Patent Publication Number: US-11660971-B2

Title: System for arranging and coupling battery cells in a battery module

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 14/065,172, filed Oct. 28, 2013, which is a Continuation-In-Part of U.S. patent application Ser. No. 12/368,938, now U.S. Pat. No. 8,567,915, filed Feb. 10, 2009, which claims benefit of and priority to U.S. Provisional Patent Application No. 61/101,985, filed Oct. 1, 2008, and U.S. Provisional Patent Application No. 61/146,994, filed Jan. 23, 2009, U.S. Pat. No. 8,567,915 is also a Continuation-In-Part of International Application No. PCT/US2007/017785 filed Aug. 10, 2007, which claims the priority to U.S. Provisional Patent Application No. 60/857,345, filed Aug. 11, 2006, all of which are incorporated by reference in their entireties for all purposes. 
    
    
     BACKGROUND 
     The present disclosure relates to the field of batteries and battery systems. More specifically, the present disclosure relates to integrally formed terminals for batteries or cells (e.g., lithium-ion batteries). 
     It is known to provide batteries or cells for use in vehicles such as automobiles. For example, lead-acid batteries have been used in starting, lighting, and ignition applications. More recently, hybrid electric vehicles are being developed which utilize a battery (e.g., a lithium-ion or nickel-metal-hydride battery) in combination with other systems (e.g., an internal combustion engine) to provide power for the vehicle. 
     It is known that a battery generally includes two terminals (e.g., a positive terminal and a negative terminal, etc.) through which the battery is electrically connected to other batteries or other components. A battery may have terminals that protrude from the battery surface and/or have a casing that acts as a terminal. These terminals are provided as separate elements that are coupled to the battery (e.g., by welding to a battery cover). This adds an additional step to the manufacturing process, as well as increased cost. The integrity of this weld or other coupling mechanism may present issues over the life of the battery. 
     Battery systems or assemblies include a number of batteries or cells electrically coupled to each other and/or to other elements of the system. Such cells are conventionally coupled together using conductive members (e.g., bus bars). Such conductive members may be welded to the terminals of the batteries or secured using fasteners. It would be advantageous to eliminate the need for such conductive members to remove the additional cost and manufacturing time associated with such components (e.g., to reduce the number of parts in the battery system and to eliminate the need to handle and assemble the components during manufacturing). 
     Accordingly, it would be advantageous to provide a battery that includes one or more terminals that are integrally formed with the body or cover of the battery. It would also be advantageous to configure the terminals so they can be directly coupled to terminals of adjacent batteries. 
     SUMMARY 
     Certain embodiments commensurate in scope with the originally claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the disclosure, but rather these embodiments are intended only to provide a brief summary of certain disclosed embodiments. Indeed, the present disclosure may encompass a variety of forms that may be similar to or different from the embodiments set forth below. 
     One embodiment relates to a battery including a housing having a central longitudinal axis. The battery also includes a cover coupled to the housing and a first flange integrally formed with the cover. The first flange is configured to act as a first terminal for the battery. At least a portion of the first flange extends away from the housing in a direction generally perpendicular to the central longitudinal axis. The first flange is configured for electrical coupling with a terminal of an adjacent battery in a battery system. 
     Another embodiment relates to a battery module including a plurality of electrochemical cells. Each of the cells comprise a housing having a longitudinal axis and a lid coupled to the housing. The lid comprises a member configured to act as a first terminal for the cell. At least a portion of the member extends away from the housing in a direction generally perpendicular to the longitudinal axis. The member is conductively coupled to a terminal of an adjacent cell. 
     Another embodiment relates to a method of producing a battery module including providing a plurality of electrochemical cells. Each of the cells comprises a housing having a longitudinal axis and a cover coupled to the housing at a first end of the cell. The cover comprises a member configured to act as a first terminal for the cell. At least a portion of the member extends away from the housing in a direction generally perpendicular to the longitudinal axis. The method also includes coupling the member of one of the plurality of cells to a terminal of an adjacent cell. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG.  1    is a perspective view of a vehicle having a battery system according to an embodiment; 
         FIG.  1 A  is a schematic cutaway view of a hybrid electric vehicle according to an embodiment; 
         FIG.  2    is a perspective view of a battery system according to an embodiment; 
         FIG.  2 A  is a cutaway perspective view of a battery system according to an embodiment; 
         FIG.  3    is a perspective view of a battery or cell according to an embodiment; 
         FIG.  4    is an exploded view of the battery of  FIG.  3    according to an embodiment; 
         FIG.  5    is a perspective view of a cover for a battery according to an embodiment; 
         FIG.  6    is a top view of the cover of  FIG.  5    according to an embodiment; 
         FIG.  7    is a cross-section view of the cover of  FIG.  6    taken along line  7 - 7  according to an embodiment; 
         FIG.  8    is a perspective view of a battery according to an embodiment; 
         FIG.  9    is a perspective view of the cover of the battery of  FIG.  8    according to an embodiment; 
         FIG.  10    is a view of multiple batteries connected together according to an embodiment; 
         FIGS.  11 A- 11 G  are views of a battery according to various embodiments; 
         FIG.  12    is an exploded view of a battery according to an embodiment; 
         FIG.  13    is an exploded view of a battery according to an embodiment; 
         FIG.  14    is a perspective view of a first electrochemical cell coupled to a second electrochemical cell with a bus bar according to an embodiment; 
         FIG.  15    is a perspective view of a bus bar coupled to a terminal of an adjacent electrochemical cell according to an embodiment; 
         FIG.  16    is a perspective view of a portion of a battery module having a first electrochemical cell coupled to a second electrochemical cell with the bus bar as shown in  FIG.  15    according to an embodiment; 
         FIG.  17    is a cutaway perspective view of a portion of an electrochemical cell shown without electrodes according to an embodiment; 
         FIG.  18    is an exploded view of the electrochemical cell as shown in  FIG.  17    according to an embodiment; 
         FIG.  19    is a perspective view of a lid having an integral bus bar coupled to a terminal according to an embodiment; 
         FIG.  20    is a perspective view of the lid as shown in  FIG.  19    according to an embodiment; 
         FIG.  21    is a perspective view of a battery module according to an embodiment; 
         FIG.  22    is a perspective view of the battery module as shown in  FIG.  21    with an upper tray removed according to an embodiment; 
         FIG.  23    is a perspective view of a plurality of electrochemical cells provided in an upper tray according to an embodiment; 
         FIG.  24    is a perspective view of a plurality of electrochemical cells provided in an upper tray according to an embodiment; 
         FIG.  25    is a top view of the upper tray as shown in  FIG.  21    according to an embodiment; 
         FIG.  26    is a perspective view of the upper tray as shown in  FIG.  21    according to an embodiment; 
         FIG.  27    is a bottom view of the upper tray as shown in  FIG.  21    according to an embodiment; 
         FIG.  28    is a bottom perspective view of the upper tray as shown in  FIG.  21    according to an embodiment; 
         FIG.  29    is a top view of an arrangement of battery cells in a battery module according to an embodiment; 
         FIG.  30    is a top view of another arrangement of battery cells in a battery module according to an embodiment; and 
         FIG.  31    is a top view of another embodiment of battery cells in a battery module according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG.  1   , a vehicle  12  is shown according to an embodiment and includes a battery system  14 . The size, shape, configuration, and location of battery system  14  and the type of vehicle  12  may vary according to various embodiments. For example, while vehicle  12  in  FIG.  1    is shown as an automobile, according to various embodiments, vehicle  12  may comprise a wide variety of differing types of vehicles including, among others, motorcycles, buses, recreational vehicles, boats, and the like. According to an embodiment, vehicle  12  has a battery system  14  for providing all or a portion of the motive power for the vehicle  12 . Such a vehicle can be an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or other type of vehicle using electric power for propulsion (collectively referred to as “electric vehicles”). 
     Although the battery system  14  is illustrated in  FIG.  1    as being positioned in the trunk or rear of the vehicle  12 , according to other embodiments, the location of the battery system  14  may differ. For example, the position of the battery system  14  may be selected based on the available space within the vehicle  12 , the desired weight balance of the vehicle  12 , the location of other components used with the battery system  14  (e.g., battery management systems, vents or cooling devices, etc.), and a variety of other considerations. 
       FIG.  1 A  illustrates a cutaway schematic view of a vehicle  100  provided in the form of a PHEV according to an embodiment. A battery system  102  is provided toward the rear of the vehicle  100  proximate to a fuel tank  104  (battery system  102  may be provided immediately adjacent to the fuel tank  104  or may be provided in a separate compartment in the rear of the vehicle  100  (e.g., a trunk) or may be provided elsewhere in the vehicle  100 ). An internal combustion engine  106  is provided for times when the vehicle  100  utilizes gasoline power to propel itself. An electric motor  108 , a power split device  112 , and a generator  114  are also provided as part of the vehicle drive system of vehicle  100 . The vehicle  100  may be powered or driven by just the battery system  102 , by just the engine  106 , or by both the battery system  102  and the engine  106 . 
     It should be noted that other types of vehicles and configurations for the vehicle electrical system may be used according to other embodiments, and that the schematic illustration of  FIG.  1 A  should not be considered to limit the scope of the subject matter described in the present application. 
     Referring to  FIG.  2   , battery system  14  is shown according to an embodiment. Battery system  14  includes a plurality of electrochemical cells or batteries, shown as batteries  10  (e.g., lithium-ion batteries, NiMH batteries, lithium polymer batteries, etc.). Batteries  10  may be positioned within a housing that may include such features as a battery management system, a cooling fan, plenum assembly, etc. Other configurations of battery system  14  may be used in accordance with various other embodiments. 
     Referring to  FIG.  2 A , a battery system  116  is shown according to an embodiment and is responsible for packaging or containing a battery module  117  containing electrochemical cells or batteries  118 , connecting the electrochemical cells  118  to each other and/or to other components of the vehicle electrical system, and regulating the electrochemical cells  118  and other features of the battery system  116 . For example, the battery system  116  may include features that are responsible for monitoring and controlling the electrical performance of the battery system  116 , managing the thermal behavior of the battery system  116 , containment and/or routing of effluent (e.g., gases that may be vented from a cell  118 ), and other aspects of the battery system  116 . 
     Referring to  FIG.  2 A , the battery module  117  includes a plurality of electrochemical cells or batteries  118  (e.g., lithium-ion batteries, nickel-metal-hydride cells, lithium polymer cells, etc., or other types of electrochemical cells now known or hereafter developed). According to an embodiment, the electrochemical cells  118  are generally cylindrical lithium-ion cells configured to store an electrical charge. According to other embodiments, cells  118  could have other physical configurations (e.g., oval, prismatic, polygonal, etc.). The capacity, size, design, and other features of the cells  118  may also differ from those shown according to other embodiments. According to an embodiment, the cells  118  each have at least one terminal  119  located at an end thereof. According to another embodiment, the cells each have two terminals  119  (e.g., a first or positive terminal, and a second or negative terminal) located at an end thereof. 
     According to various embodiments, the size, shape, and location of the battery module  117  or battery system  116 , the type of vehicle  100 , the type of vehicle technology (e.g., EV, HEV, PHEV, etc.), and the battery chemistry, among other features, may differ from those shown or described. 
     Although illustrated in  FIG.  2 A  as having a particular number of electrochemical cells  118 , it should be noted that according to other embodiments, a different number and/or arrangement of electrochemical cells  118  may be used depending on any of a variety of considerations (e.g., the desired power for the battery system  116 , the available space within which the battery system  116  is designed to fit, etc.). 
     According to an embodiment, a series of members or elements in the form of trays  140  or similar structures are provided to contain the various cells  118  in relation to each other. The trays  140  may be made of a polymeric material or other suitable materials (e.g., electrically insulative materials). The trays  140  may also include features to provide spacing of the cells  118  away from the surface of the trays  140  and/or from adjacent cells  118 . A housing or cover  142  and a base plate (not shown) may be provided to partially or completely surround or enclose the cells  118  and trays  140 . 
     While  FIG.  2 A  shows an embodiment of a battery module  117 , it should be understood that the battery module  117  is not limited to any particular arrangement as will be appreciated by those reviewing this disclosure. For instance, while the battery module  117  shown in  FIG.  2 A  is shown with horizontally oriented cells  118  arranged back-to-back in two banks or groups by parallel frame members (i.e., trays  140 ), it should be understood that the battery module  117  may have many different configurations. For example, the cells  118  may also be generally vertical, be several separate groups, or arranged in other configurations. Furthermore, different numbers and types (e.g., nickel-metal-hydride, etc.) of cells  118  may be used. The cover  142  may include features (e.g., sidewalls, etc.) that are intended to receive and arrange the cells  118 . 
     Referring now to  FIGS.  3 - 4   , a battery or cell  10  is shown according to an embodiment. Battery  10  is generally cylindrical and comprises a container  20  (e.g., housing, casing, can, etc.), a cover or lid  30  coupled to container  20 , a member or element in the form of an insulator  40  that separates container  20  and cover  30 , and one or more terminals  50 . Container  20  is a generally hollow body (e.g., can, cup, canister, etc.) made of aluminum or another conductive material. Container  20  has provided therein electrodes  60  and an electrolyte (not shown) and may act as a terminal  50  for battery  10 . According to an embodiment, battery  10  is a lithium-ion battery, although those reviewing this disclosure will recognize that other types of batteries may also use features described herein (e.g., nickel-metal-hydride batteries, lithium-polymer batteries, etc.). 
     Cover  30  is a generally planar member or element (e.g., lid, cap, top, etc) that encloses electrodes  60  and the electrolyte in container  20  and is conductively separated from container  20  by insulator  40 . According to an embodiment, cover  30  is aluminum or another suitable conductive material and is conductively coupled to electrode  60  in battery  10 . 
     Referring to  FIGS.  5 - 7   , according to an embodiment, terminal  50  is a protrusion or extension that is extruded, drawn, molded, cast, or otherwise formed as an integral part of cover  30 . According to other embodiments, terminal  50  may be a variety of shapes other than that shown in  FIGS.  5 - 7    (e.g. cylindrical, rectangular, trapezoidal, etc.) and may be provided in a variety of positions (e.g., central, near the edge, etc.) and orientations. According to still other embodiments, terminal  50  may be provided on container  20  or terminals  50  may be provided both on container  20  and on cover  30 . Terminal  50  may be further machined or shaped to provide a feature for coupling terminal  50  to wires, sockets, bus bars, or other components. It should be noted that terminal  50  can either follow the contour of the cover  30  or can be flattened so that a standard spade connector can be placed flat on the surface of the terminal  50  according to other embodiments. 
     Referring now to  FIG.  8   , a battery  110  is shown according to an embodiment. Battery  110  is generally cylindrical and comprises a container or housing  120  and a cover or lid  130  coupled to container  120 . Container  120  is a generally thin-walled hollow body (e.g., a can, cup, canister, etc.) made of aluminum or another conductive material and is conductively coupled to an electrode (e.g., cathode or anode). Container  120  holds electrodes and an electrolyte (not shown) and may act as a terminal for battery  110 . Container  120  includes a side wall  122  with a rim  123 . Container  120  also includes a feature shown as a flange  124  (e.g., a tab, flap, projection, extension, protrusion, projection, lip, overhang, protuberance, etc.). 
     Flange  124  is a generally flat member (e.g., a tab, flap, projection, extension, protrusion, projection, lip, overhang, protuberance, etc.) that is integrally formed with side wall  122  and extends upward past rim  123 . Flange  124  may be bent and have a vertical portion  126  and a horizontal portion  128  that extends beyond side wall  122  (e.g., in a direction generally perpendicular to the axial or longitudinal direction for the cell). Flange  124  is configured to engage flange  134  on cover  130  of an adjacent battery  110  (described in more detail below with respect to  FIG.  10   ). 
     Cover  130 , as shown in  FIG.  9   , is a generally flat body (e.g., lid, cap, top, etc.) that encloses electrodes and electrolyte in container  120  and is conductively separated from container  120  with an insulator (not shown). According to an embodiment, cover  130  is aluminum or another suitable conductive material and is conductively coupled to an electrode in battery  110 . Cover  130  comprises a generally flat, circular surface or body  132 , and a generally vertical side wall  133  that extends upward from and substantially perpendicular to surface  132 . Side wall  133  is a curved feature that substantially follows the contour of side wall  122  of container  120  and has an outer diameter less than the inner diameter of side wall  122 . Cover  130  is configured to fit inside the open end of container  120 . Cover  130  also includes a feature shown as flange  134 . 
     Flange  134  is a generally flat member (e.g., tab, flap, projection, extension, etc.) that is integrally formed with side wall  133  and extends upward therefrom. Flange  134  may be bent and have a vertical portion  136  and a horizontal portion  138  that extends outward past side wall  133  in a direction generally opposite horizontal portion  128  of flange  124 . 
     Referring now to  FIG.  10   , a plurality of batteries  110  are shown connected in series to form a portion of a battery module or battery system. According to an embodiment, vertical portion  136  of flange  134  on cover  130  is longer than vertical portion  126  of flange  124  on container  120 . When a first battery  110  is coupled to a second battery  110  (e.g., by welding), horizontal portion  138  of flange  134  on one battery  110  rests on horizontal portion  128  of flange  124  on another battery  110 . According to an embodiment, flanges  124 ,  134  are welded together. According to other embodiments, flanges  124 ,  134  may be coupled in another suitable manner, either permanently or temporarily (e.g., bolted, riveted, crimped, clamped, etc.). Flanges  124 ,  134  may act as terminals that can directly and conductively couple two batteries together, eliminating the need for a separate member to conductively couple the batteries. 
     Referring now to  FIGS.  11 A- 11 G , a number of batteries are shown according to various embodiments. Each battery comprises a first terminal and a second terminal. According to the various embodiments, one or both of the terminals may be integrally formed as a part of the cover and/or container of the battery.  FIG.  11 A  illustrates a battery  210  with terminals  220 ,  230  that are located on the same end of battery  210  and are substantially smooth pins.  FIG.  11 B  illustrates a battery  310  with a first terminal  320  on one end and a second terminal  330  on an opposite end. According to an embodiment, terminals  320 ,  330  are substantially smooth pins. 
       FIG.  11 C  shows an embodiment of a battery  410  with terminals  420 ,  430  that are located on the same end of battery  410  and are generally thin flat members (e.g., blades). According to an embodiment, terminals  420 ,  430  are generally parallel. According to other embodiments, terminals  420 ,  430  may be at some other angle relative to each other (e.g., perpendicular to each other as in  FIG.  11 D ). 
       FIG.  11 E  shows an embodiment of a battery  510  with a first terminal  520  on one end and a second terminal  530  on an opposite end. Terminals  520 ,  530  are generally thin flat members (e.g. blades). 
       FIG.  11 F  shows an embodiment of a battery  610  with terminals  620 ,  630  that are located on the same end of battery  610  and are generally thin flat members bent into a generally L-shaped profile. According to an embodiment, first terminal  620  and second terminal  630  are bent such that the horizontal portions of terminals  620 ,  630  extend toward and beyond the periphery of battery  610 . First terminal  620  and second terminal  630  are configured to have horizontal portions of slightly different lengths such that first terminal  620  on one battery  610  may rest on second terminal  630  of an adjacent battery  610 . 
       FIG.  11 G  shows an embodiment of a battery  710  with a first terminal  720  on one end and a second terminal  730  on an opposite end. Terminals  720 ,  730  are generally thin flat members bent into a generally L-shape profile. According to an embodiment, terminals  720 ,  730  are bent such that the horizontal portions of terminals  720 ,  730  extend in the same direction. According to other embodiments, terminals  720 ,  730  may be bent in opposite directions or may extend at some other angle relative to each other. 
     Referring to  FIG.  12   , a battery  810  is shown according to an embodiment and includes a top portion, or cover  830 , a bottom portion, or container  820 , and a seal portion  860 . According to an embodiment, cover  830  is provided with raised portions or terminals  840 ,  850  that may act as positive and/or negative terminals for battery  810 . Terminals  840 ,  850  may be integrally formed with cover  830  (e.g., not welded) so as to reduce manufacturing costs and the number of component parts associated with battery  810 . 
     As shown in  FIG.  12   , seal  860  may be applied around the upper portion of container  820 . According to an embodiment, seal  860  comprises a polymer material such as a polyethylene, etc. According to various embodiments, other materials may be used to make seal  860 . Seal  860  may be provided in a tape or strip form and wrapped around container  820  as shown in  FIG.  12    and, in some instances, held in place with an adhesive (e.g., either as an integral part of seal  860  or as a separately provided component). 
     According to an embodiment, in order to attach cover  830  to container  820 , cover  830  is first heated to expand the inside diameter of cover  830 . While in the expanded condition, cover  830  is fitted over container  820  and seal  860  such that the heat from cover  830  at least partially melts seal  860 , thereby helping to seal cover  830  to container  820 . As cover  830  is allowed to cool, cover  830  contracts while positioned over container  820 , forming a tight, sealed joint between cover  830  and container  820 . 
     According to an embodiment, the inside diameter of cover  830  is approximately the same as the outside diameter of container  820 , thereby providing a secure fit between cover  830  and container  820  after coupling of cover  830  to housing  820 . According to various embodiments, the dimensions of cover  830  and/or container  820  may be varied to provide a more or less snug fit for various applications. Furthermore, seal  860  may be provided on cover  830  rather than container  820 . 
     According to an embodiment, seal  860  is configured to act as a vent for battery  810 . For example, seal  860  may deteriorate (e.g., melt, etc.) as a result of the pressure and/or temperature within battery  810  reaching a predetermined level, thereby permitting pressurized gases or other fluids to escape from within battery  810 . This provides for a method of venting battery  810  that avoids the expense and time of manufacturing and assembling separate components to provide for venting of battery  810 . 
     As shown in  FIG.  12   , battery  810  is provided as a generally cylindrical battery having a generally circular cross-section. Terminals  840 ,  850  shown in  FIG.  12    are integrally formed with cover  830 . Cover  830  may be either conductively coupled to or insulated from container  820 . According to various other embodiments, battery  810  may take other shapes and forms, and terminals  840 ,  850  may be provided as integrally formed terminals in a variety of locations. 
     Referring now to  FIG.  13   , a battery  910  is shown according to an embodiment. As shown in  FIG.  13   , battery  910  includes a cover  930  and a container  920 . According to an embodiment, container  920  includes terminals  940 ,  950  that may be integrally formed with container  920 . A seal  960  that may be similar to seal  860  discussed with respect to  FIG.  12    is provided around the lower portion of container  920  to seal cover  930  to container  920  in a manner similar to that discussed with respect to  FIG.  12   . 
     According to an embodiment, battery  910  is similar to battery  810  and may be manufactured and assembled in a similar manner except that terminals  940 ,  950  are integrally formed with container  920  (rather than with cover  930 ), and cover  930  is intended to engage the bottom portion of container  920  (rather than the top portion as shown in  FIG.  12   ). Furthermore, battery  910  is provided with an elongated (e.g., oval, etc.) cross-section, rather than the generally circular cross-section of battery  810 . According to various other embodiments, other modifications may be made to batteries  810 ,  910  in order to accommodate various specific applications. For example, seals  860 ,  960  may be reinforced by other methods of sealing (e.g., laser welding, sonic welding, adhesives, etc.). 
     Referring now to  FIG.  14   , a method of connecting the terminals  1012 ,  1014  of adjacent cells  1010  is shown according to an embodiment. Each of the cells  1010  are electrically coupled to one or more other cells  1010  or other components of the battery system  116  (shown, e.g., in  FIG.  2 A ) using connectors provided in the form of bus bars  1016  or similar elements. For example,  FIG.  14    shows two cells  1010  coupled together with a bus bar  1016  according to an embodiment. A portion of the bus bar  1016  is shown as a broken view to show the interface between the bus bar  1016  and the terminal  1012 . The bus bar  1016  is a metallic member (e.g., copper, copper alloy, aluminum, aluminum alloy, etc.) that couples the negative terminal  1014  of a first cell  1010  to the positive terminal  1012  of a second cell  1010 . The bus bar  1016  includes a first end  1018  that is coupled to the negative terminal  1014  of the first cell  1010  (e.g., by an interference fit, by welding, etc.) and a second end  1020  that is coupled to the positive terminal  1012  of a second cell  1010  (e.g., by an interference fit, by welding etc.). 
     The first end  1018  and the second end  1020  of the bus bar  1016  each include a projection  1022  (e.g., protruding ridge, lip, flange, extension, etc.) that is configured to substantially surround the terminal  1012 ,  1014  of a cell  1010 . The projection  1022  may be cast or formed by a mechanical process such as a stamping operation, a punching operation, or an extrusion operation. The mechanical process causes the projection  1022  to extend outward from the top surface  1024  of the bus bar  1016 . The projection  1022  forms a generally vertical wall  1026  that defines an aperture  1028  that is configured to receive the terminal  1012 ,  1014  of the projection  1022 . 
     According to an embodiment, the aperture  1028  has a diameter that is smaller than the diameter of the terminal  1012 ,  1014  so that the bus bar  1016  is coupled to the cell  1010  with an interference fit when the terminal  1012 ,  1014  is received by the aperture  1028 . The bus bar  1016  is assembled with the cells  1010  by first heating the bus bar  1016  (e.g., by induction heating, by an oven, by a flame or heating element, etc.). According to an embodiment, the heating of the bus bar  1016  occurs as part of an assembly line process where the bus bars  1016  being are heated (e.g., in an oven) in the assembly line and directly assembled with the cells  1010 . 
     According to an embodiment, the bus bar  1016  is heated to a temperature sufficient to expand the material of the bus bar  1016 , widening the aperture  1028  formed by the projection  1022  and allowing the terminal  1012 ,  1014  to be received by the aperture  1028  in the bus bar  1016 . According to various embodiments, these temperatures may vary depending on the material properties of the bus bars  1016  (e.g., coefficient of thermal expansion). As the bus bar  1016  cools, the diameter of the aperture  1028  shrinks, forming an interference fit with the terminal  1012 ,  1016 . An insulator  1132  (e.g., as shown in  FIG.  15   ) may be provided below the bus bar  1016  and around the terminal  1012 ,  1014  to reduce the chance of inadvertent contact between the bus bar  1016  and the lid or cover  1034  of the cell  1010 . 
     The bus bar  1016  may be further coupled to the cell  1010  with a welding operation such as an ultrasonic welding operation, a laser welding operation, or a resistance welding operation. According to another embodiment, the bus bar  1016  may be welded to the terminals  1012 ,  1014  of the cells  1010  instead of being provided with an interference fit and welded to the terminals  1012 ,  1014  of the cells  1010 . According to another embodiment, the bus bar  1016  may be press fit to the terminals  1012 ,  1014  of the cells  1010  instead of being welded to the terminals  1012 ,  1014  of the cells  1010 . 
       FIGS.  15 - 16    show a bus bar  1116  according to another embodiment coupled to a terminal  1112  of a cell  1110 . A portion of the bus bar  1116  is shown as a broken view to show the interface between the bus bar  1116  and the terminal  1112 . The bus bar  1116  is a metallic member (e.g., copper, copper alloy, aluminum, aluminum alloy, etc.) that couples a first cell  1110  to a second cell (e.g., as shown in  FIG.  16   ). The bus bar  1116  includes a first end  1118  that is coupled to a terminal  1112  of the first cell  1110  (e.g., by an interference fit, by welding, etc.) and a second end  1120  that is coupled to the housing  1136  of the second cell  1110  (e.g., by a press fit, by an interference fit, by welding, etc.). The first end  1118  of the bus bar  1116  shown in  FIG.  15    is similar to the first end  1018  of the bus bar  1016  shown in  FIG.  14   . However, the second end  1120  of the bus bar  1116  shown in  FIG.  15    is configured to be coupled to the housing  1136  of a second, adjacent cell  1110  and to act as a cover for the second cell. 
     The first end  1118  of the bus bar  1116  includes a projection  1122  (e.g., protruding ridge, lip, flange, extension, etc.) that is configured to substantially surround the terminal  1112  of a first cell  1110 . The projection  1122  may be cast or may be formed by a mechanical process such as a stamping operation, a punching operation, or an extrusion operation. The mechanical process causes the projection  1122  to extend outward from a top surface  1124  of the bus bar  1116 . The projection  1122  forms a generally vertical wall  1126  that defines an aperture  1128  that is configured to receive the terminal  1112  of the cell  1010 . In other words, the terminal  1112  is received in the aperture  1128  defined by the projection  1122  of the bus bar  1116  such that contact is made between the terminal  1112  and an inner surface  1130  of the projection  1122 . 
       FIG.  16    shows a portion of a battery module including two cells  1110  coupled together with the bus bar  1116  of  FIG.  15   . The cells  1110  are generally cylindrical bodies with a top or first surface  1134  having a terminal  1112  (e.g., a negative terminal, a positive terminal) that extends generally upward from the top surface  1134 . The terminal  1112  is electrically coupled to a first electrode (not shown) inside the housing  1136  of the cell  1110  (e.g., a negative electrode, a positive electrode). However, the terminal  1112  is electrically insulated from the housing  1136  itself (e.g., by an insulator  1132 ). The housing  1136  of the cell  1110 , including the top surface  1134  of the cell  1110 , is electrically coupled to a second electrode (not shown) inside the housing  1136  of the cell  1010  (e.g., a positive electrode, a negative electrode). 
     The bus bar  1116  is coupled to the cells  1110  by first coupling the second end  1120  of the bus bar  1116  to the top surface  1134  of the of the second cell  1110 . According to an embodiment, the second end  1120  of the bus bar  1116  is press fit into the top of the housing  1136  of the second cell  1110  and then welded (e.g., ultrasonic, laser, resistance, etc.) to form a cover for the cell  1110  (i.e., the cover includes an extension or flange that acts as a bus bar or terminal for coupling to an adjacent cell). According to another embodiment, the second end  1120  of the bus bar  1116  is larger than the diameter of the top of the second cell  1110  and is coupled to the top of the second cell  1110  with an interference fit. The second end  1120  of the bus bar  1116  is shrunk (e.g., reduced in size, made smaller, etc.) by a cooling process (e.g., using liquid nitrogen). The second end  1120  of the bus bar  1116  is then placed into the open end of the top of the second cell  1110  and allowed to return to room temperature. The second end  1120  of the bus bar  1116  may then be further coupled to the cell  1110  by a welding operation such as an ultrasonic welding operation, a laser welding operation, or a resistance welding operation. 
     The first end  1118  of the bus bar  1116  is then coupled to the terminal  1112  of the first cell  1110 . According to an embodiment, the first end  1118  of the bus bar  1116  is welded (e.g., ultrasonic, laser, resistance, etc.) to the terminal  1112  of the first cell  1110 . According to another embodiment, the first end  1118  of the bus bar  1116  is press fit to the terminal  1112  of the first cell  1110 . According to another embodiment, the aperture  1128  in the first end  1118  of the bus bar  1116  has a diameter that is smaller than the diameter of the terminal  1112  so that the first end  1118  of the bus bar  1116  is coupled to the terminal  1112  of the first cell  1110  with an interference fit. The first end  1118  of the bus bar  1116  is heated (e.g., by placing the first end  1118  near a heating element or a flame). Heating the first end  1118  of the bus bar  1116  expands the metal, widening the aperture  1128  formed by the projection  1122  and allowing the terminal  1112  to be received in the aperture  1128  in the first end  1118  of the bus bar  1116 . As the bus bar  1116  cools, the diameter of the aperture  1128  shrinks, forming an interference fit with the terminal  1112 . An insulator  1132  (e.g., as shown in  FIG.  16   ) may be provided below the bus bar  1116  and around the terminal  1112  to reduce the chance of inadvertent contact between the bus bar  1116  and the housing  1136  of the cell  1010 . The bus bar  1116  may then be further coupled to the terminal  1112  of the cell  1010  with a welding operation such as an ultrasonic welding operation, a laser welding operation, or a resistance welding operation. 
     Referring now to  FIGS.  17 - 18   , a cell can or housing  1212  (e.g., a container, casing, etc.) for an electrochemical cell  1210  is shown according to an embodiment. The housing  1212  is configured to receive or house a cell element (e.g., a wound cylindrical cell element) that is not shown. According to an embodiment, the housing  1212  comprises a three-piece structure, comprising a main body  1214  (that may, e.g., be made from an aluminum tube or tubing), a first cover or bottom  1216 , and a second cover or lid  1218  that includes a flange (e.g., a tab, flap, projection, extension, protrusion, projection, lip, overhang, protuberance, etc.) that acts as a bus bar or terminal for coupling the cell  1210  to a terminal of an adjacent cell. 
     As shown in  FIG.  18   , the three-piece housing  1212  provides for a flexible design that may be varied (e.g., in length) to provide for various sizes and capacities of cell elements. For example, a different length main body  1214  may be used with the same bottom  1216  and lid  1218 . Additionally, internal connections (e.g., current collectors, etc.) may be changed for different applications without affecting the design of the external interface (e.g., the lid  1218 , the bus bars  1226 , etc.) of the module that the cells  1210  are provided in. Furthermore, this type of separate component design allows for lower cost tooling for development and higher efficiencies in economies of scale in that the same design for the bottom  1216  and the lid  1218  may be used interchangeably with different lengths of the main body  1214 . 
     According to an embodiment, the separate components (i.e., the main body  1214 , bottom  1216 , and lid  1218 ) are easier to clean and handle than previous designs. For example, the main body  1214 , bottom  1216 , and lid  1218  may be cleaned separately and then assembled together. Previous designs having the bottom or the lid integral with the main body made it difficult to clean the inside of the main body and/or the bottom or lid. Having separate components allows for full accessibility to the components of the housing  1212 . 
     Referring now to  FIG.  18   , the bottom  1216  may have an integral vent feature  1220  according to an embodiment. The vent feature  1220  may be configured to separate or deploy from the bottom  1216  if the pressure inside the housing  1212  reaches a predetermined amount. Various sized vents  1220  may be used with the bottom  1216 , allowing different internal pressures to be obtained depending on the design (e.g., size) of the vent  1220  used. Additionally, the various sized vents  1220  may be interchanged with different sized housings  1212 , dependent upon the needs of the application. According to an embodiment, the bottom  1216  is coupled (e.g., by a welding process, such as laser welding) to a lower portion of the housing  1212 . 
     Referring to  FIGS.  19 - 20   , the cover  1218  or lid for the housing  1212  is shown according to an embodiment. The lid  1218  includes a first terminal  1222  (e.g., a positive terminal) that may be provided, for example, in the center of the lid  1218 . The first terminal  1222  is insulated from the lid  1218  by the use of an insulating material or insulating device shown as an insulator  1224 . The first terminal  1222  may be coupled to an electrode (e.g., a positive electrode) of the cell element (not shown) with a current collector (not shown). According to an embodiment, the lid  1218  is coupled (e.g., by welding process, such as laser welding) to an upper portion of the housing  1212 . 
     Still referring to  FIGS.  19 - 20   , the lid  1218  also comprises a member shown as a flange (e.g., a tab, flap, projection, extension, protrusion, projection, lip, overhang, protuberance, etc.) that may act as a terminal or bus bar  1226  for the cell  1210 . According to an embodiment, the bus bar  1226  is integral with the lid  1218  (i.e., the bus bar  1226  and lid  1218  are a single unitary body). Having the bus bar  1226  integral with the lid  1218  reduces the overall component count of the system. Additionally, the number of fasteners (not shown) used (e.g., to couple the bus bars  1226  to the terminals  1222 ) is reduced. Furthermore, the overall system cost may be reduced by eliminating or reducing the amount of copper used by having integral bus bars  1226 . 
     As shown in  FIGS.  19 - 20   , the bus bar  1226  extends out and away from the lid  1218 . According to an embodiment, the bus bar  1226  is at a height that is different (i.e., higher) than the height of the lid  1218 , allowing the bus bar  1226  to be placed over (i.e., on top of) a terminal  1222  of an adjacent cell  1210 . The bus bar  1226  is configured with an aperture  1228  at an end of the of the bus bar  1226 . According to an embodiment, the aperture  1228  is configured to allow a fastener (not shown) to be placed through the aperture  1228  in order to couple the bus bar  1226  to a terminal  1222  of an adjacent cell  1210 . 
     According to another embodiment, the lid  1218  may also comprise an aperture or hole shown as fill hole  1230 . Fill hole  1230  is configured to allow a substance (e.g., electrolyte) to be placed in the cell  1210  after the cell  1210  is assembled. According to another embodiment, the lid may also comprise an aperture or hole  1234  (e.g., as shown in  FIG.  20   ) configured to receive the first terminal  1222  and insulator  1224 . 
     According to another embodiment, the bus bar  1226  may function as a second terminal  1232  (e.g., a negative terminal) of the cell  1210  due to the fact that the bus bar  1226  may be electrically connected to an electrode (e.g., a negative electrode) of the cell element (not shown). The bus bar  1226 , being integral with the lid  1218 , may be connected to the electrode by the lid  1218  being electrically connected to the main body  1214  of the housing  1212 . The main body  1214  of the housing  1212  is electrically connected to the bottom  1216  of the housing  1212 , which in turn is then electrically connected to the electrode of the cell element, completing the connection from the bus bar  1226  to the electrode. 
     Referring now to  FIGS.  21 - 24   , a battery module  1300  utilizing cells  1310  having lids  1312  with integral terminals or bus bars  1314  is shown according to an embodiment. The battery module  1300  may be electrically coupled with other battery modules  1300  to form a battery system (not shown) or may be used independently to form its own battery system. The battery system may include other features (not shown) that are responsible for monitoring and controlling the electrical performance of the system, managing the thermal behavior of the system, containment and/or routing of effluent (e.g., gases that may be vented from a cell  1310 ), and other aspects of the battery module  1300  or battery system. 
     As shown in  FIG.  21   , the battery module  1300  includes a plurality of electrochemical cells  1310  each having a flange (e.g., a tab, flap, projection, extension, protrusion, projection, lip, overhang, protuberance, etc.) shown as an integral terminal or bus bar  1314  formed in the lid  1312  of the cell  1310 , a first structure or upper tray  1316 , and a second structure or the lower tray  1318 . The plurality of cells  1310  are provided in between the upper tray  1316  and the lower tray  1318 . Although illustrated in  FIG.  21    as having a particular number of electrochemical cells  1310 , it should be noted that according to other embodiments, a different number and/or arrangement of electrochemical cells  1310  may be used depending on any of a variety of considerations (e.g., the desired power for the battery module  1300 , the available space within which the battery module  1300  is designed to fit, etc.). 
     According to an embodiment, the upper tray  1316  comprises features  1320  (e.g., raised portions, cutouts, channels, spaces, molded areas, etc.) that receive the integral bus bars  1314  of the individual cells  1310  to properly orientate or align the cells  1310  (and the integral bus bars  1314 ) so that the bus bars  1314  are properly aligned to be connected to an adjacent cell  1310 . The upper tray  1316  also comprises a feature shown as a wall  1322  (as shown, e.g., in  FIG.  24   ) that partially surrounds the upper portion of the cell  1310  to aid in properly locating the cell  1310 . It should be noted that the bus bars  1314  used in connection with the upper tray  1316  need not be integral with the lid  1312  (i.e., the upper tray  1316  will still be able to properly align and orientate cells  1310  having non-integral bus bars  1314 ). 
     According to another embodiment, the upper tray  1316  also comprises openings or apertures  1324  that expose a portion of the bus bar  1314  (e.g., the end of the bus bar  1314  having an aperture  1326 ) to be coupled (e.g., with a fastener, by welding, etc.) to a terminal  1328  of an adjacent cell  1310 . According to an embodiment, the terminal  1328  of the adjacent cell  1310  is threaded (e.g., to receive a fastener  1329 , as shown in  FIG.  22   ). According to another embodiment, the terminal  1328  of the adjacent cell  1310  may be flat so that the terminal  1328  may be welded to the bus bar  1314 . The upper tray  1316  may be made of a polymer (e.g., polypropylene, polyethylene, etc.) or any other suitable material (e.g., insulative material). 
     Still referring to  FIG.  21   , the battery module  1300  is shown to include a seal  1330  provided along an upper surface of the lower tray  1318  in order to seal a chamber (not shown) located inside the lower tray  1318 . According to an embodiment, the seal  1330  is configured to seal the gap between the lower portion of the cells  1310  and the lower tray  1318  (when the cells  1310  are placed in the lower tray  1318 ). According to an embodiment, the seal  1330  may be constructed from silicone (e.g., molded silicone) or other appropriate material. 
     According to an embodiment, the seal  1330  is configured to aid in containing any gases that are vented from the cells  1310  into the chamber. For example, gases may be vented from the cells  1310  via a vent device or vent feature  1334  located at the lower end of each of the cells  1310  (shown, e.g., in  FIGS.  23 - 24   ). According to another embodiment, an opening or outlet  1336  (e.g., as shown in  FIG.  21   ) may be provided in fluid connection with the chamber. The outlet  1336  may be used to direct gases from the chamber (after having been vented from the cells  1310 ) to outside the battery module  1300  (e.g., outside the vehicle). 
     Referring now to  FIG.  22   , the battery module  1300  is shown with the upper tray  1316  removed. As can be seen in  FIG.  22   , the bus bars  1314  of the cells  1310  are properly oriented so that they are ready for connection to a terminal  1328  of an adjacent cell  1310  (or for connection to another module  1300  or other component of the battery system). According to another embodiment, the battery module  1300  may also include an aperture or hole shown as fill hole  1332  in the lid  1312  of the cell  1310 . The fill hole  1332  allows a substance (e.g., an electrolyte) to enter the cell  1310 . 
     As shown in  FIGS.  23 - 28   , the upper tray  1316  may be used as an assembly tool or fixture according to an embodiment. As can be seen in  FIGS.  23 - 24   , the cells  1310  having the integral bus bars  1314  are provided in the upper tray  1316  (which is provided upside down). The alignment features  1320  (shown as depressions in  FIGS.  24 , and  27 - 28   ) provided in the upper tray  1316  provide for an assembly/fixturing tool for properly aligning and orientating the individual cells  1310  into place when assembling the module  1300 . Utilizing the upper tray  1316  as an assembly tool saves time, energy, and money in assembling the battery module  1300 . As noted above, the bus bars  1314  used in connection with the upper tray  1316  need not be integral with the lid  1312  (i.e., the upper tray  1316  will still be able to properly align and orientate cells  1310  having non-integral bus bars  1314 ). 
     The cells  1310  (having either an integral bus bar  1314  or a separate bus bar coupled to the lid  1312 ) are provided upside down into the upper tray  1316  (i.e., the end of the cell  1310  having the lid  1312  and bus bar  1314  are placed into the upper tray  1316 ). The bus bar  1314  of each individual cell  1310  will be aligned for proper coupling with the terminal  1328  of another cell  1310  (or to other components of the battery module  1300  or battery system). Additionally, the wall features  1322  of the upper tray  1316  may aid in properly locating the individual cells  1310 . 
     Once the cells  1310  are properly located in the upper tray  1316 , the bottom tray  1318  is assembled to the cells  1310  (again, upside down). The bottom tray  1318  may have a seal  1330  provided on it to seal the lower end of the cells  1310  (as shown in  FIG.  21   ). The battery module  1300  is then turned right side up where the bus bars  1314  are then coupled to their respective terminal  1328  (e.g., by a fastener, by welding, etc.). 
     As noted above, different embodiments of the battery module  1300  may include different numbers or arrangements of the cells  1310  disposed therein. In some embodiments, the cells  1310  may be arranged in a manner that minimizes the space taken up by the cylindrical cells  1310 . To accomplish this, the cells  1310  may be arranged in two or more rows, as shown in  FIG.  22    for example, and the cells  1310  in one row may be offset from the cells  1310  in an adjacent row so that more cells  1310  can be packaged into a closer space. The bus bars  1314  may be sized appropriately for this type of arrangement. 
     Although the embodiments of  FIGS.  21 - 24    involve an arrangement of twelve cylindrical battery cells  1310 , other numbers of cells  1310  may be utilized in different embodiments. For example, it may be desirable for the battery module  1300  to include thirteen cells  1310  instead of twelve, as shown in  FIG.  29   , to reach a desired power output for the battery module  1300 . Specifically, the nominal voltage of each cell  1310  may be approximately 3.65V for NMC and NCA chemistries, although the voltages may vary with state of charge and other parameters. Thirteen of these cells  1310  would yield a nominal voltage of approximately 48V. In other embodiments, different chemistries of the cells  1310  could have different voltages and, thus, may result in a different number of cells  1310  in the battery module  1300 . For example, iron phosphate cells, which may have less variation in voltage than the NMC/NCA cells, have a nominal voltage of approximately 3.2V, and fifteen of these cells would yield a nominal voltage of approximately 48V. 
     As illustrated in  FIG.  29   , the cells  1310  are arranged into three rows  1350 ,  1352 , and  1354 . The first row  1350  includes four cells  1310 , the second row  1352  includes five cells  1310 , and the third row  1354  includes four cells  1310 . In other embodiments, however, the five cells  1310  may be located in the first row  1350  or the third row  1354 . The second row  1352  is disposed between and adjacent to the first and third rows  1350  and  1354 . Again, the cells  1310  in each row are staggered relative to the cells  1310  in adjacent rows. That is, the cells  1310  in the second row  1352  are staggered relative to the cells  1310  in both the first row  1350  and the third row  1354 , allowing for tighter packing of the cells  1310  within the battery module  1300 . 
     As discussed above, the cells  1310  may be electrically coupled to each other (e.g., in series) to provide a desired voltage output through terminal connections (not shown) of the battery module  1300 . The battery module  1300  includes two end cells  1310 A and  1310 B, one at each end of the electrically coupled string of battery cells  1310 . These end cells  1310 A and  1310 B may be used to couple the rows of cells  1310  to the positive and negative terminal connections of the battery module  1300 . In some embodiments, the terminal connections to which the end cells  1310 A and  1310 B are coupled may include a connection between the cells  1310  in the illustrated battery module  1300  and another group of battery cells disposed in an adjacent battery module of a larger battery system. 
     Between these two end cells  1310 A and  1310 B are a number (e.g., eleven) of intermediate cells  1310  that help to increase the voltage difference available through the terminal connections of the battery module  1300 . In some embodiments (e.g.,  FIGS.  30  and  31   ), the end cells  1310 A and  1310 B may be disposed one at each end of the same row (e.g., second row  1352 ) of cells  1310 . In embodiments where the battery module  1300  functions as a standalone module, this alignment of the end cells  1310 A and  1310 B may allow for simpler assembly of the battery module  1300 , since symmetrical terminal conductors can transfer the power from the cells  1310  to external battery terminals. In embodiments where the battery module  1300  is coupled to other battery modules, the aligned end cells  1310 A and  1310 B may facilitate relatively easy connection of the battery modules, since the end cells  1310 A and  1310 B of all the modules are aligned with each other. In other embodiments (e.g.,  FIG.  29   ), however, the battery module  1300  may include one end cell  1310 B in the second row  1352  and the other end cell  1310 A in either the first row  1350  or the third row  1354 . In this case, the battery module  1300  may be equipped with asymmetrical terminal conductors for transmitting the power to terminals of the battery module  1300 , or to the cells  1310  in an adjacent battery module  1300 . 
     In the illustrated embodiment of  FIG.  29   , the cells  1310  are electrically coupled via the bus bars  1314  across the three rows  1350 ,  1352 , and  1354  in a zigzag pattern. More specifically, the cells  1310  are oriented such that the intermediate cells  1310  are connected in a pattern that snakes back and forth between the cells  1310  in each of the different rows while traversing along a length of the rows. Each of the intermediate cells  1310  located in the first row  1350  are coupled (via bus bars  1314 ) between an adjacent cell  1310  in the first row  1350  and a cell  1310  in the second row  1352 . Each intermediate cell  1310  located in the second row  1352  is coupled between a cell  1310  in the first row  1350  and a cell in the third row  1354 . Further, each intermediate cell  1310  located in the third row  1354  is coupled between an adjacent cell  1310  in the third row  1354  and a cell  1310  in the second row  1352 . Other arrangements of battery modules  1300  that utilize multiple rows of cells  1310  coupled together may feature similar zigzag patterns of bus bar connections between the cells  1310 , in other embodiments. 
     The three row zigzag pattern of connecting the cells  1310  via the bus bars  1314  in  FIG.  29    is also used in the embodiment of the battery module  1300  shown in  FIG.  22   . This embodiment has twelve cells  1310  coupled together, four cells  1310  in each of three separate rows. Thus, presently disclosed battery modules  1300  may include cells  1310  that are coupled together via flanged bus bars  1314  in the above described pattern, regardless of whether the total number of battery cells  1310  is twelve, thirteen, or some other number. 
     Other zigzag patterns may be employed in three-row arrangements of the battery cells  1310 . For example,  FIG.  30    illustrates one such arrangement of cells  1310  that follows a similar zigzag pattern as the embodiment of  FIG.  29   , with a slight change at the negative end (e.g., toward end cell  1310 B). This arrangement of the cells  1310  positions the end cell  1310 B at the negative end of the battery module  1300  into alignment with the end cell  1310 A at the positive end. Both of these end cells  1310 A and  1310 B are in the third row  1354 , so that symmetrical terminal conductors can couple the battery cells  1310  with external battery terminals or adjacent battery modules. 
     In still further embodiments, other variations of zigzag patterns may be used for electrically coupling the offset cells  1310  in multiple rows. As an example of this,  FIG.  31    shows another embodiment of the battery module  1300  that includes thirteen cells  1310  for providing a desired voltage drop across the battery module  1300 . The illustrated embodiment includes a first row  1360  of seven cells  1310  and a second row  1362  of six cells  1310 . As discussed above, the cells  1310  in the first row  1360  are offset from the cells  1310  in the second row  1362  to allow a relatively efficient use of space for packaging the cells  1310  within the battery module  1300 . 
     In the illustrated embodiment of  FIG.  31   , the cells  1310  are coupled together via the bus bars  1314  in a different zigzag pattern than the pattern described above with reference to  FIG.  29   . Specifically, the illustrated zigzag pattern alternates between battery cells  1310  disposed in the first row  1360  and battery cells  1310  disposed in the second row  1362 . This arrangement may provide an adequate amount of space between the different bus bars  1314  that are used to connect the cells  1310 . A similar zigzag pattern may be used in embodiments of the battery module  1300  that include twelve cells  1310  coupled together and disposed in two rows. It should be noted that, in some embodiments, the bus bar  1314  extending from the end cell  1310 A may be oriented with the row  1360 , as indicated by reference number  1363 . This aligns the bus bar  1314  extending from the end cell  1310 A at the positive end of the battery module with the end cell  1310 B at the negative end. As discussed above, this alignment may enable relatively easy and symmetrical assembly of the battery module  1300  or group of battery modules  1300 . 
     It should be noted that the arrangements of cells  1310  described above feature the cells  1310  oriented such that the bus bars  1314  are positioned at relative angles to each other. These angles are small enough that a zigzag pattern can be used for connecting the cells  1310 , and the angles are large enough that the bus bars  1314  do not intersect or touch one another. In the illustrated embodiments of  FIGS.  22 ,  29 ,  30   , and  31 , the cells  1310  are oriented such that the bus bars  1314  corresponding to each pair of adjacent cells  1310  that are coupled together are offset by an angle of either approximately 60 degrees or approximately 120 degrees. The term approximately in this instance means within ten degrees.  FIGS.  29  and  30    illustrate pairs of adjacent bus bars  1314  that are oriented with an offset angle  1364  of approximately 60 degrees from each other. In addition, other pairs of adjacent bus bars  1314  in these embodiments are oriented with an offset angle  1366  of approximately 120 degrees from each other. In the embodiment of  FIG.  31   , however, every adjacent pair of bus bars  1314  is oriented with an offset angle  1368  of approximately 60 degrees from each other. In the illustrated embodiments, there are no two adjacent bus bars  1314  that are entirely aligned with each other. 
     It should be noted that certain features disclosed with reference to  FIG.  21    may be present in battery modules  1300  having any of the above described cell arrangements. That is, the battery module embodiments illustrated in  FIGS.  29  and  30    may also include the upper tray  1316  with cell alignment features  1320 , and the lower tray  1318  with the chamber and the seal  1330 . In addition, other embodiments of battery modules  1300 , which may have different numbers of cells  1310  or rows of cells  1310  coupled together, can be oriented according to the zigzag patterns described above, and may include the tray  1316  and/or the chamber as well. 
     According to one embodiment, a battery module includes a plurality of electrochemical cells provided in between a bottom tray and an upper tray. The electrochemical cells may include a housing having a tubular main body, a bottom, and a lid. The bottom may include a vent feature to allow venting of gases and/or effluent from inside the housing. The lid may include a first terminal that is insulated from the lid and a bus bar that is integral to the lid. The integral bus bar may serve as a second terminal of the cell. The battery module may also include a seal provided between the lower end of the cell and the lower tray to seal a chamber configured to receive vented gases from the cells. The upper tray may include features and/or cutouts to help properly align and orientate the cells having integral bus bars. 
     According to another embodiment, the battery module includes a plurality of electrochemical cells provided in between a first structure and a second structure. Each of the electrochemical cells includes a feature extending from a top of the electrochemical cells, the feature configured to electrically couple the electrochemical cell to a terminal of an adjacent electrochemical cell or other component of the battery module. The first structure includes features to properly orientate each of the electrochemical cells. 
     According to another embodiment, a method of assembling a battery module includes providing a plurality of electrochemical cells in a first structure. Each of the plurality of electrochemical cells has a lid having an integral bus bar. The first structure has features to properly orientate the integral bus bars of each of the plurality of electrochemical cells. The method further includes providing a second structure over the ends of the electrochemical cells. 
     One advantageous feature of providing terminals that are integrally formed with a cover, lid, or container for a battery or cell is that the need to separately manufacture and couple the terminal to the cover, lid, or container is eliminated. In this manner, labor and manufacturing costs may be reduced as compared to other cells in which terminals are separately manufactured from the lid, cover, or container (e.g., by eliminating steps in the manufacturing operation). Additionally, providing terminals that are integrally formed reduces the opportunity for failure modes to take effect (e.g., because the terminal is not welded to the cover or container, there is not a weld point which may be a point of electrical shorting or failure) 
     According to another embodiment, a battery module includes a plurality of electrochemical cells provided in at least two rows such that the cells in each row are offset from the cells in adjacent rows. The plurality of cells are electrically coupled to each other to output a voltage drop across two terminal connections of the battery module. Some embodiments may include an arrangement of twelve or thirteen total cells disposed in the rows. In some embodiments, the battery module includes two rows of cells that are connected in a zigzag pattern. In other embodiments, the battery module includes three rows of cells that are connected via bus bars or integral terminals extending from one cell to the next. More specifically, battery cells located in a first row may be coupled between an adjacent cell in the first row and a cell in the second row. Battery cells located in the second row may be coupled between a cell in the first row and a cell in the third row, and battery cells located in the third row may be coupled between a cell in the second row and an adjacent cell in the third row. The offset angles between adjacent bus bar terminals in each of the disclosed cell arrangements may enable a relatively space efficient packaging of the cells within the battery module. 
     While only certain features and embodiments of the disclosed embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the disclosed embodiments, or those unrelated to enabling the claimed embodiments). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.