Patent Publication Number: US-2022231364-A1

Title: Battery packs having structural members for improving thermal management

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/259,440, filed Jan. 28, 2019, which is a continuation of International Patent Application No. PCT/US2017/044316, filed Jul. 28, 2017, which claims the benefit of U.S. Application Ser. No. 62/368,779, filed Jul. 29, 2016, the disclosures of which are hereby incorporated by reference in their entirety for all purposes. 
    
    
     FIELD 
     This disclosure relates generally to battery packs. 
     BACKGROUND 
     In some designs, battery cells are packaged in groups (called packs) to aggregate overall storage of electrical energy. A battery pack includes a structure that houses or otherwise holds together constituent battery cells. Battery pack design may involve compromises. For example, packaging battery cells closely increases overall energy density, which is beneficial, but may also increase heat transfer between battery cells, which may not be beneficial, at temperature extremes. 
     SUMMARY 
     In some embodiments, a battery pack for packaging an array of battery cells includes a first end-member positioned opposite a second end-member and parallel thereto. The battery pack also includes a first side beam positioned opposite a second side beam and parallel thereto. The first side beam and the second side beam extend longitudinally between the first end-member and the second end-member. A longitudinal member is disposed between the first side beam and the second side beam and defines a plurality of longitudinal rows. The battery pack additionally includes a lateral member disposed between the first end-member and the second end-member to partition the plurality of longitudinal rows into an array of battery cell compartments. A battery cell is disposed within at least one battery cell compartment. At least one of the longitudinal member, the first side beam, and the second side beam are configured to be in tension when the array of battery cell compartments contains a longitudinal row of battery cells extending from the first end-member to the second end-member. 
     In some instances, the battery cell includes an aluminum can. In other instances, the battery cell includes a steel can. 
     In some instances, the battery pack includes a jacket enclosing one or more battery cells disposed within each battery cell compartment and having apertures configured to expose terminals of the one or more battery cells. In some instances, the battery pack includes a sleeve covering one or more battery cells disposed within each battery cell compartment and having a first portion and a second portion. The first portion covers the battery cells along first sides having terminals disposed therein, or covers the battery cells along first sides opposite sides having terminals disposed therein. The first portion may have apertures configured to expose terminals of the battery cells. The second portion covers second sides of the battery cells. The second sides are adjacent the first sides. In some instances, the battery pack includes a base panel having openings configured to expose cell vents of the battery cell. The battery pack also includes a cover panel having apertures configured to expose terminals of the battery cell. In these instances, the longitudinal member divides the lateral member, the first end-member, and the second end-member into separate portions. 
     In other embodiments, a battery pack includes a tubular structure. The tubular structure includes a base member having a bottom wall extending from a first side wall to a second side wall. The tubular structure also includes a cover member coupled to the base member to define a channel therebetween. The cover member has apertures configured to expose terminals of the battery cells. The tubular structure additionally includes a lateral member disposed within the channel to divide the channel into a plurality of battery cell compartments. A first end-member is disposed at a first end of the channel. A second end-member is disposed at a second end of the channel. At least one of the base member and the cover member are configured to be in tension when the plurality of battery cell compartments contains a row of battery cells extending from the first end-member to the second end-member. The battery pack also includes a battery cell disposed within at least one battery cell compartment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1A  is a perspective view of a battery pack for packaging an array of battery cells within structural members that provide thermal management, according to an illustrative embodiment; 
         FIG. 1B  is an exploded view of the battery pack of  FIG. 1A ; 
         FIG. 2A  is a perspective view of a battery pack having structural members that provide thermal management, according to an illustrative embodiment; 
         FIG. 2B  is an exploded view of the battery pack of  FIG. 2A ; 
         FIG. 2C  is an exploded view of a battery pack according to illustrative embodiments; 
         FIG. 2D  is an exploded view of the battery pack of  FIG. 2A , but in which jackets enclose the battery cells, according to an illustrative embodiment; 
         FIG. 2E  is an exploded view of the battery pack of  FIG. 2A , but in which sleeves cover the battery cells, according to an illustrative embodiment; 
         FIG. 2F  is an exploded view of the battery pack of  FIG. 2A , but in which the longitudinal member defines tubular structures within the battery pack, according to an illustrative embodiment; 
         FIG. 3A  is a perspective view of a battery pack having structural members that provide thermal management, according to another illustrative embodiment; and 
         FIG. 3B  is an exploded view of the battery pack of  FIG. 3A . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative 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. 
     The embodiments described herein are directed to structures for housing multiple battery cells, i.e., for forming a battery pack. The battery packs may include structural members that serve multiple functions, such as load-bearing, thermal-management, confinement, battery compression, and so forth. 
     In some embodiments, the structural members improve a stiffness of the battery packs to vertical loads while improving thermal management among a plurality (e.g., array) of battery cell compartments. Such thermal management includes managing heat flow between neighboring battery cells, and in some instances assists a flow of thermal energy out of the battery cells. In another aspect, the structural members are configured to pack the battery cells in a space-efficient arrangement. This space-efficient arrangement increases a volume allocated to storing electrical energy. In yet another aspect, the structural members compress the battery cells when disposed within the plurality of battery cell compartments. Such compression may reduce swelling of the battery cells during operation (e.g., charging, discharging, etc.). Reduced swelling may improve performance, lifetime, or both, of the battery cells. 
     As used herein, the term “thermal management” refers to a regulation of thermal energy flowing into and out of one or more battery cells within a battery pack. The term “thermal management” may also refer to a control or confinement of thermally-induced chemical reactions (and their by-products) that result from electrochemical processes within battery cells. 
     Now referring to  FIG. 1A , a perspective view is presented of a battery pack  100  for packaging an array of battery cells  102  within structural members that provide thermal management, according to an illustrative embodiment.  FIG. 1B  provides an exploded view of the battery pack  100  illustrated in  FIG. 1A . The battery pack  100  includes a first end-member  104  positioned opposite a second end-member  106  and parallel thereto. The first end-member  104  and the second end-member  106  may be disposed normal to a longitudinal axis  108  of the battery pack  100 . The first end-member  104  and the second end-member  106  are operable to apply pressure longitudinally against the array of battery cells  102  within the battery pack  100 . In some embodiments, the first end-member  104 , the second end-member  106 , or both include plate structures. 
     The battery pack  100  also includes a first side beam  110  positioned opposite a second side beam  112  and parallel thereto. The first side beam  110  and the second side beam  112  may be disposed normal to a lateral axis  114  of the battery pack  100 . The first side beam  110  and the second side beam  112  extend longitudinally between the first end-member  104  and the second end-member  106 . Such extension may define a perimeter  116  (see dashed line in  FIG. 1A ) with the first end-member  104  and the second end-member  106 . Exemplary pack  100  has perimeter  116  that is rectangular. In some embodiments, the first side beam  110  and the second side beam  112  apply pressure laterally against the array of battery cells  102  within the battery pack  100 . 
     The first side beam  110  and the second side beam  112  may be coupled to the first end-member  104  and the second end-member  106  via welds, brazes, adhesives (e.g. epoxies, cements, etc.), fasteners (e.g., bolts, rivets, etc.), or some combination thereof. Moreover, cross-sections for the first side beam  110  and the second side beam  112  may vary depending on requirements for stiffness and weight. Non-limiting examples of cross-sections include I-beams, T-beams, C-channels, L-beams, solid squares, hollow squares, solid rectangles, hollow rectangles, solid rounds, and hollow rounds. Other cross-sections are possible. 
     Turning to  FIG. 1B , battery pack  100  in some embodiments includes a longitudinal member  118  disposed between the first side beam  110  and the second side beam  112  and defining a plurality of longitudinal rows. The longitudinal member  118  may be formed using multiple components, as shown in  FIGS. 1A and 1B . In some embodiments, the longitudinal member  118  includes two straps  120 , each having a first end (not shown) and a second end  122  coupled to, respectively, the first endplate  104  and the second endplate  106 . 
     Although a single longitudinal member  118  is depicted in  FIGS. 1A and 1B , this depiction is not intended as limiting. Any number of longitudinal members  118  is possible for the battery pack  100  (i.e., the battery pack  100  includes a plurality of longitudinal members  118 ). In some instances, the longitudinal member  118  is disposed between the first side beam  110  and the second side beam  112  such that the plurality of longitudinal rows have equal widths. In other instances, the longitudinal member  118  is disposed between the first side beam  110  and the second side beam  112  such that the plurality of longitudinal rows have different widths. In general, a position of the longitudinal member  118  may be selected to set a width of one or more longitudinal rows within the battery pack  100 . Non-limiting examples of the longitudinal member  118  include sheets, plates, and slats. Other types of longitudinal members  118  are possible. 
     The battery pack  100  also includes a lateral member  124  disposed between the first end-member  104  and the second end-member  106  to partition the plurality of longitudinal rows into an array of battery cell compartments. The lateral member  124  may be formed using multiple components. In some embodiments, such as that shown in  FIGS. 1A and 1B , the battery pack  100  includes a plurality of lateral members  124 . However, in some embodiments, a single lateral member  124  is possible. In general, a number and position of the lateral member  124  may be selected to determine, respectively, a number and width of one or more lateral rows within the battery pack  100 . 
     In exemplary pack  100 , lateral member(s)  124  connect to first side beam  110  and second side beam  112 . The lateral member  124  may have opposite ends that include a tab. One or both of the opposite ends may include the tab. The tab may assist in coupling the lateral member  124  to the first side beam  110 , the second side beam  112 , or both. In some embodiments, the lateral member  124  includes a first tab (not shown) and a second tab  126  at opposite ends. In these embodiments, the first tab and the second tab  126  protrude through slots  128  in, respectively, the first side beam  110  and the second side beam  112 . In some embodiments, the first tab and the second tab  126  are coupled to, respectively, the first side beam  110  and the second side beam  112  via a fastener  130 . 
     The lateral member  124 , in combination with the longitudinal member  118 , partitions a volume bounded by the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  into an array of battery cell compartments  132  (see solid line). The array of battery cell compartments  132  may correspond to an array of rectangular volumes, such as depicted in  FIGS. 1A and 1B . However, this depiction is not intended as limiting. Other volumetric shapes are possible for the array of battery cell compartments  132 . It will be appreciated that longitudinal members  118  and lateral members  124  may be chosen in any number and position to define any quantity and size of battery cell compartments  132  within the battery pack  100 . By such selection, a space-efficient packaging of battery cells  102  may be achieved within the battery pack  100 . In some embodiments, battery cells  102  are prismatic cells, and the packaging of battery  100  may involve no appreciable gaps between abutting battery cells. 
     In some embodiments, the longitudinal member  118  and the lateral member  124  are formed of sheets or thin plates. Longitudinal member  118  and the lateral member  124  may allow a close packing of adjacent battery cells  102 . Non-limiting examples of materials for the sheets or thin plates include metals (e.g., aluminum, steel, etc.), ceramics (e.g., silica, alumina, etc.), glasses (e.g., borosilicate glass, amorphous carbon, etc.), composites (e.g., carbon-fiber or graphene laminates), and plastics (e.g., polyetherketones, polyphenylene sulfide, etc.). Other materials are possible, including combinations of materials. 
     In some embodiments, at least one of the longitudinal members  118 , the first side beam  110 , and the second side beam  112  are configured to be in tension when the array of battery cell compartments  132  contains a longitudinal row of battery cells  102  extending from the first end-member  104  to the second end-member  106 . In some embodiments, at least one of the lateral member  124 , the first endplate  104 , and the second endplate  106  are configured to be in tension when the array of battery cell compartments  132  contains a lateral row of battery cells  102  extending from the first side beam  110  to the second side beam  112 . 
     Longitudinal tensioning predisposes the end-members  104 ,  106  to compress the battery cells  102  along the longitudinal axis  108 . Similarly, lateral tensioning predisposes the side beams  110 ,  112  to compress the battery cells  102  along the lateral axis  114 . Such compression may reduce swelling of the battery cells  102  during operation (e.g., during charging, discharging, etc.). Reduced swelling may improve performance, lifetime, or both, of the array of battery cells  102 . The tensioning also holds battery cells  102  in place during movement of pack  100 . 
     It will be appreciated that the longitudinal member  118  and the lateral member  124  serve as “webbing” within the volume bounded by the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  (i.e., bounded by the perimeter  116 .) In some embodiments, this “webbing” stiffens the battery pack  100  while simultaneously improving thermal management. Stiffening of the battery pack  100  improves resistance to loads, e.g., vertical loads perpendicular to a plane defined by the longitudinal axis  108  and the lateral axis  114 . This improved resistance allows the battery pack  100  to incorporate longer rows of battery cells  102  (i.e., along the longitudinal axis  108 , the lateral axis  114 , or both) than those associated with conventional battery packs. In some embodiments, stiffness of the battery pack  100  may be modified by altering a longitudinal tension of the longitudinal member  118 , the first side beam  110 , the second side beam  112 , or any combination thereof. In some embodiments, the stiffness of the battery pack  100  may be modified by altering lateral tension of the lateral member  124 , the first end-member  104 , the second end-member  106 , or any combination thereof. 
     The thermal functionality of the “webbing” is aided by a compartmentalized configuration, which helps isolate potential heat sources within controlled volumes. Such controlled volumes are bounded by walls associated with individual battery cell compartments  132 . As discussed below, in some examples, battery cell compartment  132  is walled by a jacket. In some examples, battery cell compartment  132  is walled by a sleeve. In some examples, battery cell compartment  132  is walled by portions of the longitudinal member  118  and the lateral member  124 . These walls optionally include one or more insulative materials to enhance the thermal functionality. In some instances, the walls may include coatings or linings of thermally-insulating material (e.g., porous ceramics), thermally-conductive material (e.g., copper), intumescent material, or any combination thereof. In some instances, the walls may be thermally-coupled to a heat exchanger. This compartmentalized configuration increases volumetric density of battery pack  100  while allowing for proper thermal management. 
     The thermal functionality of the “webbing” impedes thermal energy from propagating between neighboring battery cells  102  and/or battery cell compartments  132 . However, the “webbing” may also conduct thermal energy out of the array of battery cells  102 . For example, and without limitation, the “webbing” may be configured to conduct thermal energy vertically out of the array of battery cells  102 . In some embodiments, such conduction is assisted by anisotropic materials lining the array of battery cell compartments  132  (e.g., graphene sheets coating walls of the array of battery cell compartments  132 ). Anisotropic materials may have a high thermal resistance along a first direction that connects neighboring battery cells  102  and a low thermal resistance along a second direction that is perpendicular to the first direction. 
     The battery cells  102  may be disposed within the battery pack  100  to yield an array of battery cells. In some embodiments, the array of battery cells  102  occupies greater than 84% of the volume enclosed by the perimeter  116 . In some embodiments, the array of battery cells  102  occupies greater than 86% of the volume enclosed by the perimeter  116 . In some embodiments, the array of battery cells  102  occupies greater than 88% of the volume enclosed by the perimeter  116 . In some embodiments, the array of battery cells  102  occupies greater than 90% of the volume enclosed by the perimeter  116 . In some embodiments, the array of battery cells  102  occupies greater than 92% of the volume enclosed by the perimeter  116 . In some embodiments, the array of battery cells  102  occupies greater than 94% of the volume enclosed by the perimeter  116 . In some embodiments, the array of battery cells  102  occupies greater than 96% of the volume enclosed by the perimeter  116 . In some embodiments, the array of battery cells  102  occupies greater than 98% of the volume enclosed by the perimeter  116 . 
     In some embodiments, such as that depicted in  FIGS. 1A and 1B , each battery cell compartment  132  of the array of battery cell compartments  132  is configured to contain two battery cells  102  therein. However, this depiction is not intended as limiting. Other numbers of battery cells  102  may be contained within each battery cell compartment  132 , including differing numbers of battery cells  102  within differing battery cell compartments. In some embodiments, the array of battery cell compartments  132  is configured such that battery cells  102  disposed therein have terminals  134  aligned parallel to the lateral member  124 . 
     Materials for components of the battery pack  100  may be selected by those skilled in the art based on considerations of yield strength, elastic modulus, thermal conductivity, and melting point. Other considerations are possible. 
     In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having a yield strength greater than 250 MPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having a yield strength greater than 275 MPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having a yield strength greater than 300 MPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having a yield strength greater than 325 MPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having a yield strength greater than 350 MPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having a yield strength greater than 375 MPa. 
     In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having an elastic modulus greater than 65 GPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having an elastic modulus greater than 80 GPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having an elastic modulus greater than 95 GPa. In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise a material having an elastic modulus greater than 110 GPa. 
     In some embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise aluminum or an aluminum alloy (e.g., 2024, 6061, 7075, etc.). In other embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise steel (e.g., 304, 316, 1018, 4140, etc.). In still other embodiments, at least one of the first end-member  104 , the second end-member  106 , the first side beam  110 , and the second side beam  112  comprise titanium or a titanium alloy (e.g., Grade 1, Grade 2, Grade 5, Grade 23, etc.). 
     In some embodiments, the longitudinal member  118  and the lateral member  124  comprise a material having a thermal conductivity greater than 10 μm/m·° C. In some embodiments, the longitudinal member  118  and the lateral member  124  comprise a material having a melting point greater than 550° C. In some embodiments, the longitudinal member  118  and the lateral member  124  comprise steel (e.g., 304, 316, 1018, 4140, etc.). In still other embodiments, the longitudinal member  118  and the lateral member  124  comprise titanium or a titanium alloy (e.g., Grade 1, Grade 2, Grade 5, Grade 23, etc.). 
     In some embodiments, battery cells  202  have aluminum cans. The aluminum can may be formed of aluminum or an aluminum alloy (e.g., 2024, 6061, 7075, etc.). In other embodiments, battery cells  202  have steel cans. The steel can may be formed of any type of steel alloy (e.g., 304, 316, 1018, 4140, etc.). 
       FIG. 2A  is a perspective view of exemplary battery pack  200 .  FIG. 2B  is an exploded view illustrating an exemplary construction of battery pack  200  in accordance with some embodiments. Battery pack  200  may include similar components as discussed with regard to battery pack  100 , and may include any of the features or components previously described. For example, battery pack  200  as illustrated may include an array of battery cells  202  disposed in battery cell compartments  232 , which may include or contain a plurality of battery cells including at least two, at least four, at least six, or more battery cells  202  within each battery cell compartment  232 . The battery cell compartments  232  may be at least partially defined by first end-member  204 , second end-member  206 , first side beam  210 , and second side beam  212 , which may define a perimeter  216 . 
     A longitudinal member  218  may be positioned within the battery pack along a longitudinal axis  208 . Longitudinal member  218  may include straps  220  including ends  222 . Additionally, one or more lateral members  224  may be positioned along a lateral axis  214 . Lateral members  224  may define tabs  226  on either or both ends of the structure, which may couple through slots  228  in first side beam  210  and/or second side beam  212 . Fasteners  230  may be used to couple tabs  226  with the associated side beams. Battery cells  202  may have terminals  234  on a side different than that of a cell vent (e.g., an opposite side, adjacent side, top side, etc.). The terminals  234  may be disposed on a top side of the battery cell  202  and the cell vent disposed on a bottom side of the battery cell  202 . 
     Two or more battery cells  202  are disposed within at least one battery cell compartment  232  of the array of battery cell compartments  232 . Optionally, a thermal divider is disposed between adjacent battery cells  202 . The thermal divider may be a thermally-insulating material (e.g., porous ceramics), a thermally-conductive material (e.g., copper), an intumescent material, or any combination thereof. 
       FIG. 2C  illustrates an exploded view of an embodiment of a battery pack  200  according to the present technology. The battery pack may include similar components as previously discussed with regard to  FIG. 2A , while illustrating an additional arrangement of the battery cells  202 . In some embodiments as illustrated, battery cells  202  may be positioned within the battery pack having the terminals  234  facing down. The terminals may be located on a similar surface of the battery cells  202  as the vent, or may be positioned on an opposite or adjacent surface of the battery cells as the vent. 
       FIG. 2D  is an exploded view illustrating an exemplary construction of battery pack  200  in accordance with some embodiments. In the example of  FIG. 2D , jackets  242  in battery pack  200  encloses battery cells  202 , further organizing battery cells into battery cell compartments. The battery pack  200  includes a jacket  242  enclosing one or more battery cells  202  disposed within each battery cell compartment  232 . Jacket  242  optionally includes apertures configured to expose terminals  234  of the one or more battery cells  202 . Optionally, an electrically-insulating member  240  is disposed over the side of the battery cell  202  having terminals  234 . Jacket  242  optionally provides an opening configured to receive battery cells  202 . In  FIG. 2D , the jacket  242  is depicted as enclosing two battery cells  202 . However, this depiction is not intended as limiting. The jacket  242  may enclose any number of battery cells  202 . In some embodiments, the jacket  242  includes steel (e.g., 304, 316, 1018, 4140, etc.). 
       FIG. 2E  is an exploded view illustrating an exemplary construction of battery pack  200  in accordance with some embodiments. In the example of  FIG. 2E , sleeves  244  in battery pack  200  cover battery cells  202 . Battery pack  200  includes a sleeve  244  covering one or more battery cells  202  disposed within each battery cell compartment  232 . Sleeve  244  has a first portion  246  and a second portion  248 . The first portion  246  covers the battery cells  202  along first sides having terminals  234  disposed therein. The first portion  246  has apertures configured to expose terminals  234  of the battery cells  202 . The second portion  248  covers second sides of the battery cells  202 . The second sides are adjacent the first sides and may be perpendicular thereto. In  FIG. 2E , the sleeve  244  is depicted as enclosing two battery cells  202 . However, this depiction is not intended as limiting. The sleeve  244  may enclose any number of battery cells  202 . In some embodiments, the sleeve  244  includes steel (e.g., 304, 316, 1018, 4140, etc.). Optionally, an electrically-insulating member  240  is disposed over the side of the battery cell  202  having terminals  234 . 
       FIG. 2F  is an exploded view illustrating an exemplary construction of battery pack  200  in accordance with some embodiments. In the example of  FIG. 2F , longitudinal member  218  is a tubular structure. Furthermore, battery pack  200  includes base panel  236  and a cover panel  238 . The base panel  236  has openings configured to expose cell vents of the battery cell  202 . The cover panel  238  has apertures configured to expose terminals  234  of the battery cell  202  in a first orientation, and may not include apertures in a second orientation where terminals  234  are on an opposite surface of the battery cells  202  where they may face base panel  236 . Optionally, an electrically-insulating member  240  is disposed over the side of the battery cell  202  having terminals  234 . In embodiments, the longitudinal member  218  divides the lateral member  224 , the first end-member  204 , and the second end-member  206  into separate portions. Such division partitions the perimeter  216  into a plurality of conduits  250 . Portions of the lateral member  224  may function as bulkheads within the plurality of conduits  250 . In  FIG. 2F , the longitudinal member  218  divides the lateral member  224 , the first end-member  204 , and the second end-member  206  into two conduits  250 . However, this depiction is not intended as limiting. Multiple longitudinal members  218  may be incorporated into the battery pack  200  to define any number of conduits  250   
     Now referring to  FIG. 3A , a perspective view is presented of a battery pack  300  having structural members that provide thermal management, according to some embodiments.  FIG. 3B  provides an exploded view of the battery pack  300  illustrated in  FIG. 3A . The battery pack  300  includes a tubular structure  302 , which in certain variations, may include a plurality of tubular structures  302  disposed side-by-side.  FIG. 3A  depicts a specific variation where two tubular structures  302  are disposed side-by-side. However, this depiction is not intended as limiting. The tubular structure  302  may be aligned parallel to a longitudinal axis  304  of the battery pack  300 . Each tubular structure  302  includes a base member  306  having a bottom wall  308  extending from a first side wall  310  to a second side wall  311 . In some embodiments, such as that shown in  FIGS. 3A and 3B , an exterior-facing side wall  312  of the base member  306  includes a side beam  314 . 
     Each tubular structure  302  also includes a cover member  316  coupled to the base member  306  so as to define a channel  318  therebetween. The channel  318  may have a cross-section  320  of any type, including a circular cross-section, an elliptical cross-section, a hexagonal cross-section, a square cross-section, and a rectangular cross-section. The cover member  316  has apertures configured to expose terminals of the battery cells. Each tubular structure  302  additionally includes a lateral member  322  disposed within the channel  318  to divide the channel  318  into a plurality of battery cell compartments  324 . The lateral member  322  may serve as a bulkhead within the channel  318 . In some embodiments, such as that shown in  FIGS. 3A and 3B , the plurality of tubular structures  302  include a plurality of lateral members  322  within each channel  318 . 
     It will be appreciated that any number of lateral members  322  may be disposed within the channel  318 . Moreover, the lateral members  322  may be spaced so as to partition any combination of volumetric shapes therein. In this manner, the plurality of battery cell compartments  324  can be configured to have any number and combination of shapes within the channel  318 . The plurality of battery cell compartments  324  may be different for each channel  318 . In some embodiments, each of the plurality of battery cell compartments  324  is configured to contain two battery cells therein. In some embodiments, the plurality of battery cell compartments  324  is configured such that battery cells disposed therein have terminals aligned parallel to the lateral member  322 . 
     A first end-member  326  is disposed at a first end  352  of the channel  318 . Similarly, a second end-member  327  is disposed at a second end  353  of the channel  318 . The end-members  326 ,  327  are operable to apply pressure longitudinally against battery cells and lateral members  322  disposed within the channel  318 . In some embodiments, at least one of the base member  306  and the cover member  316  are configured to be in tension when the plurality of battery cell compartments  324  contains a row of battery cells extending from the first end-member  326  to the second end-member  327 . This tension predisposes the end-members  326 ,  327  to compress battery cells within the plurality of battery cell compartments  324  (i.e., longitudinally, laterally, vertically, or a combination thereof). Such compression may reduce swelling of battery cells within the channel  318  during operation (e.g., during charging, discharging, etc.) Reduced swelling may improve performance, lifetime, or both, of battery cells utilized by the battery pack  300  to store and deliver electrical power. 
     In embodiments having the plurality of tubular structures disposed side-by-side, the battery pack  300  also includes a union member  328  disposed along a seam between adjacent tubular structures  302  and coupled to the adjacent tubular structures  302 . Such coupling may involve any component of the tubular structure  302  (e.g., the base member  306 , the cover member  316 , etc.) Non-limiting examples of the union member  328  include rods, pipes, beams, strips, plates, brackets, bars, trusses, wire, and cable. Other types of union members  328  are possible. Coupling of the union member  328  to the adjacent tubular structures  302  may involve welds, brazes, adhesives (e.g. epoxies, cements, etc.), fasteners (e.g., pins, bolts, rivets, etc.), or some combination thereof. In some embodiments, such as that shown in  FIGS. 3A and 3B , the union member  328  is a strip disposed along the seam. The strip may be welded to the adjacent tubular structures  302 . 
     One or more battery cells  330  may be disposed within the channel  318  to yield the battery pack  300 . In some variations, the battery cells  330  have terminals  332  on a side different than that of a cell vent (e.g., an opposite side, adjacent side, top side, etc.). In some variations, the battery cells  330  have terminals  332  on a similar surface as a cell vent. In some variations, the base member  306  may include a plurality of openings  334  configured to expose cell vents of the battery cells  330 . In some variations, an electrically-insulating member  336  is disposed on a side of the battery cells  330  having terminals  332 . 
     In some embodiments, the battery cells  330  occupy greater than 84% of a volume within the channel  318 . In some embodiments, the battery cells  330  occupy greater than 86% of the volume within the channel  318 . In some embodiments, the battery cells  330  occupy greater than 88% of the volume within the channel  318 . In some embodiments, the battery cells  330  occupy greater than 90% of the volume within the channel  318 . In some embodiments, the battery cells  330  occupy greater than 92% of the volume within the channel  318 . In some embodiments, the battery cells  330  occupy greater than 96% of the volume within the channel  318 . In some embodiments, the battery cells  330  occupy greater than 98% of the volume within the channel  318 . 
     In general, the tubular structure  302  stiffens the battery pack  300  longitudinally while providing a thermal functionality. Stiffening of the battery pack  300  improves resistance to loads, e.g., vertical loads perpendicular to the base member  306  or the cover member  316 . This improved resistance allows the battery pack  300  to incorporate longer rows of battery cells  330  than those associated with conventional battery packs. In some embodiments, stiffness of the battery pack  300  may be modified by altering a longitudinal tension of the base member  306 , the cover member  316 , or both. 
     The thermal functionality of the tubular structure  302  is aided by the lateral member  322 , which segregates battery cells  330  within the tubular conduit  302 . Such segregation produces the plurality of battery cell compartments  324 . The plurality of battery cell compartments  324  isolates potential heat sources within controlled volumes for improved thermal management. These volumes are bounded by walls associated with individual battery cell compartments  324  (i.e., the lateral members  322  and portions of the base member  306  and the cover member  316 ). In some instances, the walls may include coatings or linings of thermally-insulating material (e.g., porous ceramics), thermally-conductive material (e.g., copper), intumescent material, or any combination thereof. In some embodiments, the walls may be thermally-coupled with a heat exchanger. 
     In some embodiments, the battery pack  300  includes a battery cell  330  disposed within at least one battery cell compartment  324 . The battery cell  330  may have terminals on a side different than that of a cell vent (e.g., an opposite side, adjacent side, top side, etc.). The battery cell  330  may also have an electrically-insulating member  336  disposed on the side of the battery cell  330  having terminals  332 . In some instances, the battery cell  330  occupies at least 90% of a volume of a battery cell compartment  324 . In some instances, the battery cell  330  occupies at least 92% of a volume of a battery cell compartment  324 . In some instances, the battery cell  330  occupies at least 94% of a volume of a battery cell compartment  324 . In some instances, the battery cell  330  occupies at least 96% of a volume of a battery cell compartment  324 . In some instances, the battery cell  330  occupies at least 98% of a volume of a battery cell compartment  324 . 
     In some embodiments, the battery pack  300  includes two or more battery cells  330  disposed within at least one battery cell compartment of the plurality of battery cell compartments  324 . A thermal divider may be disposed between adjacent battery cells  330 . The thermal divider may be a thermally-insulating material (e.g., porous ceramics), a thermally-conductive material (e.g., copper), an intumescent material, or any combination thereof. In some instances, the battery cells  330  may each have terminals on a side opposite that of a cell vent. In some instances, the electrically-insulating member  336  is disposed on the side of each battery cell  320  having terminals  332 . 
     Materials for components of the battery pack  300  may be selected by those skilled in the art based on considerations of yield strength, elastic modulus, thermal conductivity, and melting point. Other considerations are possible. 
     In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having a yield strength greater than 250 MPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having a yield strength greater than 275 MPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having a yield strength greater than 300 MPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having a yield strength greater than 325 MPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having a yield strength greater than 350 MPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having a yield strength greater than 375 MPa. 
     In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having an elastic modulus greater than 65 GPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having an elastic modulus greater than 80 GPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having an elastic modulus greater than 95 GPa. In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise a material having an elastic modulus greater than 110 GPa. 
     In some embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise aluminum or an aluminum alloy (e.g., 2024, 6061, 7075, etc.). In other embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise steel (e.g., 304, 316, 1018, 4140, etc.). In still other embodiments, at least one of the base member  306 , the cover member  316 , the lateral member  322 , the first end-member  326 , and the second end-member  327  comprise titanium or a titanium alloy (e.g., Grade 1, Grade 2, Grade 5, Grade 23, etc.). 
     In some embodiments, at least one of the base member  306 , the cover member  316 , and the lateral member  322  comprise a material having a thermal conductivity greater than 10 μm/m·° C. In some embodiments at least one of the base member  306 , the cover member  316 , and the lateral member  322  comprise a material having a melting point greater than 550° C. In some embodiments, at least one of the base member  306 , the cover member  316 , and the lateral member  322  comprise steel (e.g., 304, 316, 1018, 4140, etc.). In still other embodiments, at least one of the base member  306 , the cover member  316 , and the lateral member  322  comprise titanium or a titanium alloy (e.g., Grade 1, Grade 2, Grade 5, Grade 23, etc.). 
     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.