Battery pack with a pressure management system

Abstract

A battery pack includes a battery pack housing sealed and filled with a dielectric fluid. Additionally, the battery pack includes a battery module disposed in the battery pack housing and a vent block disposed on a lid and in communication with an interior space of the battery pack housing. The vent block is configured to allow the battery pack to accommodate volume changes of the dielectric fluid within the battery pack housing.

Description

Technical Field

[0001] Battery packs power a variety of technologies ranging from portable electronic devices to renewable energy systems and environmentally friendly vehicles. For example, hybrid electric vehicles use a battery pack and an electric motor in combination with an internal combustion engine to improve fuel efficiency. A battery pack can be formed from multiple battery modules, where each battery module includes a plurality of electrochemical cells. Within a battery module, the cells can be electrically connected in series or in parallel. Similarly, the battery modules can be electrically connected in series or in parallel within the battery pack. Background Art

[0002] To meet the space requirements of various applications and installation environments, different battery types have emerged. The most common types in vehicles are cylindrical batteries, prismatic batteries, and pouch batteries. For example, cylindrical batteries are widely used due to their ease of manufacturing and stability. However, due to their curved shape, the packaging efficiency of cylindrical batteries in a battery module may be lower than that of some other types of batteries. In addition, due to the need for electrical connections at each end of the cylindrical battery, there are additional challenges in providing a battery module with effective space management. Moreover, when the current collectors are arranged at each opposite end of the battery, battery cooling via immersion in a liquid coolant is also challenging.

[0003] In some conventional battery modules, a battery support structure is provided to hold the batteries in a desired configuration and provide battery cooling. However, such a battery support structure may be complex and have sufficient volume to further reduce the packaging efficiency of the battery module. There is a need for a power generation and storage device that is simple to use and manufacture, has a stable and orderly arrangement of cylindrical batteries within the battery module, and occupies a minimum space volume within the battery module while providing battery cooling. Summary of the Invention

[0004] In some aspects, the battery pack includes a battery pack housing. The battery pack housing includes a container and a lid, the lid closing an open end of the container and being joined to the open end of the container via a fluid-impermeable seal. The battery pack includes a battery module disposed in the battery pack housing. The battery module includes a module housing and electrochemical cells disposed in the module housing. Additionally, the battery pack includes a vent block disposed on the lid. The vent block includes an internal space and a first hole extending between an exterior of the vent block and the internal space. The first hole is in fluid communication with an internal space of the battery pack housing. The vent block includes a second hole extending between an exterior of the vent block and the internal space. The second hole includes a first vent hole that is normally closed and opens at a predetermined fluid pressure. The vent block includes a third hole extending between an exterior of the vent block and the internal space. The third hole includes a second vent hole that is fluid-impermeable but air-permeable. The battery pack housing is filled with a dielectric fluid, and the vent block allows the battery pack to accommodate volume changes of the dielectric fluid within the battery pack housing.

[0005] In some embodiments, the battery pack includes a fitting having a first end, a second end opposite the first end, and a longitudinal fluid passage extending between the first end and the second end. The vent block is disposed on an outer surface of the lid. The first end of the main fitting projects through the lid and engages the first hole of the vent block, whereby the vent block is configured to be securable to the lid. Additionally, the longitudinal fluid passage provides fluid communication between the internal space of the vent block and the interior of the battery pack housing.

[0006] In some embodiments, the second vent hole includes a polytetrafluoroethylene membrane.

[0007] In some embodiments, the first vent hole includes an umbrella valve.

[0008] In some embodiments, the vent block includes a cap that covers the first vent hole and the second vent hole and is spaced apart from the first vent hole and the second vent hole.

[0009] In some embodiments, the second hole and the third hole intersect.

[0010] In some embodiments, the first hole is perpendicular to the outer surface of the lid, and the second hole and the third hole are perpendicular to the first hole.

[0011] In some embodiments, the main fitting is configured to be securable to the lid.

[0012] In some embodiments, the battery pack includes a pressure compensation device disposed in the battery pack housing. The pressure compensation device includes an internal space. The battery pack includes a fitting connecting the vent block to the pressure compensation device, the fitting including: a first end connected to the first hole; a second end opposite the first end; a sidewall extending between the first end and the second end, the sidewall having an inner surface defining a longitudinal fluid passage extending between the first end and the second end; and a transverse fluid passage extending between an opening in the sidewall and the longitudinal fluid passage. The internal space of the pressure compensation device is in fluid communication with the internal space of the vent block via the transverse fluid passage and the longitudinal fluid passage.

[0013] In some embodiments, the fitting includes: a first flange protruding outward from an outer surface of the sidewall, the first flange disposed between the opening and the first end; and a second flange protruding outward from the outer surface of the sidewall, the second flange disposed between the opening and the second end. A first portion of the fitting extends through a first opening in the pressure compensation device, and a first seal assembly provides a fluid seal between the first opening in the pressure compensation device and the first flange. Additionally, a second portion of the fitting extends through a second opening in the pressure compensation device, and a second seal assembly provides a fluid seal between the second opening in the pressure compensation device and the second flange.

[0014] In some embodiments, the first seal assembly and the second seal assembly include an elastic gasket, a rigid washer, and a nut.

[0015] In some embodiments, the pressure compensation device includes a first wall portion covering a second wall portion, and wherein the fitting extends through openings in the first wall portion and the second wall portion such that: the first end is disposed outside the pressure compensation device on a side of the pressure compensation device corresponding to the first wall portion, and the first end is disposed in the first hole; the second end is disposed outside the pressure compensation device on a side of the pressure compensation device corresponding to the second wall portion; and the opening in the sidewall is disposed in the internal space of the pressure compensation device.

[0016] Each battery module includes a busbar assembly that provides battery terminal interconnection within the battery module. Each busbar assembly includes a substrate and an insulating layer attached to a battery-facing surface of the substrate. The insulating layer is electrically insulating and thermally insulating, and is also flame retardant. In some embodiments, each surface of the insulating layer includes a pressure-sensitive adhesive, whereby the insulating layer is attached to the substrate and the battery ends. The insulating layer can prevent short circuits when the battery expands and contracts within the module. Additionally, the insulating layer is flame retardant, so it can maintain its electrical and thermal isolation properties in the event of battery thermal runaway.

[0017] In a battery module, the positive terminal of each battery is connected to a bus bar assembly via a first electrical connector, and the negative terminal of the battery is connected to another bus bar assembly via a second electrical connector. In some embodiments, the first electrical connector and the second electrical connector are configured such that the current-carrying capacity of the first electrical connector is less than the current-carrying capacity of the second electrical connector. By providing a first electrical connector and a second electrical connector in which the current-carrying capacity of the first electrical connector is less than the current-carrying capacity of the second electrical connector, each battery is electrically connected to the corresponding bus bar assembly such that the electrical connection to the positive terminal of the battery fails before the electrical connection to the negative terminal of the battery, thereby opening the internal circuit of the battery module. The opening of the internal circuit of the battery module 40 can help prevent the unlikely situation where an internal short circuit of the battery may cause a direct short circuit between the batteries of the battery module.

[0018] A battery pack includes a plurality of battery modules, and the battery modules are bundled in a sub-assembly called a cartridge. The cartridges are arranged in a battery pack housing, and the internal space of the battery pack housing is filled with a dielectric, non-flammable, and chemically inert engineering fluid. Although the battery modules may be passively cooled by immersion in the engineering fluid, the battery pack includes a thermal management system in which the engineering fluid is actively driven across the battery surfaces. This is achieved by delivering the fluid to each cartridge, using an inlet plenum assembly to distribute the fluid to the battery modules within the cartridge, using an outlet plenum assembly to collect the fluid that has been heated by the batteries, and removing the heated fluid from the batteries. By providing passive and active cooling of the batteries, battery function is improved and battery durability is increased.

[0019] Since the battery pack is filled with the engineering fluid, the battery modules and the cartridges do not include fluid-sealing features to facilitate active cooling. Thus, the components of the battery modules, cartridges, and thermal management system are simplified relative to the active thermal management systems of some conventional battery packs, and thus manufacturing is easier and less costly.

[0020] Advantageously, the thermal management system can be configured such that the fluid flow rate of the cooling fluid delivered to each battery module can be set individually, thereby allowing an increase in the fluid flow rate in areas where the temperature is detected to be higher than other areas. In this way, the operating temperature of each battery module of the battery pack can be controlled individually, and the overall temperature of the battery pack can be balanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a side view of the battery pack;

[0022] Figure 2 is Figure 1 a perspective view of the battery pack of

[0023] Figure 3 is a perspective view of the cartridge;

[0024] Figure 4 is a perspective view of the cartridge, wherein the fluid inlet plenum assembly and the outlet plenum assembly are omitted to show the battery module disposed within the cartridge;

[0025] Figure 5 is a perspective view of the cartridge housing with the battery module omitted;

[0026] Figure 6 is a perspective view of the battery module;

[0027] Figure 7 is along Figure 6 a cross-sectional view of the battery module as seen along line 7-7 of;

[0028] Figure 8 is an exploded perspective view of the battery module;

[0029] Figure 9 is a partially exploded perspective view of the electrochemical cell;

[0030] Figure 10 is a schematic view of the arrangement of the cells in the battery module;

[0031] Figure 11 is a side view of the cell array within the battery module, showing the arrangement of the cells in the quadrants;

[0032] Figure 12 is a perspective view of a single frame;

[0033] Figure 13 is a perspective view of the frame including the cells;

[0034] Figure 14 is a perspective view of a single bus bar assembly as seen from the first side of the battery module;

[0035] Figure 15 is a perspective view of the first through third bus bar assemblies;

[0036] Figure 16 is a perspective view of the second bus bar assembly;

[0037] Figure 17 is a perspective view of the first bus bar assembly;

[0038] Figure 18 is a perspective view of the third bus bar assembly;

[0039] Figure 19 is a perspective view of the fourth and fifth bus bar assemblies;

[0040] Figure 20Is a perspective view of a separate bus bar assembly as seen from the second side of the battery module;

[0041] Figure 21 Is an end view of the first to third bus bar assemblies as seen in the direction of arrow A in Figure 15 ;

[0042] Figure 22 Is a perspective view of the first bus bar assembly;

[0043] Figure 23 Is an exploded view of the first bus bar assembly;

[0044] Figure 24 Is a perspective view of the fifth bus bar assembly;

[0045] Figure 25 Is an exploded view of the fifth bus bar assembly;

[0046] Figure 26 Is Figure 29 A detailed view of a cross-sectional view of the battery module shown by the dashed line in

[0047] Figure 27 Is a detailed view of a part of the battery module, showing the electrical connection between the negative terminal of the battery and the corresponding bus bar;

[0048] Figure 28 Is a detailed view of a part of the battery module, showing the electrical connection between the positive terminal of the battery and the corresponding bus bar;

[0049] Figure 29 Is a cross-sectional view of the battery module with the spacer structure omitted;

[0050] Figure 30 Is a cross-sectional view of the battery module including the spacer structure;

[0051] Figure 31 Is a perspective view of a separate spacer structure;

[0052] Figure 32 Is an end view of a separate spacer structure;

[0053] Figure 33 Is Figure 30 A detailed view of a cross-sectional view of the battery module shown by the dashed line in

[0054] Figure 34 Is an exploded perspective view of the box;

[0055] Figure 35 Is an exploded view of the battery module and the partition of the box;

[0056] Figure 36is a top view of a battery pack housing, where the lid and auxiliary structures are omitted to show the thermal management system, and a pump is schematically shown;

[0057] Figure 37 is a perspective view of a separate fluid delivery part of the thermal management system;

[0058] Figure 38 is a perspective view of a separate fluid delivery part of the thermal management system, showing the connection between the fluid delivery part and two boxes;

[0059] Figure 39 is a perspective view of a separate fluid return part of the thermal management system;

[0060] Figure 40 is a perspective view of a separate fluid return part of the thermal management system, showing the connection between the fluid return part and two boxes;

[0061] Figure 41 is an exploded perspective view of a box, where the box housing is omitted and the inlet plenum assembly is shown;

[0062] Figure 42 is a perspective view of a part of the box, showing the inlet plenum assembly;

[0063] Figure 43 is a perspective view of a part of the box, showing the inlet plenum assembly including a manifold part with an inlet opening connected to the inlet plenum assembly;

[0064] Figure 44 is along Figure 42 a cross-sectional view of the inlet plenum assembly seen along line 44-44;

[0065] Figure 45 is along Figure 42 a cross-sectional view of the inlet plenum assembly seen along line 45-45;

[0066] Figure 46 is along Figure 42 a cross-sectional view of the inlet plenum assembly seen along line 46-46;

[0067] Figure 47 is a perspective view of the module-facing surface of the inlet plenum assembly;

[0068] Figure 48 is Figure 47 an exploded perspective view of the inlet plenum assembly;

[0069] Figure 49 is an exploded perspective view of the box, where the box housing is omitted and the outlet plenum assembly is shown;

[0070] Figure 50Perspective view of a part of the cartridge, showing the outlet plenum assembly;

[0071] Figure 51 Perspective view of a part of the cartridge, showing the outlet plenum assembly including a fluid return branch line with an outlet opening connected to the outlet plenum assembly;

[0072] Figure 52 Is Figure 51 An enlarged perspective view of;

[0073] Figure 53 Perspective view of the module-facing surface of the outlet plenum assembly;

[0074] Figure 54 Is Figure 53 Exploded perspective view of the outlet plenum assembly of;

[0075] Figure 55 Side view of a separate pressure management system;

[0076] Figure 56 Exploded side view of the pressure management system, showing the relative positions of the lid and the container part of the battery pack housing;

[0077] Figure 57 End view of a separate pressure management system;

[0078] Figure 58 Top perspective view of the first bladder;

[0079] Figure 59 Is along Figure 58 Cross-sectional view of the first bladder seen along line 59-59 of;

[0080] Figure 60 Exploded perspective view of the second and third bladders and the protective housing;

[0081] Figure 61 Cross-sectional view of a part of the battery pack, showing details of the main fitting and the vent block;

[0082] Figure 62 Cross-sectional view of the vent block;

[0083] Figure 63 And Figure 64 Additional cross-sectional view of a part of the battery pack, showing details of the main fitting and the vent block;

[0084] Figure 65 Exploded view of the main fitting;

[0085] Figure 66 Cross-sectional view of a part of the main fitting. Detailed Description

[0086] Referring toFigure 1-7 , the battery pack 1 is configured to supply electrical power to a vehicle powertrain and can thus operate at a relatively high voltage. As used herein, the term high voltage refers to a voltage greater than 100V. For example, in some embodiments, the battery pack 1 can operate at 400V, while in other embodiments, the battery pack 1 can operate at 800V. The battery pack 1 includes a battery pack housing 2 for accommodating battery modules 40, and each battery module 40 includes an electrochemical cell 200. The battery pack housing 2 includes a container 4 and a lid 6 that closes the open end of the container 4, and the lid is connected to the open end of the container via a fluid-impermeable seal 8. The battery pack housing 2 has a flat shape. As used herein, the term "flat shape" refers to having a height hp that is relatively small compared to the length lp and width wp. In the battery pack housing 2, the height hp corresponds to the distance between the lid 6 and the bottom of the container 4.

[0087] The battery pack housing 2 is filled (e.g., completely filled, filled to overflow) with an engineered fluid and sealed to prevent leakage and / or evaporation of the engineered fluid. The engineered fluid has dielectricity, non-flammability, and chemical inertness. For example, the fluid can be ethoxy-nonafluorobutane, such as Novec TM 7200 manufactured by 3M Company in Minnesota, USA. The battery pack 1 includes a thermal management system 500 that provides active cooling to the cells 200 of each battery module 40 within the fluid-filled battery pack 1, as discussed in detail below. In addition, the battery pack 1 includes a pressure management system 300 that allows the enclosed, fluid-filled, and sealed battery pack housing 2 to accommodate changes in ambient temperature and pressure, as discussed in detail below.

[0088] In some embodiments, the battery pack 1 can include 12 battery modules 40 or more. In the illustrated embodiment, the battery pack 1 includes 24 battery modules 40. For ease of handling and assembly, the battery modules 40 are arranged in sub-assemblies each containing three battery modules 40(1), 40(2), 40(3). The sub-assemblies of battery modules 40 are referred to as "cartridges" 20. The three battery modules 40(1), 40(2), 40(3) of the sub-assembly are supported within a cartridge housing 22. In the illustrated embodiment, the battery pack housing 2 receives and supports eight cartridges 20, which are arranged in a two-dimensional array within the battery pack container 4.

[0089] Each battery module 40(1), 40(2), 40(3) of a given cartridge 20 can be electrically connected to the other battery modules of the given cartridge 20. Similarly, each cartridge 20 within the battery pack 1 is electrically connected to the other cartridges 20 of the battery pack 1. Depending on the needs of the specific application, the electrical connections can be in parallel, series, or a combination of parallel and series.

[0090] Refer to Figure 8, all of the battery modules 40 of the battery pack 1 are substantially the same. For this reason, only one battery module 40 will be described in detail, and identical or similar elements are denoted by the same reference numerals. The battery module 40 includes an array 202 of electrochemical cells 200. The cells 200 are supported within the battery module 40 by a frame 50 that holds the cells 200 in a two-dimensional array 202, as discussed in detail below. The frame 50 is disposed within a spacer structure 80 that provides fluid channels for guiding an engineered fluid that serves as a coolant to exposed portions of the cells 200, as discussed in detail below. The frame 50 and the spacer structure 80 cooperate to provide a battery module housing 46 that includes a positive terminal 42 and a negative terminal 44. The cells 200 are electrically connected to each other and to the positive or negative terminals 42, 44 of the respective battery module using bus bars 130 that are configured to simply and reliably accommodate high currents, as discussed in detail below.

[0091] Referring to Figure 9-10 and Figure 13 , the cell 200 is a cylindrical lithium-ion cell. Each cell 200 includes a cylindrical cell housing 203 having a container portion 204 and a lid portion 205 that closes an open end of the container portion 204. The lid portion 205 is disposed on a first end 207 of the cell 200 and seals the container portion 204 by means of an electrically insulating gasket 206. The container portion 204 includes a closed end disposed at a second end 208 of the cell housing 203, the second end 208 being opposite the first end 207 of the cell that includes the lid portion 205. The container portion 204 includes a cell housing sidewall 210 that projects from the closed end 208 and is perpendicular to the closed end 208. The container portion 204 extends along a longitudinal axis 212 of the cell that extends between the first end 207 and the second end 208 of the cell. That is, the longitudinal axis 212 extends parallel to the cell housing sidewall 210. Each cell 200 has the same shape and dimensions, including a cell diameter d1.

[0092] The electrode assembly 226 is sealed within the cell housing 203 together with an electrolyte to form a power generation and storage unit. The electrode assembly 226 includes a stacked arrangement of a positive electrode 218, a first separator 222, a negative electrode 220, and a second separator 224, wherein the stacked arrangement has been rolled up to provide a "jelly roll". One of the electrodes, such as the positive electrode 218, is electrically connected to the lid portion 205, which serves as the positive terminal 214 of the cell 200. Additionally, the other electrode, such as the negative electrode 220, is electrically connected to the container portion 204, which serves as the negative terminal 216 of the cell 200.

[0093] Due to the curved shape of the battery, cylindrical battery 200 may have a lower packaging efficiency in a battery module than some other battery types. To maximize the packaging efficiency of cylindrical battery 200, battery 200 is stored in battery module 40 in a "close-packed" configuration. As used herein, the term "close-packed" refers to a configuration in which batteries 200 are arranged in rows side by side. Further, when battery 200 is viewed in an end view ( Figure 9 ), alternating rows are relatively offset in a direction parallel to that row such that the centers 228 of the batteries 200 in one row are between the centers 228 of the batteries 200 in an adjacent row. Further, each battery 200 is in direct contact with adjacent batteries within its own row (i.e., 200(1), 200(2)) and is in direct contact with adjacent batteries in an adjacent row (i.e., 200(3), 200(4), 200(5), 200(6)). Sometimes, this battery configuration is also referred to as a "hexagonal packing" configuration. In the illustrated embodiment, array 202 includes 8 rows of batteries 200 and each row includes 38 batteries. In other embodiments, depending on the needs of a particular application, array 202 may include more or fewer rows and / or more or fewer batteries 200 per row. The batteries 200 in array 202 are aligned such that when the batteries 200 are viewed in a side view, the ends 207 or 208 of each battery 200 are arranged in a first plane P1 ( Figure 13 ), which is common to each battery 200 in array 202.

[0094] Reference Figure 11 , within array 202, batteries 200 are grouped in quadrants Q1, Q2, Q3, Q4 and all of the batteries 200 within a given quadrant have the same orientation such that terminals of the same polarity are arranged on the same side of the given quadrant. Further, when array 202 is viewed in a direction facing the battery ends 207, 208, the batteries 200 in adjacent quadrants have opposite polarities. For example, as Figure 10 shows, one side of array 202 is shown, whereby the batteries 200 can be seen in an end view. In Figure 10 , the first and second quadrants Q1, Q2 are side by side and cover the third and fourth quadrants Q3, Q4 which are also side by side. The batteries 200 in the first quadrant Q1 and the fourth quadrant Q4 have the same orientation, for example the orientation in which the second end 208 (and thus the negative terminal 216) of battery 200 is visible. Further, the batteries 200 in the second and third quadrants Q2, Q3 have the same orientation, for example the orientation in which the first end 207 (and thus the positive terminal 214) of battery 200 is visible. By grouping the batteries 200 in quadrants Q1, Q2, Q3, Q4, the electrical connections between the batteries 200 in array 202 provided via bus bars 130 are simplified.

[0095] ReferenceFigure 12 and Figure 13 Frame 50 holds the cells 200 in a closely packed arrangement. Frame 50 includes a cover plate 52, a bottom plate 54, a first end cap 56 that connects a first end of the cover plate 52 to a first end of the bottom plate 54, and a second end cap 58 that connects a second end of the cover plate 52 to a second end of the bottom plate 54. In addition, frame 50 includes a central wall 60 that joins the cover plate 52 to the bottom plate 54 and is disposed generally midway between the first and second end caps 56, 58. The first and second end caps 56, 58 and the central wall 60 are perpendicular to the cover plate 52 and the bottom plate 54. The cover plate 52, the bottom plate 54, the first and second end caps 56, 58, and the central wall 60 are thin plates having a width wf corresponding to the length lc of the cell 200, where the length lc of the cell 200 is the distance between a first end 207 (e.g., lid portion 205) and a closed second end 208. The cover plate 52 and the bottom plate 54 have a length adapted to the length la of the cell array 202, which in turn corresponds to the size of the rows of cells 200. In addition, the first and second end caps 56, 58 and the central wall 60 are sized to accommodate the height ha of the cell array 202.

[0096] Frame 50 surrounds the periphery of the cell array 202 and covers the side walls 210 of each cell in the array 202. In other words, the cells 200 are oriented such that the longitudinal axis 212 of each cell 200 is parallel to each of the cover plate 52, the bottom plate 54, the first and second end caps 56, 58, and the central wall 60. Thus, each of the first and second ends 207, 208 of the cells and thus the cell positive and negative terminals 214, 216 of each cell 200 are exposed at corresponding open sides 72, 74 of the frame 50.

[0097] The profiles of the cell-facing surfaces 62, 64, 66, 68, 70 of the cover plate 52, the bottom plate 54, the first and second end caps 56, 58, and the central wall 60 are shaped to accommodate the cylindrical shape of the cell side walls 210 of the outermost cells 200 of the array 202. For example, the cell-facing surfaces 62, 64, 66, 68, 70 may have a wavy profile for receiving and supporting the outermost cells of the array 202. In some embodiments, to further fix and hold the cells 200 in the desired closely packed configuration, an adhesive may be used to fasten the cell housing 203 of a given cell 200 to the cell housing 203 of each adjacent cell 200.

[0098] The outward-facing surface of each of the first end cap and the second end caps 56, 58 may include a first groove 76 that extends in the width direction of the first end cap and the second end caps 56, 58 (e.g., in a direction parallel to the longitudinal axis 212 of the battery 200). The first groove 76 has a curved concave surface for receiving and supporting the retaining bar 28, as discussed further below. The outward-facing surface of each of the first end cap and the second end caps 56, 58 may include a second groove 78 that extends in the height direction of the first end cap and the second end caps 56, 58 (e.g., in a direction perpendicular to the longitudinal axis 212 of the battery 200). The second groove 78 has a curved concave surface for receiving and supporting a wire harness (not shown).

[0099] Reference Figure 8 and Figure 14-21 ,The bus bar 130 provides battery terminal interconnection within the battery module 40. The bus bar 130 includes five bus bar components 130(1), 130(2), 130(3), 130(4), 130(5) that cooperate to electrically connect the batteries 200 of a given quadrant Q1, Q2, Q3, Q4 in parallel and provide a series electrical connection between the quadrants Q1, Q2, Q3, Q4 and the terminals 42, 44 of the battery module 40. For example, the first bus bar component 130(1) provides a parallel electrical connection between the negative terminals 216 of a first subset of the batteries 200 in the battery array 202, where the first subset of batteries 200 corresponds to the batteries 200 within the first quadrant Q1. In addition, the first bus bar component 130(1) serially connects the batteries 200 of the first quadrant Ql to the negative terminal 44 of the battery module.

[0100] The second bus bar component 130(2) provides a parallel electrical connection between the positive terminals 214 of a second subset of the batteries 200 in the battery array 202, where the second subset of batteries 200 corresponds to the batteries 200 within the second quadrant Q2. In addition, the second bus bar component 130(2) serially connects the batteries 200 of the second quadrant Q2 to the positive terminal 42 of the battery module.

[0101] The third bus bar component 130(3) provides a parallel electrical connection between the positive terminals 214 of a third subset of the batteries 200 in the battery array 202, where the third subset of batteries 200 corresponds to the batteries 200 within the third quadrant Q3. In addition, the third bus bar component 130(3) provides a parallel electrical connection between the negative terminals 216 of a fourth subset of the batteries 200 in the battery array 202, where the fourth subset of batteries 200 corresponds to the batteries 200 within the fourth quadrant Q4. In addition, the third bus bar component 130(3) serially connects the batteries 200 of the third quadrant Q3 to the batteries 200 of the fourth quadrant Q4.

[0102] The fourth bus bar assembly 130(4) provides a parallel electrical connection between the positive terminals 214 of a first subset of the cells 200 in the battery array 202, e.g., the cells 200 within the first quadrant Q1. In addition, the fourth bus bar assembly 130(4) provides a parallel electrical connection between the negative terminals 216 of a third subset of the cells 200 in the battery array 202, e.g., the cells 200 within the third quadrant Q3. Further, the fourth bus bar assembly 130(4) serially connects the cells 200 of the first quadrant Q1 to the cells of the third quadrant Q3.

[0103] The fifth bus bar assembly 130(5) provides a parallel electrical connection between the negative terminals 216 of a second subset of the cells 200 in the battery array 202, e.g., the cells 200 within the second quadrant Q2. In addition, the fifth bus bar assembly 130(5) provides a parallel electrical connection between the positive terminals 214 of a fourth subset of the cells 200 in the battery array 202, e.g., the cells 200 within the fourth quadrant Q4. Further, the fifth bus bar assembly 130(5) serially connects the cells 200 of the second quadrant Q2 to the cells of the fourth quadrant Q4.

[0104] Each of the five bus bar assemblies 130(1), 130(2), 130(3), 130(4), 130(5) includes a conductive substrate 138, an insulating layer 180 disposed on the cell terminal-facing side 132 of the substrate 138, and an electrical connector 160 that provides an electrical connection between the substrate 138 and each respective cell terminal 214 or 216.

[0105] The substrate 138 is a rigid, conductive thin plate. The substrate 138 includes a first side 132 facing the cells 120, a second side 134 opposite the first side 132, and an outer peripheral edge 136. Each substrate 138 includes at least one tab 148 protruding from the outer peripheral edge 136. The tab 148 is folded towards the first side 132 of the substrate such that it extends perpendicular to the first side 132 of the substrate. The tab 148 allows voltage and temperature sensor leads to be electrically connected to the substrate 138. Further, fasteners (not shown) are used to fix the voltage and temperature sensor leads together with the substrate 138 to the frame end caps 56, 58 via openings in the tabs 48.

[0106] Each substrate 138 includes an α portion 140 corresponding to the area that forms a parallel electrical connection between the substrate 138 and the cells 200 of a given quadrant, and a β portion 150 corresponding to the area that provides a serial electrical connection, e.g., between adjacent α regions or between an α region and the module terminals 42, 44. The outer peripheral edge 132 of the α portion 140 curves to conform to the profile of the battery array 202.

[0107] The first, second, and third bus bar assemblies 130(1), 130(2), 130(3) provide electrical connections between the cells 200 on the first side of the cell array 202, and the substrates 138 of the first, second, and third bus bar assemblies 130(1), 130(2), 130(3) are generally L-shaped. The first leg of the "L" covers the first side of the cell array (e.g., covers the end of the cell including the cell terminals 214 or 216). The first leg of the "L" corresponds to the α portion 140 of the substrate 138. In addition, the second leg of the "L" is perpendicular to the first leg and covers a portion of the frame 50 (e.g., covers the side wall of the cell 200). The second leg of the "L" corresponds to the β portion 150 of the substrate 138.

[0108] The α portion 140 is located in a second plane P2 parallel to the first plane P1, and the ends of the cells 200 are aligned in the first plane P1. The α portion 140 includes main connection through-holes 142. A main connection through-hole 142 is provided for each cell 200 of the quadrant, and each main connection through-hole 142 is aligned with one end of the corresponding cell 200 so as to expose the cell terminals 214 or 216. The main connection through-holes 142 are circular, and their diameter d2 is smaller than the diameter d1 of the cells 200. The main connection through-holes 142 expose the ends of the cells so that electrical connections can be made between the exposed cell terminals 214 or 216 and the α portion 140 using electrical connectors 160, such as wire bonds. The α portion also includes main flow-through holes 144 that are aligned with small gaps between the side walls 210 of adjacent cells 200. As a reflection of the hexagonal stacking arrangement of the cells 200, there are six main flow-through holes 144 arranged around the periphery of each main connection through-hole 142. The main flow-through holes 144 have a small diameter d3 to correspond to the small size of the gaps, and their diameter is smaller than the diameter of the main connection through-holes 142. For example, in the illustrated embodiment, the diameter d3 of the main flow-through holes 144 is about 10% to 25% of the diameter d2 of the main connection through-holes 142.

[0109] The β portion 150 is located in a third plane P3 that is perpendicular to the second plane P2. In the substrates 138 of the first and second busbar assemblies 130(1), 130(2), the β portion 150 covers the frame cover plate 52. The β portion 150 of the first busbar assembly 130(1) is electrically connected to the negative terminal 44 of the battery module, and the β portion 150 of the second busbar assembly 130(2) is electrically connected to the positive terminal 42 of the battery module. In some embodiments, the β portions 150 of the first and second busbar assemblies 130(1), 130(2) may be integrally formed with the corresponding terminals 42, 44, and in other embodiments, the β portions 150 of the first and second busbar assemblies 130(1), 130(2) may be joined to the corresponding terminals, for example, by welding. In the illustrated embodiment, the negative terminal 44 of the battery module projects integrally from an edge of the β portion 150 of the first busbar assembly 130(1), and the positive terminal 42 of the battery module projects integrally from an edge of the β portion 150 of the second busbar assembly 130(2). Thus, the terminals 42, 44 of the battery module are located in the same plane as the β portions 150 of the first and second busbar assemblies 130(1), 130(2). In the substrate 138 of the third busbar assembly 130(3), the β portion 150 covers the frame bottom plate 54 and provides a series electrical connection between the third quadrant Q3 and the fourth quadrant Q4.

[0110] In the substrates 138 of the first, second, and third busbar assemblies 130(1), 130(2), 130(3), the thickness tb of the β portion 150 is greater than the thickness ta of the α portion 140, where the thickness of the substrate of the α portion corresponds to the distance between the first side 132 and the second side 134 ( Figure 21 ). The greater thickness 150 of the β portion accommodates the large current in this region. Additionally, the β portions 150 of the first, second, and third busbar assemblies 130(1), 130(2), 130(3) may include strip-shaped openings 152. The openings 152 receive the tabs 55 that project from the outward-facing surfaces of the frame cover plate and bottom plate 52, 54, whereby the openings 152 allow for the correct alignment and orientation of the busbar assemblies 130(1), 130(2), 130(3) relative to the frame 50 and are used to maintain the correct alignment of the busbar assemblies 130(1), 130(2), 130(3) relative to the frame 50.

[0111] The fourth and fifth busbar assemblies 130(4), 130(5) provide electrical connections between the cells 200 on the second side of the battery array 202. The substrates 138 of the fourth and fifth busbar assemblies 130(4), 130(5) are generally planar, cover the second side of the battery array and include two α portions 140, wherein β portions 150 are arranged between the α portions 140 and are coplanar with the α portions 140. The substrates 138 of the fourth and fifth busbar assemblies 130(4), 130(5) have a uniform thickness. The fourth and fifth busbar assemblies 130(4), 130(5) are arranged side by side in the same plane P5. The fourth and fifth busbar assemblies 130(4), 130(5) are spaced apart within the plane P5. The plane P5 is parallel to the planes P1 and P2.

[0112] Referring Figure 22-26 and Figure 29 , an insulating layer 180 is disposed on the side 132 of the substrate 138 facing the battery terminals to be located between the α portions 140 of the five busbar assemblies 130(1), 130(2), 130(3), 130(4), 130(5) and the battery terminals 214, 216. The insulating layer 180 is electrically insulating and thermally insulating. For example, in some embodiments, the insulating layer may have a dielectric breakdown voltage of 2.6 kV and may have a thermal conductivity of 0.17 W / mK, so that it can adapt to a temperature of at least 800 degrees Celsius without failure. In addition, the insulating layer 180 provides a flame barrier. For example, in some embodiments, when classified using the UL94 test method (e.g., the plastic flammability standard published by Underwriters Laboratories), the insulating layer 180 has a flame retardant rating of V-0, 5VA.

[0113] The insulating layer 180 includes secondary connection through-holes 188. The secondary connection through-holes 188 are provided for each cell 200 of the quadrant, and each secondary connection through-hole 188 is aligned with a corresponding primary connection through-hole 142, thereby exposing the ends of the cells, so that electrical connections can be made between the exposed battery terminals 214 or 216 and the α portions 140 using electrical connectors 160. The secondary connection through-holes 188 are circular and have a diameter d4 that is smaller than the diameter d1 of the cell 200 and the diameter d2 of the primary connection through-holes 142. Since the diameter of the secondary connection through-holes 188 is smaller than the diameter of the primary connection through-holes 142, an insulating boundary or edge is provided within each primary connection through-hole 142 to reduce the likelihood of a short circuit between the substrate 138 and the battery terminals 214, 216 near the primary connection through-holes 142. The insulating layer 180 also includes secondary flow-through holes 190 that are aligned with the primary flow-through holes 144 and have the same diameter d3 as the primary flow-through holes 144.

[0114] In some embodiments, the insulating layer 180 may be in the form of a sheet having a first side 182 facing the α portion 140 and a second side 184 facing the battery array 202. The sheet used to form the insulating layer 180 may be a paper sheet, a ceramic sheet, a paper sheet coated with ceramic, a film, or other suitable thin material. The first side 182 of the sheet-like insulating layer 180 may include an adhesive coating that fixes the insulating layer 180 to the α portion 140. Additionally, the second side 184 of the insulating layer 180 may include an adhesive coating that fixes the insulating layer to the exposed battery ends. For example, the first and second sides 182, 184 of the insulating layer 180 may include a pressure-sensitive adhesive coating. In other embodiments, the insulating layer 180 may be a coating disposed on (e.g., bonded to) the α portion 140 of the substrate 138 facing the battery side 132. The coating may be applied to the surface by any suitable method, such as a sintering process or a vapor deposition process.

[0115] Referring Figure 27-28 , for each of the battery terminals 214, 216, the electrical connector 160 extends between the battery terminals 214, 216 and the α portion 140 of the corresponding bus bar assemblies 130(1), 130(2), 130(3), 130(4), 130(5) (e.g., the bus bar assemblies facing the battery terminals) and provides an electrical connection. For example, the electrical connector 160 may be a bonding wire, but is not limited to this type of electrical connector. As used herein, the term "bonding wire" refers to an electrical connector in the form of a thin wire composed of high-purity gold, aluminum, or copper, which is attached to the substrate 138 at one end and to the terminals 214, 216 at the other end via a bonding wire process. Other suitable electrical connectors may be used instead of bonding wires depending on the needs of the specific application. For example, another suitable electrical connector may include a direct weld between the battery terminals 214, 216 and the α portion 140 of the corresponding bus bar assemblies 130(1), 130(2), 130(3), 130(4), 130(4), 130(5).

[0116] In the battery module 40, the positive terminal 214 of each battery 200 is connected to the α portion 140 of one bus bar assembly 130 via a first electrical connector 160(1) Figure 28 ), and the negative terminal of the battery 200 is connected to the α portion 140 of another bus bar assembly via a second electrical connector 160(2) Figure 27)。In the illustrated embodiment, the current-carrying capacity of the first electrical connector 160(1) is different from that of the second electrical connector 160(2). For example, the current-carrying capacities of the electrical connectors 160(1) and 160(2) are asymmetric. In particular, the current-carrying capacity of the first electrical connector 160(1) is less than that of the second electrical connector. By providing the first and second electrical connectors 160(1) and 160(2) with the current-carrying capacity of the first electrical connector 160(1) being less than that of the second electrical connector 160(2), each battery is electrically connected to the corresponding bus bar assembly 130, such that the electrical connection to the positive terminal 214 of the battery fails prior to the electrical connection to the negative terminal 216 of the battery, thereby disconnecting the internal circuit of the battery module 40.

[0117] In the illustrated embodiment, the difference in the current-carrying capacities of the first and second electrical connectors 160(1) and 160(2) is achieved by providing a single bonding wire as the first electrical connector 160(1) and providing two bonding wires (e.g., double bonding wires) as the second electrical connector 160(2), wherein each bonding wire has the same current-carrying capacity.

[0118] In other embodiments, the difference in the current-carrying capacities of the first and second electrical connectors 160(1) and 160(2) can be achieved by providing a single first bonding wire as the first electrical connector 160(1) and a single second bonding wire as the second electrical connector 160(2), wherein the first bonding wire has a lower current-carrying capacity than the second bonding wire. For example, this can be achieved by providing a first bonding wire having a diameter smaller than that of the second bonding wire.

[0119] In other embodiments, the difference in the current-carrying capacities of the first and second electrical connectors 160(1) and 160(2) can be achieved by providing a single first bonding wire as the first electrical connector 160(1) and a direct weld between the substrate 138 and the negative terminal 216 as the second electrical connector 160(2).

[0120] In other embodiments, the difference in the current-carrying capacities of the first and second electrical connectors 160(1) and 160(2) can be achieved by providing a first conductive bar or lead as the first electrical connector 160(1) and a second conductive bar or lead as the second electrical connector 160(2), wherein the first conductive bar includes a fuse. For example, this can be achieved by providing a necked-down portion for the first conductive strip that fails at a lower current than the rest of the conductive strip.

[0121] Reference Figure 8 and Figure 30-33, a frame 50, includes an array 202 of cells 200 supported therein, and busbars 130 covering the cell ends 207, 208 and the cover plates and bottom plates 52, 54 of the frame 50, arranged within a spacer structure 80. The spacer structure 80 is a bar-shaped rectangular thin-walled tube, which includes an open first end 82 of the spacer structure, an open second end 84 of the spacer structure opposite to the first end 82 of the spacer structure, and a side wall 85 of the spacer structure extending between the first end 82 and the second end 84 of the spacer structure.

[0122] The side wall 85 of the spacer structure has a rectangular shape when viewed facing the first end or the second end 82, 84 of the spacer structure, and thus includes four wall portions 86, 90, 94, 96. In particular, the side wall 85 of the spacer structure includes a first wall portion 86, a second wall portion 90 spaced apart from and parallel to the first wall portion 86, a third wall portion 94 perpendicular to the first wall portion 86 and connecting the first wall portion 86 to the second wall portion 90, and a fourth wall portion 96 spaced apart from the third wall portion 94 and parallel to the third wall portion 94. The fourth wall portion 96 connects the first wall portion 86 to the second wall portion 90.

[0123] The first, second, third, and fourth wall portions 86, 90, 94, 96 cooperate to define an internal space 104 of the spacer structure. The frame 50 is arranged within the internal space 104 of the spacer structure such that the first wall portion 86 of the spacer structure covers an α portion 140 of the first, second, and third busbar assemblies 130(1), 130(2), 130(3) on a first side of the cell array 202. In addition, the second wall portion 90 of the spacer structure covers an α portion 140 of the fourth and fifth busbar assemblies 130(4), 130(5) on a second side of the cell array 202. Thus, each of the first end 207 and the second end 208 of the cell faces the first wall portion 86 or the second wall portion 90. In addition, the first end cover and the second end cover 56, 58 of the frame are arranged in the open first end and second end 82, 84 of the spacer structure.

[0124] The inner surface 88 of the first wall portion 86 and the inner surface 92 of the second wall portion 90 each include a groove 98 extending from the first end 82 of the spacer structure to the second end 84 of the spacer structure. The groove 98 serves as a fluid passage within the battery module 40, and the same engineering fluid used for injecting into the battery pack 1 is actively pumped through the groove 98, as further discussed below. The number of grooves 98 provided on each of the first wall portion and the second wall portion 86, 90 corresponds to the number of rows of the batteries 200 in the battery array 202. Each groove 98 is aligned with a row of the battery array 202 and opens towards the battery array 202, whereby the battery ends 207, 208 and the electrical connectors 160 are exposed to the cooling effect of the engineering fluid flowing through the groove 98. In other words, each groove 98 provides a coolant fluid passage 102 flowing between the spacer structure 80 and the battery array 202. For this purpose, the shape and size of the groove 98 are designed to accommodate sufficient coolant fluid flow to keep the battery 200 at a desired temperature. In addition, the shape and size of the groove 98 can be designed to accommodate the airflow discharged from the battery 200. In the illustrated embodiment, when the spacer structure 80 is viewed in cross-section, each groove 98 has a rectangular shape, wherein the bosses 100 are arranged between adjacent grooves 98 and separate the adjacent grooves 98.

[0125] Fluid enters each groove 98 at the first end 82 of the spacer structure and can leave the groove 98 at the second end 84 of the spacer structure. The engineering fluid within the groove 98 flows past the positive and negative terminals of the battery including the electrical connector 160. In some embodiments, the electrical connector 160 is aligned with the flow direction (e.g., oriented parallel to the extended direction of the groove 98), whereby the fluid pressure loss due to the presence of the electrical connector 160 in the fluid passage 102 is minimized.

[0126] Since the battery pack 1 is filled with engineering fluid, the components of the battery module 40 including the frame 50 and the spacer structure 80 are not fluid-sealed to each other or to other components of the battery module 40. Although the fluid is guided through the fluid passage 102 defined by the groove 85, the fluid flow through the battery module 40 is not blocked, including the flow through between the side walls 210 of adjacent batteries 200 and through the main and secondary flow holes 144, 190 of the bus bar assembly 130 of the battery module 40.

[0127] The frame 50 and the spacer structure 80 are formed of a dielectric material, such as a polymer. The spacer structure 80 can be manufactured as an integral structure (not shown), or can be manufactured as two U-shaped halves 80(1), 80(2) for ease of assembly with the frame 50.

[0128] Refer to Figure 4-5 and Figure 34-35, as described above, each cartridge 20 includes three battery modules 40(1), 40(2), 40(3) supported within a cartridge housing 22. The cartridge housing 22 includes a rigid U-shaped upper portion 24 and a rigid U-shaped lower portion 26 that cooperate to form a tubular cartridge housing 22 having an open end 23. In some embodiments, the upper portion 24 and the lower portion 26 are formed of steel.

[0129] The three battery modules 40(1), 40(2), 40(3) are arranged side by side within the cartridge housing 22, and a separator 110 is disposed between each adjacent battery module 40. In particular, a first separator 110(1) is disposed between a first wall portion 86 of the first battery module 40(1) and a second wall portion 90 of the second battery module 40(2), and a second separator 110(2) is disposed between a first wall portion 86 of the second battery module 40(2) and a second wall portion 90 of the third battery module 40(3). In this configuration, the battery ends 207, 208 of the batteries 200 of one battery module 40 face the battery ends 207, 208 of the batteries 200 of the adjacent battery module 40. By placing the separator 110 between the corresponding wall portions 89, 90 of the adjacent modules 40(1), 40(2), 40(3), the separator 110 can serve as a thermal and mechanical barrier in the case of battery ventilation and / or thermal runaway of the batteries 200 of one of the modules 40. To this end, the separator 110 is an airtight rigid thin metal plate and has a melting temperature higher than 1000 degrees Celsius. In the illustrated embodiment, the separator 110 is a thin steel plate.

[0130] The battery modules 40(1), 40(2), 40(3) are prevented from exiting the open end 23 of the cartridge housing by a cylindrical retaining rod 28( Figure 5 ). The retaining rod 28 cooperates with first grooves 76 of the frame first end cap and second end cap 56, 58 and passes through openings 118 along the outer periphery of the separators 110(1), 110(2) to retain the battery modules 40(1), 40(2), 40(3) within the cartridge housing 22.

[0131] The three battery modules 40(1), 40(2), 40(3) are arranged within the cartridge housing 22 such that the battery module terminals 42, 44 project outwardly from the cartridge housing 22. In addition, at each open end 23 of the cartridge housing 22, the polarities of the three projecting battery module terminals 42, 44 alternate in polarity.

[0132] Reference Figure 36-40, the battery pack 1 includes a thermal management system 500 that actively directs an engineering fluid to each battery module 40 disposed in the battery pack housing 2. The thermal management system 500 includes a fluid pump 680, a fluid delivery line 682 that receives pressurized fluid from the fluid pump 680 and delivers it to the cartridge 20, and a fluid return line 692 that collects fluid from the cartridge 20 and returns it to the fluid pump 680. In the illustrated embodiment, the fluid pump 680 is located outside the battery pack housing 2, but in other embodiments, the fluid pump 680 may be disposed within the battery pack housing 2.

[0133] Within the battery pack housing 2, the fluid delivery line 682 divides into four delivery branch lines 684(1), 684(2), 684(3), 684(4). Each delivery branch line 684(1), 684(2), 684(3), 684(4) delivers fluid to two adjacent cartridges 20. To this end, each delivery branch line 684(1), 684(2), 684(3), 684(4) includes a first manifold portion 685(1) that directs fluid to the inlet plenum assembly 502 of the first of the adjacent cartridges 20, and a second manifold portion 685(2) that directs fluid to the inlet plenum assembly 502 of the second of the adjacent cartridges 20. The inlet plenum assemblies 502 of each cartridge 20 are substantially identical, and the inlet plenum assembly 502 will be described in detail below. Each of the first and second manifold portions 685(1), 685(2) is a tube having an inlet end 686, an opposite outlet end 687, and three delivery ports 688. The inlet end 686 of the first manifold portion 685(1) is connected to the corresponding branch line 684 of the fluid delivery line 682, and the outlet end 687 of the first manifold portion 685(1) is connected to the inlet end 686 of the second manifold portion 685(2). The outlet end 687 of the second manifold portion 685(2) is covered (e.g., plugged). The three delivery ports 688 are respectively connected to the inlet openings 522 of the corresponding inlet plenum assemblies 502 and provide fluid to the inlet plenum assemblies 502 in parallel.

[0134] Each delivery port 688 may include an orifice balancer 690( Figure 44-46 ). The orifice balancer 690 is a ring disposed within the delivery port 688, and the size of the inner surface 692 of the orifice balancer 690 determines the flow rate through the delivery port 688. By appropriately selecting the size of the orifice balancer 690, the fluid flow rate of the delivery port 688 can be controlled and adjusted.

[0135] Each cartridge 20 includes an outlet plenum assembly 582 having an outlet opening 622 and an outlet line 626. The outlet plenum assemblies 582 of each cartridge 20 are substantially identical, and the outlet plenum assembly 582 will be described in detail below. The outlet lines 626 from each cartridge 20 are connected to one of two return branch lines 694, and the two return branch lines 694 merge into a fluid return line 692.

[0136] Referring Figure 41-48 , the inlet plenum assembly 502 closes one of the two open ends 23 of the cartridge housing 22 and directs fluid to each of the battery modules 40(1), 40(2), 40(3) disposed within the cartridge 20. The inlet plenum assembly 502 includes an inlet plenum chamber 504 and an inlet diverter 540 disposed between the inlet plenum 504 and each of the battery modules 40(1), 40(2), 40(3).

[0137] The inlet plenum assembly 502 simultaneously distributes fluid to each of the battery modules 40(1), 40(2), 40(3) of the cartridge 20. To this end, the inlet plenum chamber 504 and the inlet diverter 540 cooperate to simultaneously direct fluid to fluid channels 102 disposed within the spacer structure 80 of each of the battery modules 40(1), 40(2), 40(3), as will now be described.

[0138] The inlet plenum chamber 504 includes an end plate 506 parallel to the end caps 56, 58 of the frame 50 and an edge 514 projecting from the module-facing surface 508 of the end plate 506. The edge 514 extends along a portion of the outer peripheral edge 512 of the end plate 506. In the illustrated embodiment, the end plate 506 has a rectangular profile, and the edge 514 extends along three sides of the end plate 506. In use, the edge 514 covers the cartridge housing 22. Additionally, the inlet plenum chamber 504 includes a pair of guide rails 518 projecting from the module-facing surface 508 of the end plate 506. The guide rails 518 extend linearly parallel to the first and second wall portions 86, 90 of the frame. The guide rails 518 are aligned with each partition 110 and are thus configured to receive fluid diverted from the inlet diverter 540 and direct it to the fluid channels 102.

[0139] The end plate 506 of the inlet plenum chamber includes three fluid inlet openings 522 that are connected to the fluid delivery ports 688 of the manifold section 685 and receive fluid from the fluid delivery line 682. The fluid inlet openings 522 are arranged in a straight line, and tracks 518 are arranged between each adjacent fluid inlet opening 522. Each fluid inlet opening 522 faces a respective one of the three battery modules 40(1), 40(2), 40(3) of the cartridge 20. Additionally, each fluid inlet opening 522 is centered on the end caps 56, 68 of the frame 50 of the respective battery module 40 and is aligned with the surface of the inlet diverter 540, as discussed further below.

[0140] Each fluid inlet 522 is surrounded by a necked boss 524 that projects outward from the outward-facing surface 516 of the end plate 506. The boss 524 is shaped and sized to be received in and form a mechanical connection with the delivery port 688. For example, the boss 524 may be press-fit connected to the output port 688. An orifice balancer 690 ( Figure 44-46 ) is disposed in the output port 688 and is sandwiched between the inner surface of the output port 688 and the terminus 526 of the necked boss 524. As previously described, the orifice balancer 690 enables the inlet plenum assembly 502 to supply fluid to one of the battery modules (e.g., the first battery module 40(1)) at a first fluid flow rate and to another of the battery modules (e.g., the second battery module 40(2)) at a second fluid flow rate, where the first fluid flow rate is different from the second fluid flow rate. This is achieved by setting an appropriately sized orifice balancer in the delivery port 688.

[0141] The end plate 506 of the inlet plenum chamber includes snap-fit clips 528 that project outward from the outward-facing surface 516 of the end plate. The clips 528 receive and support one of the first manifold section and the second manifold section 685(1), 685(2).

[0142] An inlet diverter 540 is provided for each of the battery modules 40(1), 40(2), 40(3) of the cartridge 20 and is disposed between the end plate 506 of the inlet plenum chamber and the frame end caps 56, 58 of the respective battery modules 40(1), 40(2), 40(3). The inlet diverter 540 is a formed rigid plate configured to receive fluid exiting the fluid inlet opening 522 and direct the fluid to the fluid channels 120 of the respective battery modules 40(1), 40(2), 40(3). The inlet diverter 540 includes a flat first portion 548 adjacent to the outer peripheral edge 546 of the inlet diverter 540 and a dome-shaped (e.g., bulged) second portion 550 surrounded by the first portion 548. The first portion 548 is parallel to the end plate 506. The second portion 550 projects toward the end plate 506 and is aligned with the fluid inlet opening 522. In the illustrated embodiment, the first portion 548 of the inlet diverter 540 is fixed to the end caps 56, 58 of the frame 50 of the respective battery modules 40(1), 40(2), 40(3) together with the end plate 506. In the illustrated embodiment, fasteners such as screws 522 are used to fix the diverter 540 and the end plate 506 to the frame 50, and the fastener openings in the end plate 506 are surrounded by spacers 530 that provide a spacing between the end plate 506 and the diverter 504. The inlet diverter 540 directs the fluid to the fluid channels 120 while diverting the fluid away from first and second grooves 76, 78 provided in the outward-facing surfaces of the respective frame end caps 56, 58.

[0143] Reference Figure 49-54, the outlet gas collection assembly 582 closes the other of the two open ends of the cartridge housing 22. That is, the outlet gas collection assembly 582 and the inlet gas collection assembly 502 are arranged at opposite ends of the cartridge housing 22. The outlet gas collection assembly 582 collects the fluid discharged from the grooves 98 (e.g., fluid channels 102) of the spacer structure 80 of the battery module. The outlet gas collection assembly 582 includes an outlet gas collection chamber 584 and outlet diverters 640 arranged between each battery module 40(1), 40(2), 40(3) and the outlet gas collection chamber 584. The outlet gas collection chamber 584 is similar to the inlet gas collection chamber 504. For this reason, the same reference numerals are used to refer to the same elements, and the description of the common elements will not be repeated. The outlet gas collection chamber 584 differs from the inlet gas collection chamber 504 in that the inlet opening 522, the necked boss 524 and the guide rail 518 are omitted. In addition, the outlet gas collection chamber includes a single outlet opening 622, which is arranged on the outward-facing surface of the edge 514 and is in fluid communication with the space within the outlet gas collection chamber 584. The outlet diverter 640 is the same as the inlet diverter 540. Similarly, the same reference numerals are used to refer to the same elements. The outlet gas collection assembly 582 allows the fluid leaving each fluid channel 120 of the spacer structure 80 to be collected in the outlet gas collection chamber 584 and guided to the outlet opening 622. The outlet opening 622 is connected to the fluid return line 692 via an outlet line 626 and a return branch line 694.

[0144] Referring Figure 55-60 , the battery pack 1 includes a pressure management system 300 that provides passive management of the pressure within the sealed battery pack housing 2. The pressure management system 300 can be advantageous, for example, when the engineering fluid has a high coefficient of expansion and may be sensitive to temperature and / or altitude changes. The pressure management system 300 includes at least one flexible and expandable pressure compensation device 330 arranged within the battery pack housing 2, a vent block 302 arranged on the outer surface of the battery pack housing 2, and fittings 380, 480 that provide fluid communication between the pressure compensation device 330 and the vent block 302.

[0145] In the illustrated embodiment, the pressure compensation device 330 is a set of independent, serially-connected flexible expandable bladders 340. The bladders 340 act like lungs in that the bladders 340 expand or contract to accommodate volume changes of the engineered fluid within the sealed battery pack housing 2, such as those caused by pressure and temperature conditions around the battery pack housing 2. The bladders 340 are a set of three independent bladders 340(1), 340(2), 340(3) that are serially connected via primary and secondary fittings 380, 480. The first bladder 340(1) is connected to and in fluid communication with the vent block 302 via the primary fitting 380, and is also connected to and in fluid communication with the second bladder 340(2) via the same primary fitting 380. The second bladder 340(2) is also connected to and in fluid communication with the third bladder 340(3) via the secondary fitting 480.

[0146] Each of the bladders 340(1), 340(2), 340(3) is an enclosed bag formed of a material impermeable to gas and moisture, the material being flexible enough to allow the bladders 340 to expand and contract. Additionally, each of the bladders 340(1), 340(2), 340(3) is flexible enough to generally conform to the shape of adjacent structures within the battery pack 1, including the inner surface of the battery pack housing 2, the outer surfaces of the cartridge housing 22 disposed within the battery pack housing 2, and other auxiliary structures.

[0147] In the illustrated embodiment, each of the bladders 340(1), 340(2), 340(3) is formed of a laminate having a metal film layer and a polymer layer. In one example, the laminate may have three layers, including an outer metal film layer, a polyethylene terephthalate (PET) film intermediate layer, and an inner polypropylene film layer. In another example, the laminate may have three layers, including an outer PET film layer, a metal foil intermediate layer, and an inner polypropylene film layer.

[0148] The number of bladders 340 and the size of each bladder 340 depend on the requirements of the specific application. In the illustrated embodiment, the bladders 340(1), 340(2), 340(3) each have a unique shape and size, and their shape and size are adapted to fit within the available space within the battery pack 1 that houses the cartridge 20. The cartridge 20 is arranged in a single layer within the battery pack container 4 and is divided into two groups. The two groups of cartridges 20 are separated by a gap 9( Figure 2 , Figure 36 ) that receives the fluid delivery and return lines 682, 692 of the thermal management system and other auxiliary structures and devices (not shown). The bladders 340(1), 340(2), 340(3) are arranged within the battery pack housing 2 around the cartridge 20, as discussed in detail below.

[0149] The first bladder 340(1) is larger than the second and third bladders 340(2), 340(3) and is arranged between the cassette 20 and the lid 6. The first bladder 340(1) can be formed, for example, by laminating a first sheet 341 with a second sheet 342 and sealing the outer peripheries of the first and second sheets 341, 342 along a sealing line 348(1) to form a closed first internal space 358(1). The outer peripheral edge 356(1) can be sealed, for example, by heating. The first bladder 340(1) has a length and width sufficient to cover each of the eight cassettes 20 and has a very flat cross-section. In other words, the height h1 of the first bladder 340(1) is very small relative to its length l1 and / or width w1, where the height h of each bladder 340 is parallel to the height hp of the battery pack housing 2. For example, when the first bladder 340(1) is not inflated, the height h1 of the first bladder 340(1) can correspond to approximately the thickness of the two sheets 341, 342 of the material used to form the first bladder 340(1).

[0150] The first bladder 340(1) includes a first opening 351 that is formed in the first sheet 341 at a position spaced apart from the sealing line 348(1) of the first bladder 340(1). The shape and size of the first opening 351 are designed to receive a first portion 440 of the main fitting 380 therethrough, and the first sheet 341 is sealed to the first portion 440 of the main fitting 380 at the first opening 351.

[0151] The first bladder 340(1) includes a second opening 352 that is formed in the second sheet 342 at a position spaced apart from the sealing line 348(1) of the first bladder 340(1). The second opening 352 is aligned with the first opening 351 in a direction parallel to the height h1. In addition, the shape and size of the second opening 352 are designed to receive a second portion 442 of the main fitting 380 therethrough, and the second sheet 342 is sealed to the second portion 442 of the main fitting 380 at the second opening 352.

[0152] In addition, the first bladder 340(1) includes a pair of sealed through-holes 358 at a position spaced apart from the outer peripheral edge 356 of the bladder. The through-holes 358 allow auxiliary components of the battery pack 1 to pass through the first bladder 340(1). For example, in the illustrated embodiment, the through-holes 358 allow a filling tube to pass through the first bladder 340(1). In the illustrated embodiment, the through-holes 358 are arranged near the first and second openings 351, 352 such that one through-hole 358 is arranged on each opposite side of the first and second openings 351.

[0153] The second bladder 340(2) is arranged in the gap 9 between two sets of cassettes 20 and relative to Figure 1The orientation of the battery pack 1 shown is located below the first bladder 340(1). Compared with the first bladder 341(1), the bladder 340(2) has an irregular shape, a relatively high profile, and a width corresponding to the width of the gap in which it is located. For example, the second bladder 340(2) can be formed by laminating the laminated third sheet 343 and the laminated fourth sheet 344, and sealing the outer peripheral edges 356(2) of the third sheet and the fourth sheet 343, 344 along the sealing line 348(2) to form a closed second internal space 358(2). The outer peripheral edge 356(2) can be sealed, for example, by heating. The second bladder 340(2) includes a third opening 353 formed in the third sheet 343 at a position spaced apart from the sealing line 348(2) of the second bladder 340(2). The shape and size of the third opening 353 are designed to receive the third part 446 of the main fitting 380 through it, and the third sheet 343 is sealed to the third part 446 of the main fitting 380 at the third opening 353.

[0154] In addition, the second bladder 340(2) includes a fourth opening 354 formed in the third sheet 343 at a position spaced apart from the sealing line 348(2) of the second bladder 340(2). The fourth opening 354 is located at the opposite end of the second bladder 340(2) relative to the third opening 353. The shape and size of the fourth opening 354 are designed to receive one end 481 of the secondary fitting 480, and the third sheet 343 is sealed to one end of the secondary fitting 480 at the fourth opening 354.

[0155] The third bladder 340(3) is arranged in the gap 9 between the two sets of boxes 20 and is adjacent to the second bladder 340(2) within the gap 9 (e.g., end to end). Similar to the bladder 340(2), the third bladder 340(3) is located below the first bladder 340(1). The third bladder 340(3) has a generally rectangular shape, and its width corresponds to the width of the gap in which it is located. The height of the third bladder 340(3) is lower than that of the second bladder 340(2). For example, the third bladder 340(3) can be formed by laminating the laminated fifth sheet 345 and the laminated sixth sheet 346, and sealing the outer peripheral edges 356(3) of the fifth sheet and the sixth sheet 345, 346 along the sealing line 348(3) to form a closed third internal space 358(3). The outer peripheral edge 356(3) can be sealed, for example, by heating. The third bladder 340(3) includes a single opening, such as a fifth opening 355 formed in the fifth sheet 345 at a position spaced apart from the sealing line 348(3) of the third bladder 340(3). The shape and size of the fifth opening 355 are designed to receive the opposite end 482 of the secondary fitting 480, and the fifth sheet 345 is sealed to the opposite end 482 of the secondary fitting 480 at the fifth opening 355.

[0156] Reference Figure 61-64, the vent block 302 is in fluid communication with the internal spaces 358(1), 358(2), 358(3) of the pressure compensation device 330 and allows the internal spaces to communicate with the atmosphere surrounding the battery pack 2. The vent block 302 has a rectangular structure and is arranged on the outer surface of the battery pack lid 6. The vent block 302 includes an end 304 facing the lid, an outward-facing end 306 opposite the end 304 facing the lid, and four side surfaces 308, 310, 312, 314 extending between the end 304 facing the lid and the outward-facing ends 304, 306. The vent block 302 includes a longitudinal hole 318 that opens at the end 304 facing the lid. The longitudinal hole 318 terminates within the vent block 302. The longitudinal hole 318 has threads and engages corresponding threads of the first end 381 of the first fitting 380, as discussed further below.

[0157] The vent block 302 includes a first transverse hole 322 that is perpendicular to and intersects the longitudinal hole 318. The first transverse hole 322 opens on opposite first and third sides 308, 312 of the vent block 302. The opening 324 of the first transverse hole 322 on the first side 308 of the vent block is closed by a one-way valve 336. When closed, the one-way valve 336 is impermeable to air and liquid. The one-way valve 336 opens at a predetermined pressure to allow fluid (e.g., air) to be released from the pressure management system 300. In one example, the one-way valve can be an umbrella valve. The opening 326 of the first transverse hole 322 on the third side 312 of the vent block is closed by a fluid-impermeable first plug 333.

[0158] The vent block 302 includes a second transverse hole 328 that is perpendicular to and intersects the longitudinal hole 318 and the first transverse hole 322. The second transverse hole 328 opens on opposite second and fourth sides 310, 314 of the vent block 302. The opening 332 of the second transverse hole 328 on the second side 310 of the vent block is closed by a breathable membrane 338. The breathable membrane 338 allows air to pass through but prevents liquid from passing through. In one example, the breathable membrane 338 can be a polytetrafluoroethylene (PTFE) membrane. The opening 334 of the second transverse hole 328 on the fourth side 314 of the vent block is closed by a fluid-impermeable second plug 335.

[0159] The longitudinal hole 318 and the first and second transverse holes 322, 328 together define an internal space 316 within the vent block 302.

[0160] A cap 339 having a generally cup-shaped form covers the outward-facing end 306 and the side surfaces 308, 310, 312, 314 of the vent block. The cap 339 is fixed to the outward-facing end 306 of the vent block via fasteners. The cap 339 is spaced apart from the side surfaces 308, 310, 312, 314 of the vent block to ensure good ventilation while protecting the one-way valve 336 and the breathable membrane 338 from debris and / or damage.

[0161] Reference Figure 65 and Figure 66 The main fitting 380 provides fluid communication between the internal space 316 of the ventilation block 302 and the first internal space 358(1) defined by the first bladder 340(1). In addition, the main fitting 380 provides fluid communication between the first internal space 358(1) and the second internal space 358(2) defined by the second bladder 340(2). The secondary fitting 480 provides fluid communication between the second internal space 358(2) and the third internal space 358(3) defined by the third bladder 340(3). The main and secondary fittings 380, 480 will now be described in detail.

[0162] The main fitting 380 provides fluid communication between the internal space 316 of the ventilation block, the internal space 358(1) of the first bladder 340(1), and the internal space 358(2) of the second bladder 340(2). The main fitting 380 is a bar-shaped tube that includes a first open end 381 connected to the ventilation block 302 and a second open end 382 opposite the first end 381 and disposed within the second bladder 340(2). The first end 381 of the main fitting has an external thread that threadedly engages a corresponding thread of the longitudinal hole 318 of the ventilation block. The main fitting 380 includes a side wall 387 extending between the first and second ends 381, 382. The inner surface of the side wall 387 provides a longitudinal fluid passage 388. The longitudinal fluid passage 388 extends between the first and second ends 381 of the main fitting 380 and thus provides fluid communication between the internal space 316 of the ventilation block 302 and the second internal space 358(2). The main fitting 380 includes a first transverse fluid passage 400 that is perpendicular to the longitudinal fluid passage 388, intersects the longitudinal fluid passage 388, and opens at a first side wall opening 452(1) on opposite sides of the side wall 387. In addition, the main fitting 380 includes a second transverse fluid passage 450 that is perpendicular to the longitudinal fluid passage 388 and the first transverse fluid passage 400. The second transverse fluid passage 450 intersects the longitudinal fluid passage 388 and the first transverse fluid passage 400 and opens at a second side wall opening 452(2) on opposite sides of the side wall 387. In use, the main fitting 380 extends through the first bladder 340(1), where the first and second side wall openings 452(1), 452(2) are disposed within the first internal space 358(1). The first and second transverse fluid passages 400, 450 provide fluid communication between the internal space 316 of the ventilation block 302 and the first internal space 358(1).

[0163] The main fitting 380 includes a first portion 440 disposed between the first and second sidewall openings 452(1), 452(2) and the first end 381 of the main fitting 380. The first portion 440 corresponds to the position where the main fitting 380 is fluid-sealed to the first opening 351 of the bladder. The first portion 440 includes a first flange 402 disposed in the first internal space 358(1) and facing the inner surface of the first sheet 341, and a first threaded portion 403 (threads not shown) that projects through the first opening 351. In addition, the first portion 440 includes a first sealing assembly 404 that fixes the first sheet 341 to the first flange 402 in a fluid-impermeable seal. The first sealing assembly 404 includes an elastic flat washer-shaped gasket 406, a flat washer 408, and a nut 410. The gasket 406 is disposed between the first sheet 341 and the first flange 402. The nut 410 engages the first threaded portion 403 and secures the flat washer 408 relative to the outward-facing surface of the first sheet 341, whereby the first sheet 341 and the gasket 406 are clamped between the first flange 402 and the nut 410.

[0164] The first portion 440 has a diameter greater than the diameter of the first end 381 of the main fitting, whereby a shoulder 384 is provided at the transition between the two diameters. In use, the main fitting 380 is disposed in the battery pack housing 2, and the first end 381 projects through an opening in the battery pack housing lid 6. The first end 381 is received within the longitudinal bore 318 of the vent block and engages the threads of the longitudinal bore of the vent block such that the shoulder 384 engages the inner surface of the lid 6 via an intervening gasket. Thus, the main fitting 380 and the vent block 302 cooperate to secure the main fitting 380 and the vent block 302 to the battery pack housing 2.

[0165] In addition, the main fitting 380 includes a second portion 442 disposed between the first sidewall opening and the second sidewall openings 452(1), 452(2) and the second end 382 of the main fitting 380. The second portion 442 corresponds to the position where the main fitting 380 is fluid-sealed to the second opening 352 of the bladder. The second portion 442 includes a second flange 412 disposed in the first internal space 358(1) and facing the inner surface of the second sheet 342, and a second threaded portion 413 (threads not shown) protruding through the second opening 352. In addition, the second portion 442 includes a second sealing assembly 414 that fixes the second sheet 342 to the second flange 412 in a fluid-impermeable seal. The second sealing assembly 414 is substantially similar to the first sealing assembly 404, and the same elements are denoted by the same reference numerals. In the second sealing assembly 414, a gasket 406 is disposed between the second sheet 342 and the second flange 412. In addition, a nut 410 engages the second threaded portion 413 and fixes the flat washer 408 against the outward-facing surface of the second sheet 342, whereby the second sheet 342 and the gasket 406 are clamped between the second flange 402 and the nut 410.

[0166] The main fitting includes a third portion 466 disposed between the second portion 442 and the second end 382 of the main fitting. The third portion 466 includes a shank 468 extending between the second portion 442 and the second end 382 of the main fitting, and a collar 463 surrounding the shank 468. The shank 468 has no external threads and includes a pair of O-ring seals 461, 462( Figure 61 , Figure 64)。Each sealing ring 461, 462 is arranged in the annular grooves 467, 469 to project outwardly relative to the surface of the handle portion 468. The sealing rings 461, 462 are longitudinally spaced apart. The collar 463 has an inner surface 464 that has no internal threads and engages the handle portion 468 by a sliding fit connection in which the sealing rings 461, 462 are compressed. Thus, the connection between the collar 463 and the handle portion 468 is also fluid-impermeable. The collar 463 has a threaded outer surface (threads not shown). In addition, the collar 463 has a distal end 465 that covers the second end 382 of the main fitting. The distal end 465 of the collar includes a third flange 422. The third flange 422 is arranged in the second internal space 358(2) and faces the inner surface of the third sheet 343, and the threaded portion of the collar 463 projects through the third opening 353 (e.g., the opening at the proximal end of the second bladder 340(2)). In addition, the third portion 466 includes a third sealing assembly 424 that fixes the third sheet 343 to the third flange 422 in a fluid-impermeable seal. The third sealing assembly 424 is substantially similar to the first sealing assembly 404, and the same elements are denoted by the same reference numerals. In the third sealing assembly 424, a gasket 406 is arranged between the third sheet 343 and the third flange 422. In addition, a nut 410 engages the threaded outer surface of the collar 463 and fixes the flat washer 408 relative to the outward-facing surface of the third sheet 343, whereby the third sheet 343 and the gasket 406 are clamped between the third flange 422 and the nut 410. In this configuration, the second end 382 of the main fitting is arranged in the internal space 382 of the second bladder 340(2), whereby the internal space 382 of the second bladder 340(2) is in fluid communication with the venting block 302 via the longitudinal fluid passage 388.

[0167] Reference Figure 55 , Figure 56 and Figure 60 , the secondary fitting 480 includes a flexible tube extending between a fourth opening 354 and a fifth opening 355, wherein the fourth opening 354 is an opening at the distal end of the second bladder 340(2) and the fifth opening 355 is an opening at the proximal end of the third bladder 340(3). Each of the opposite ends 481, 482 of the secondary fitting 480 includes a flat-shaped connector 483 that is mechanically connected to a mating flat-shaped connector, the mating flat-shaped connector being provided in each of the fourth opening and the fifth opening 354, 355. The connectors 483, 484 mechanically engage and provide a fluid-impermeable connection.

[0168] As described above, the bladders 340(1), 340(2), 340(3) are flexible so as to expand or contract to accommodate changes in fluid volume caused by pressure and temperature conditions around the battery pack housing 2. When expanding or contracting, the bladders 340(1), 340(2), 340(3) move relative to the inner surface of the battery pack housing 2, the cartridge 20, and other auxiliary components disposed within the battery pack housing 2. In some embodiments, the bladders 340(1), 340(2), 340(3) are provided with a fluid-permeable protective structure to reduce damage to the bladders when the bladders 340(1), 340(2), 340(3) expand and contract within the battery pack housing 2. For example, the battery pack 1 may include a protective mesh sheet 830( Figure 56 ) disposed between the first bladder 340(1) and the cartridge 20. In another example, the battery pack 1 may include a support shell 800( Figure 60 ) surrounding one or more of the bladders 340(1), 340(2), 340(3). In the illustrated embodiment, the support shell 800 is used to protect the second and third bladders 340(2), 340(3).

[0169] Each support shell 800 includes a first half-shell 801 and a second half-shell 802 separable from the first half-shell 801. In cross-section, each of the first half-shell 801 and the second half-shell 802 is generally U-shaped. The first half-shell 801 and the second half-shell 802 open towards each other, and the open end 803 of the second half-shell 802 is partially disposed within the open end 804 of the first half-shell 801. In this way, the first half-shell 801 and the second half-shell 802 cooperate to form a segmented hollow structure, wherein the first half-shell 801 is movable freely relative to the second half-shell 802. That is to say, although the second half-shell 802 is partially disposed within the first half-shell 801, the first half-shell and the second half-shell 801, 802 are only loosely engaged and not fixed to each other. In this way, the support shell 800 is fluid-permeable to facilitate complete exposure of the bladders 340(2), 340(3) to the engineering fluid filling the battery pack housing 2.

[0170] The first half-shell and the second half-shell 801, 802 include openings or cuts 806 allowing the fittings 380, 480 to pass therethrough.

[0171] In the illustrated embodiment, the pressure compensation device 330 is a set of bladders 340 connected in series. However, the pressure compensation device 330 is not limited to a set of bladders 340 connected in series. For example, in some embodiments, the pressure compensation device 330 may be a single bladder. The number of bladders used, as well as the shape and size of the bladders used, are determined by the requirements of the specific application. In addition, the pressure compensation device 330 is not limited to being a flexible, expandable bladder 340. In other embodiments, the bladder 340 may be replaced by one or more pistons or other suitable devices.

[0172] Although the battery pack 1 has been described above as being configured to provide relatively high voltage power to a vehicle powertrain, the battery pack 1 is not limited to high voltage applications. For example, the battery pack 1 can be employed in low voltage applications, such as by reducing the number of battery modules and / or the number of batteries within a module. In another example, the battery pack 1 can be used to provide power to devices other than vehicles, such as environmental control devices and the like.

[0173] Although the positive electrode 218 has been described herein as being electrically connected to the lid portion 205 and the negative electrode 220 as being electrically connected to the container portion 204, it should be understood that the battery 200 can alternatively be configured such that the positive electrode 218 is electrically connected to the container portion 204 while the negative electrode 220 is electrically connected to the lid portion 205.

[0174] In the battery module 40 described above, the positive terminal 214 of each battery 200 is connected to the α portion 140 of one bus bar assembly by a first electrical connector 160(1), and the negative terminal 216 of the battery 200 is connected to the α portion 140 of another bus bar assembly via a second electrical connector 160(2). In the battery module 40, the battery 200 is configured such that the positive terminal 214 of the battery corresponds to the lid portion 205 of the battery and the negative terminal 216 of the battery corresponds to the container portion 204 of the battery. However, it should be understood that the battery 200 is not limited to this configuration. For example, in some embodiments, the battery of an alternative embodiment is configured such that the positive terminal 214 of the battery corresponds to the container portion 204 of the battery and the negative terminal 216 of the battery corresponds to the lid portion 205 of the battery. In a battery module including the battery of the alternative embodiment, the first electrical connector and the second electrical connectors 160(1), 160(2) can be configured such that the current-carrying capacity of the first electrical connector 160(1) is greater than the current-carrying capacity of the second electrical connector 160(2).

[0175] Although the current-carrying capacities of the electrical connectors 160(1), 160(2) are asymmetric in the above-described embodiment, the battery module 40 is not limited to this configuration. For example, in other embodiments, the current-carrying capacity of the first electrical connector 160(1) is the same as the current-carrying capacity of the second electrical connector 160(2), such as the current-carrying capacities of the electrical connectors 160(1), 160(2) are symmetric.

[0176] Selective illustrative embodiments of the battery module and the current collector have been described in detail above. It should be understood that only the structures considered necessary for elucidating the battery module and the current collector have been described herein. Other conventional structures, as well as the structures of accessory and auxiliary members of the battery module and the current collector, are assumed to be known and understood by those skilled in the art. Further, although working examples of the battery module and the current collector have been described above, the battery module and the current collector are not limited to the above working examples, but various design changes can be made without departing from the device as described in the claims.

Claims

1. A battery pack, comprising: A battery pack housing, said battery pack housing including a container and a lid, said lid closing the open end of the container and being joined to the open end of the container via a fluid-impermeable seal; A battery module disposed in said battery pack housing, said battery module including a module housing and electrochemical cells disposed in said module housing; And A vent block disposed on said lid, said vent block including: An internal space, A longitudinal hole extending between the outside of said vent block and said internal space, said longitudinal hole being in fluid communication with the internal space of said battery pack housing, A first transverse hole extending between the outside of said vent block and said internal space, said first transverse hole including a check valve that is normally closed and opens at a predetermined fluid pressure to allow air release, and A second transverse hole extending between the outside of said vent block and the internal space, said second transverse hole including a breathable membrane that is impermeable to liquid but permeable to air, A pressure compensation device disposed in said battery pack housing, said pressure compensation device including an internal space; and A main fitting connecting said vent block to said pressure compensation device, said main fitting including: A first end connected to said longitudinal hole; A second end opposite to said first end; A side wall extending between said first end and said second end, said side wall having an inner surface defining a longitudinal fluid passage extending between said first end and said second end; and A transverse fluid passage extending between an opening in said side wall and said longitudinal fluid passage, the internal space of said pressure compensation device being in fluid communication with the internal space of said vent block via said transverse fluid passage and said longitudinal fluid passage, Wherein, Said battery pack housing is filled with a dielectric fluid.

2. The battery pack according to claim 1, wherein, Said vent block is disposed on the outer surface of said lid, The first end of the main fitting protrudes through the lid and engages with the longitudinal hole of said vent block, and Said longitudinal fluid passage provides fluid communication between the internal space of said vent block and the inside of said battery pack housing.

3. The battery pack according to claim 1, wherein, Said breathable membrane includes a polytetrafluoroethylene membrane.

4. The battery pack according to claim 1, wherein Said check valve includes an umbrella valve.

5. The battery pack according to claim 1, wherein, Said vent block includes a cap that covers said check valve and said breathable membrane and is spaced apart from said check valve and said breathable membrane.

6. The battery pack according to claim 1, wherein, Said first transverse hole and said second transverse hole intersect.

7. The battery pack according to claim 1, wherein Said longitudinal hole is perpendicular to the outer surface of the lid, and said first transverse hole and said second transverse hole are perpendicular to said longitudinal hole.

8. The battery pack according to claim 1, wherein, The main fitting is configured to be able to fix said vent block to the lid.

9. The battery pack according to claim 1, wherein, Said main fitting includes: A first flange protruding outward from the outer surface of said side wall, said first flange being disposed between said opening and said first end; and A second flange protruding outward from the outer surface of said side wall, said second flange being disposed between said opening and said second end, wherein, A first part of said main fitting extends through a first opening in said pressure compensation device, and a first sealing assembly provides a fluid seal between the first opening in said pressure compensation device and said first flange; and The second part of the main fitting extends through the second opening in the pressure compensation device, and a second sealing assembly provides a fluid seal between the second opening in the pressure compensation device and the second flange.

10. The battery pack according to claim 9, wherein, The first sealing assembly and the second sealing assembly include an elastic gasket, a rigid washer, and a nut.

11. The battery pack according to claim 1, wherein, The pressure compensation device includes a first wall portion covering a second wall portion, and wherein the main fitting extends through the openings in the first wall portion and the second wall portion such that: The first end is disposed outside the pressure compensation device on a side of the pressure compensation device corresponding to the first wall portion, and the first end is disposed in a longitudinal hole; The second end is disposed outside the pressure compensation device on a side of the pressure compensation device corresponding to the second wall portion; and The opening in the side wall is disposed in the internal space of the pressure compensation device.

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