At least a portion of one face of a battery cell  160   a - 160   c  may be left uncovered by an insulating layer in order to allow for electrical communication with another cell by being positioned in physical contact with an adjacent cell. For example, in the embodiment shown in  FIG. 1 , tab  120   a  of cell  160   a  physically contacts cell casing  130   b  of cell  160   b  without an intervening insulating layer. Assuming tab  120   a  is configured at an anode potential of cell  160   a  and cell casing  130   b  is configured at a cathode potential of cell  160   b , this physical contact forms a series electrical connection between cells  160   a  and  160   b.    
     Current collectors  140  and  150  according to some embodiments may form electrical terminals of pack  100 . For example, current collector  140  may be electrically coupled to a cathode potential of a string of battery cells  160   a - 160   c . Current collector  150  according to some embodiments may be electrically coupled to an anode potential of a string of battery cells  160   a - 160   c . In other embodiments, the polarity of current collectors  140  and  150  may be reversed. 
     Pack casings  170  and  180  according to some embodiments may form an external enclosure of pack  100 . In some embodiments, pack casings  170  and  180  may be formed of any suitable material, for example a nonconductive plastic or polymer. Pack casings  170  and  180  may in some embodiments be two faces of a continuous enclosure, or may be physically separate faces or plates, as shown in the embodiment of  FIG. 1 . 
     Current collectors  140  and  150  according to some embodiments may form the exclusive or primary conducting terminals of a pack  100 . In some embodiments, current collectors  140  and  150  may protrude from or otherwise be exposed by an opening in a pack casing of pack  100 . The example of  FIG. 1  illustrates current collector  140  protruding through an opening in pack casing  170  and current collector  150  protruding through an opening in pack casing  180 . 
     Cells  160   a - 160   c  according to some embodiments may be held in compression in physical contact with one another. For example, pack casings  170  and  180  may be arranged in some embodiments to provide a compressing force to a string of cells  160   a - 160   c . In some embodiments, current collector  140  and current collector  150  may act as compression plates in combination with or in lieu of compression provided by pack casings  170  and  180 . Other embodiments may use a compression plate or strap (not shown) separate from pack casings  170  and  180  or current collectors  140  and  150  to provide compressive force to a string of battery cells  160   a - 160   c.    
     A compressive force applied to a string of battery cells according to some embodiments may increase efficiency or reliability of the electrical connections between the string of battery cells  160   a - 160   c . In some embodiments, a pressure-sensitive adhesive layer may be applied between various components of battery pack  100  to increase mechanical strength or reliability of the battery pack. For example, an adhesive such as a pressure-sensitive adhesive (“PSA”) may be applied between tab  120   a  and cell casing  130   b —or between similar components of any cells in a battery string—according to some embodiments. In other embodiments, an adhesive may be applied between current collectors  140  and  150  or pack casings  170  and  180  and adjacent cells, or between an insulating layer and a tab  120  or cell casing  130 . 
       FIG. 2  illustrates a cross section of two battery cells in electrical communication according to some embodiments. Example cells  260   a  and  260   b  may include respective tabs  220   a - 220   b , cell casings  230   a - 230   b , and insulating layers  210   a - b  similar to those respective features as described in detail with reference to  FIG. 1 . 
     A conductive layer  270   a - 270   b  may be applied to a face of a respective tab  220   a - 220   b . For example, a conductive layer  270   a  may be applied between tab  220   a  of cell  260   a  and cell casing  230   b  of cell  260   b  to improve electrical conductivity between cells  260   a  and  260   b . In some embodiments, a conductive layer  270   a - 270   b  may be applied to a respective tab  220   a - 220   b  or to a portion of respective cell casing  230   a - 230   b  during fabrication of a respective cell  260   a - 260   b.    
     A conductive layer  270   a - 270   b  may be a conduction aid material, for example Penetrox®. According to some embodiments, a conductive layer  270   a - 270   b  may comprise a metallic or alloy plating. In other embodiments, a conductive layer  270   a - 270   b  may comprise any suitable material for enhancing or promoting electrical conduction, we would be apparent to a person having ordinary skill in the art. 
     According to some embodiments, one or more of cells  260   a - 260   b  may further include one or more respective feed-throughs or penetrations  250   a - 250   c , which protrude into the interior of the respective cell. A feed-through or penetration  250   a - 250   b  may be a conducting material in electrical or physical contact with active material of a respective cell  260   a - 260   b . For example, one or more of feed-throughs or penetrations  250   a - 250   b  may contact anode active material of respective cells  260   a - 260   b.    
     An anode feed-through or penetration  250   a - 250   b  according to some embodiments may be affixed to a respective tab  220   a - 220   b , for example by laser welding or another of numerous possible attachment methods as will be apparent to one having ordinary skill in the art. Where a tab  220   a - 220   b  covers all or a portion of the width of a respective cell  260   a - 260   b , multiple feed-throughs or penetrations  250   a - 250   b  may be possible within a cell, allowing for higher current capacity, better conductive efficiency, or less residual heat within a cell versus a typical design which may include only a single feed-through or penetration or very limited possible penetration area. 
     In other embodiments, a similar improvement to current capacity or conductive efficiency may be realized by increasing the size of a feed-through or penetration, for example by using long feed-throughs or penetrations  250   a - 250   b  positioned inside a substantial portion of a width of a face of a respective battery cell  260   a - 260   b . In some embodiments, an enlarged feed-through or penetration  250   a - 250   b  may be affixed to a respective tab  220   a - 220   b  at multiple points, or via a continuous attachment method such as a continuous longitudinal weld along a length of a feed-through or penetration  250   a - 250   b.    
     Example cells  260   a - 260   b  may include one or more respective seals  240   a - 240   b . According to some embodiments, a seal  240   a - 240   b  may surround a respective feed-through or penetration  250   a - 250   b , for example to prevent electrolytes from escaping a respective battery cell  260   a - 260   b  via an opening in the cell casing fabricated to accommodate an intrusion of a respective feed-through or penetration  250   a - 250   b . A seal  240   a - 240   b  according to some embodiments may be made at least in part of a Perfluoroalkoxy alkane (“PFA”) material or another suitable material as will be apparent to one having ordinary skill in the art. 
     A cell  260   a - 260   b  may include a respective backstop feature  280   a - 280   b  to better accommodate shear forces as a result of battery cells being compressed together according to some embodiments. Backstop feature  280   a - 280   b  may include a staggered “staircase” or other suitable structure built into an insulating layer or cell casing of a respective cell  260   a - 260   b . Although a simple stair structure is illustrated in  FIG. 2 , one of ordinary skill in the art will understand that many different suitable structures may be employed to accommodate increased shear forces. 
     A cell  260   a - 260   b  according to some embodiments may include a respective flexure feature  290   a - 290   b  to add flexibility to a respective tab  220   a - 220   b  for accommodating shear forces as a result of battery cells being compressed together. As illustrated in the example cells of  FIG. 2 , flexure feature  290   a - 290   b  is represented as a notch in respective tab  220   a - 220   b , however one of ordinary skill in the art will appreciate that a tab  220  may be fabricated using any of many possible structures with similar results. 
       FIG. 3A  is an isometric external view of a battery cell including an anode tab according to some embodiments. Cell  330  includes a conducting tab  320 , which according to some embodiments covers a majority of a top and a majority of a side face  325  of cell  330 . 
     An insulating layer  310  covers the remainder of the exterior portion of cell  330  visible in  FIG. 3A . As described elsewhere herein, an insulating layer may be applied to electrically isolate tab  310  from the conductive casing of cell  330 , which may be at cathode potential. 
       FIG. 3B  is an another isometric external view of the battery cell  330  of  FIG. 3A  according to some embodiments.  FIG. 3B  shows a face  335  of cell  330  opposite face  325  illustrated at  FIG. 3A . Cathode casing  340  may be exposed across part or all of face  335  according to some embodiments. The example cell  330  of  FIG. 3B  illustrates cathode casing exposed across a majority of face  335 . 
       FIG. 3C  is an isometric external view of three battery cells in series contact according to some embodiments. According to some embodiments, cells  370   a - 370   c  may be similar or identical to battery cell  330  of  FIGS. 3A and 3B . Tabs  350   a - 350   c  of respective cells  370   a - 370   c  may be configured to contact a cathode casing (not pictured in  FIG. 3C ) of an adjacent cell. For example, as illustrated at  FIG. 3C , tab  350   a  of cell  370   a  may contact a cathode casing of cell  370   b , while tab  350   b  of cell  37   b  may contact a cathode casing of cell  370   c.    
     Insulating layers  360   a - 360   c  of respective cells  370   a - 370   c  are visible at  FIG. 3C . As described elsewhere herein, insulating layers  360  may be applied to electrically isolate tabs  350   a - 350   c  from respective cathode casings (not illustrated at  FIG. 3C ) of cells  370   a - 370   c.    
       FIGS. 4A and 4B  show isometric external views of opposite sides of an additional example battery cell according to some embodiments. Example cell  430  according to some embodiments includes a tab  420  which forms part or a majority of one face of battery cell  430 . Tab  420  according to some embodiments may be an anode tab as described in detail herein. Means of electrical connection of tab  420  to active material of cell  430  similar to other example cells described in detail herein may be fabricated within the cell rather than, for example, the external tab of cells  260   a - 260   b  of  FIG. 2 . 
     The remainder of the exterior boundary of example cell  430  may be a cathode casing  440  as shown in  FIGS. 4A and 4B . A seal  450  may be positioned to electrically isolate tab  420  from cathode casing  440 . Seal  450  according to various embodiments may be any nonconducting material, for example a PFA material, rubberized material, or other material suitable for forming an insulating layer described elsewhere herein. 
     According to some embodiments, tab  420  may form an extruded section. In other embodiments, tab  420  may be recessed from or flush with the plane of cathode casing  440 . In some example embodiments, an extruded tab  420  may aid in maintaining electrical contact with a cathode casing of an adjacent cell. In other embodiments, a similar function may be accomplished by combining a recessed tab  420  section with an extruded cathode casing section at a face of cell  430  opposite tab  420 . 
       FIG. 4C  is another isometric external view of three example battery cells in series contact according to some embodiments. Example cells  470   a - 470   c  may be similar or identical to battery cell  430  of  FIGS. 4A and 4B . Tabs  450   a - 450   c  ( 450   a  and  450   b  not visible) of respective cells  470   a - 470   c  may be configured to contact a cathode casing  460   a - 460   c  of respective adjacent cells  470   a - 470   c . For example, as illustrated at  FIG. 4C , tab  450   a  (not visible) of cell  470   a  may contact cathode casing  460   b  of cell  470   b , while tab  450   b  (not visible) of cell  470   b  may contact cathode casing  460   c  of cell  470   c.    
       FIG. 5A  illustrates a cross section of a battery cell in contact with a cold plate according to some embodiments. Example cell  560  may include a tab  520 , cell casing  530 , insulating layer  510  and conductive layer  570  similar to those described in detail elsewhere herein. 
     Example cell  560  may additionally include a lower cold plate  540  in contact with a bottom face of example cell  560  for conducting heat away from the cell. Cold plate  560  may be formed of aluminum or another material suitable for conducting heat, as one having ordinary skill in the art would understand. A second conductive layer  580  may be applied between cell  560  and lower cold plate  540  according to some embodiments to aid transmission of heat between the cell  560  and lower cold plate  540 . 
       FIG. 5B  illustrates a cross section of a battery cell in contact with multiple cold plates according to some embodiments. Example cell  565  may include a tab  525 , cell casing  535 , insulating layer  515 , and conductive layer  575  as described in detail elsewhere herein. Example cell  565  may additionally include a lower cold plate  545  similar to the lower cold plate described with reference to  FIG. 5A  and a second conductive layer  585  positioned between cell  565  and lower cold plate  545 . 
     Example cell  565  according to some embodiments may further include an upper cold plate  555  positioned in contact with a top face of example cell  565  for conducting heat away from cell  565 . A third conductive layer  595  may be positioned between cell  565  and cold plate  555  for aiding transmission of heat to cold plate  555 . 
     In some embodiments, cold plates may be positioned on different faces of example cells besides the configurations illustrated herein. In still other embodiments, cold plates may be replaced with another means of conducting heat away from a cell, such as thermal channels, a heat exchange system, or liquid cooling system of a surrounding battery pack, as one having ordinary skill in the art will recognize. 
       FIG. 6A  illustrates a cross section of a battery cell including a fuse according to some embodiments. Example cell  660  according to some embodiments may include a tab  620 , cell casing  630 , insulating layer  610 , and conductive layer  670  similar to those described in detail elsewhere herein. 
     Example cell  660  of  FIG. 6A  may further include a fuse  650  for restricting flow of current through cell  660  under certain circumstances. For example, a fuse  650  may be configured to restrict flow of electric current when cell  660  experiences an overcurrent condition, overvoltage condition, overtemperature condition, or other condition as would be apparent to one having ordinary skill in the art. 
     Fuse  650  of example cell  660  is illustrated as being integrated into tab  620 . However, one of ordinary skill in the art will recognize that fuse  650  may be implemented in a different manner or location. For example, fuse  650  according to some embodiments may be integrated into cell casing  630  or at any other suitable location within a conducting path of cell  660 . 
       FIG. 6B  illustrates a cross section of a battery cell including a discharge element according to some embodiments. Example cell  665  according to some embodiments includes a tab  625 , a cell casing  635 , an insulating layer  615 , and a conductive layer  675  similar to those described in detail elsewhere herein. 
     Example cell  665  of  FIG. 6B  may additionally include a discharge element  655  for bleeding excess charge from battery cell  665 . Cell discharge may be desirable for several reasons, such as battery balancing or storage safety. Discharge element  655  may include, for example, one or more resistors or transistors such as field-effect transistors. One of ordinary skill in the art will recognize that other means of discharging a cell may be employed according to materials available and design requirements. 
     Example cell  665  of  FIG. 6B  may additionally include a lower cold plate  645  in contact with discharge element  655  and cell  665 . The conductive properties of cold plate  645  may aid in efficient discharge of cell  665 . Cell  665  according to some embodiments may additionally include a conductive layer  685  positioned between discharge element  655  and lower cold plate  645 . 
       FIG. 7  is a high-level flowchart illustrating various methods of fabricating a battery cell according to some embodiments. Various embodiments may include several or all of the steps described herein with reference to  FIG. 7 , and the order of some steps may be changed according to various embodiments. 
     Step  710  of process  700  includes affixing at least one anode protrusion at least partially within a battery-active-material assembly. The battery-active-material assembly according to some embodiments may be a prismatic or cylindrical “jelly roll” type cathode/separator/anode assembly as described elsewhere herein, or another suitable assembly. According to some embodiments, an anode protrusion affixed at step  710  may be similar to those described with reference to  FIG. 2 . 
     Step  720  of process  700  includes forming a seal about the anode protrusion. The seal plugs any excess opening in a battery casing around the anode protrusion, and may in some embodiments be similar to the electrolyte seals described elsewhere herein. 
     Step  730  includes forming a cathode casing about the seal and battery-active material assembly. The cathode casing may be similar to those described in detail herein. For example, the cathode casing may form a majority of the exterior can of the battery cell. In other embodiments, the casing may instead be at anode potential. In some embodiments, part of the casing may be a nonconducting material or at a neutral potential. 
     Step  740  includes fabricating an anode terminal. The anode terminal may be of various designs and configurations and described in detail and suggested herein, for example an anode tab. Step  750  may include attaching the anode terminal to the battery cell, for example by laser welding to one or more anode protrusions according to various embodiments. 
     Step  760  includes applying an insulating layer similar to various layers described herein. For example, an insulating layer may be applied between the cathode casing and the anode terminal. An insulating layer may additionally be applied to other parts of a battery cell, for example to electrically insulate a battery at the end of a string from a wall of a battery pack enclosure. 
     Step  770  includes applying at least one conduction enhancement layer. For example, as described herein, a conduction enhancement layer may be applied to an external surface of an anode terminal tab at a location that contacts a cathode casing of an adjacent cell, as described in further detail elsewhere herein. Various embodiments may include additional conductive layers, for example between a cell and a cold plate or other battery cooling means. 
     Step  780  includes applying at least one adhesive layer. An adhesive layer may be applied, for example, between an anode terminal tab and an insulating layer, or between a cold plate and a battery cell. The adhesive layer according to various embodiments may be a pressure-sensitive adhesive as described herein or another suitable material. 
     The methods described herein may be implemented in software, hardware, or a combination thereof, in different embodiments. In addition, the order of the blocks of the methods may be changed, and various elements may be added, reordered, combined, omitted, modified, etc. Various modifications and changes may be made as would be obvious to a person skilled in the art having the benefit of this disclosure. The various embodiments described herein are meant to be illustrative and not limiting. Many variations, modifications, additions, and improvements are possible. Accordingly, plural instances may be provided for components described herein as a single instance. Boundaries between various components, operations and data stores are somewhat arbitrary, and particular operations are illustrated in the context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within the scope of claims that follow. Finally, structures and functionality presented as discrete components in the example configurations may be implemented as a combined structure or component. These and other variations, modifications, additions, and improvements may fall within the scope of embodiments as defined in the claims that follow.