Pressure management device for a battery pack

Abstract

A battery pack includes a battery pack housing having a lid joined to an open end via a fluid-impermeable seal. The battery pack further includes a battery module disposed within the battery pack housing and including a plurality of electrochemical cells. Additionally, the battery pack includes a pressure compensation device located within the battery pack housing, the pressure compensation device including a first bladder fluidly coupled to a second bladder via a main fitting. The battery pack housing is filled with a dielectric fluid. Additionally, the pressure compensation device includes a second fluid.

Description

Technical Field

[0001] Battery packs power a variety of technologies, 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 multiple 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 manufacture 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. Further, when the current collectors are arranged at each opposite end of the battery, cooling the battery 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 can 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 ordered 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, a battery pack includes a battery pack housing having a lid joined to an open end via a fluid-impermeable seal. The battery pack further includes a battery module disposed within the battery pack housing and including a plurality of electrochemical cells. Additionally, the battery pack includes a pressure compensation device located within the battery pack housing, the pressure compensation device including a first bladder fluidly coupled to a second bladder via a main fitting. The battery pack housing is filled with a dielectric fluid. Further, the pressure compensation device includes a second fluid.

[0005] In other aspects, the battery pack includes a battery pack housing having a lid joined to an open end via a fluid-impermeable seal. The battery pack further includes a cartridge disposed within the battery pack housing, the cartridge including at least a pair of battery modules, where each battery module includes a plurality of electrochemical cells. Additionally, the battery pack includes a pressure compensation device located within the battery pack housing, the pressure compensation device including: (i) a first bladder at least partially located between the lid and the cartridge, (ii) a second bladder fluid-coupled to the first bladder via a primary fitting and at least partially disposed around the cartridge, and (iii) a third bladder fluid-coupled to the second bladder via a secondary fitting. The battery pack housing is filled with a dielectric fluid. The pressure compensation device includes a second fluid. Additionally, the primary fitting projects through the lid of the battery pack housing and is coupled to a vent block having a hole located outside the battery pack housing. Additionally, the hole opens at a predetermined fluid pressure, and the battery pack further includes a third bladder fluid-coupled to the second bladder via a secondary fitting.

[0006] In some embodiments, the second fluid is air.

[0007] In some embodiments, the bladder housing includes a pair of sheets, each sheet of the pair including a metal and polymer laminate. The pair of sheets are joined to each other along a fluid-tight seal line, and the interior space of the bladder is defined by each sheet of the pair and the seal line.

[0008] In some embodiments, the bladder housing is capable of conforming to the shape of the module housing and other auxiliary structures disposed within the battery pack housing.

[0009] In some embodiments, the bladder is at least partially enclosed within a fluid-permeable support shell.

[0010] In some embodiments, the support shell includes a first portion and a second portion separable from the first portion, the first portion and the second portion cooperating to form a segmented hollow structure, and the bladder is disposed within the structure.

[0011] In some embodiments, the support shell includes a first half-shell having a U-shape and a second half-shell having a U-shape, the second half-shell being partially disposed within the first half-shell, and the second half-shell being capable of moving freely relative to the first half-shell.

[0012] In some embodiments, the main fitting is partially disposed within the bladder. The main fitting includes: a first end of the main fitting that protrudes through a sealed opening in the bladder; a second end of the main fitting opposite the first end of the main fitting; and a sidewall of the main fitting that extends between the first end of the main fitting and the second end of the main fitting. An inner surface of the sidewall of the main fitting provides a main fitting fluid passage, whereby the main fitting fluid passage extends between the first end of the main fitting and the second end of the main fitting. The main fitting includes an opening in the sidewall of the main fitting. The opening provides a lateral fluid passage that permits fluid communication between the main fitting fluid passage and an interior space of the bladder.

[0013] In some embodiments, the bladder includes a first bladder disposed between a surface of the module housing facing the lid and the lid, and a second bladder disposed between the first bladder and the container. The second end of the main fitting is disposed within the second bladder, and the main fitting provides fluid communication between the second bladder and the vent block.

[0014] In some embodiments, the battery module includes a first battery module and a second battery module. The first battery module includes a first module housing and a first set of electrochemical cells disposed within the first module housing. The second battery module includes a second module housing and a second set of electrochemical cells disposed within the second module housing. Additionally, the bladder includes a first bladder and a second bladder. The first bladder is disposed between the lid and the first module housing and the second module housing, and the second bladder is disposed between the first module housing and the second module housing. Additionally, the second bladder is in fluid communication with the first bladder.

[0015] In some embodiments, the bladder includes a third bladder, and the second bladder and the third bladder are connected by a secondary fitting that provides fluid communication between an interior space of the second bladder and an interior space of the third bladder.

[0016] In some embodiments, the main fitting provides fluid communication between the interior spaces of the first bladder, the second bladder, and the vent block.

[0017] In some embodiments, the vent block is disposed on an outer surface of the lid, and the main fitting is configured to be able to secure the vent block to the lid.

[0018] In some embodiments, the first vent hole includes a polytetrafluoroethylene membrane.

[0019] In some embodiments, the second vent hole includes an umbrella valve.

[0020] In some embodiments, the first fluid is non-flammable.

[0021] In some embodiments, a mesh is disposed between the bladder and the housing of the battery module.

[0022] In some embodiments, the bladder includes a bladder outer periphery and a sealed through-hole at a position spaced apart from and surrounded by the bladder outer periphery.

[0023] Each battery module includes a busbar assembly that provides electrical connection of battery terminals within the battery module. Each busbar assembly includes a substrate and an insulating layer attached to the battery-facing surface of the substrate. The insulating layer is electrically insulating, thermally insulating, and 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. When the battery expands and contracts within the module, the insulating layer can prevent short circuits. Additionally, the insulating layer is flame retardant, so it can maintain its electrical and thermal isolation properties in the event of a thermal runaway of the battery.

[0024] In a battery module, the positive terminal of each battery is connected to one busbar assembly via a first electrical connector, and the negative terminal of the battery is connected to another busbar 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 with the current-carrying capacity of the first electrical connector less than that of the second electrical connector, the electrical connection to the positive terminal of each battery fails prior to 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.

[0025] The battery pack includes a plurality of battery modules, and the battery modules are bundled in a sub-assembly called a cartridge. The cartridge is disposed within the 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.

[0026] Since the battery pack is filled with the engineering fluid, the battery modules and the battery cartridge do not include fluid-sealing features to facilitate active cooling. Thus, compared to the active thermal management systems of some conventional battery packs, the components of the battery modules, the cartridge, and the thermal management system are simplified, and thus manufacturing is easier and less costly.

[0027] 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, allowing an increase in the flow rate of the cooling fluid 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 individually controlled, and the overall temperature of the battery pack can be balanced. Description of the Drawings

[0028] Figure 1 is a side view of the battery pack;

[0029] Figure 2 is Figure 1 a perspective view of the battery pack of , in which the lid and some auxiliary structures are omitted to illustrate the arrangement of the cartridge within the battery pack housing;

[0030] Figure 3 is a perspective view of the cartridge;

[0031] Figure 4 is a perspective view of the cartridge, in which the fluid inlet header assembly and the outlet header assembly are omitted to show the battery modules arranged within the cartridge;

[0032] Figure 5 is a perspective view of the cartridge housing with the battery modules omitted;

[0033] Figure 6 is a perspective view of the battery module;

[0034] Figure 7 is along Figure 6 the 7-7 line of to see the cross-sectional view of the battery module;

[0035] Figure 8 is an exploded perspective view of the battery module;

[0036] Figure 9 is a partially exploded perspective view of the electrochemical cell;

[0037] Figure 10 is a schematic diagram of the arrangement of the batteries in the battery module;

[0038] Figure 11 is a side view of the battery array within the battery module, showing the arrangement of the batteries in the quadrants;

[0039] Figure 12 is a perspective view of a separate frame;

[0040] Figure 13 is a perspective view of a frame including the batteries;

[0041] Figure 14 is a perspective view of a separate bus bar assembly seen from the first side of the battery module;

[0042] Figure 15 is a perspective view of the first to third bus bar assemblies;

[0043] Figure 16 is a perspective view of the second bus bar assembly;

[0044] Figure 17 is a perspective view of the first bus bar assembly;

[0045] Figure 18 is a perspective view of the third bus bar assembly;

[0046] Figure 19 is a perspective view of the fourth and fifth bus bar assemblies;

[0047] Figure 20 is a perspective view of a separate bus bar assembly as seen from the second side of the battery module;

[0048] Figure 21 is along Figure 15 an end view of the first to third bus bar assemblies as seen in the direction of arrow A in;

[0049] Figure 22 is a perspective view of the first bus bar assembly;

[0050] Figure 23 is an exploded view of the first bus bar assembly;

[0051] Figure 24 is a perspective view of the fifth bus bar assembly;

[0052] Figure 25 is an exploded view of the fifth bus bar assembly;

[0053] Figure 26 is Figure 29 a detailed view of a cross-sectional view of the battery module shown by the dashed line in;

[0054] 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;

[0055] 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;

[0056] Figure 29 is a cross-sectional view of the battery module with the spacer omitted;

[0057] Figure 30 is a cross-sectional view of the battery module including the spacer;

[0058] Figure 31 is a perspective view of a separate spacer;

[0059] Figure 32 is an end view of a separate spacer;

[0060] Figure 33 is Figure 30 a detailed view of a cross-sectional view of the battery module shown by the dashed line in

[0061] Figure 34 is an exploded perspective view of the box;

[0062] Figure 35 is an exploded view of the battery module and the separator of the box;

[0063] Figure 36 is a top view of the battery pack housing, where the lid and auxiliary structures are omitted to show the thermal management system, and a pump is schematically shown therein;

[0064] Figure 37 is a perspective view of a separate fluid delivery part of the thermal management system;

[0065] 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;

[0066] Figure 39 is a perspective view of a separate fluid return part of the thermal management system;

[0067] 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;

[0068] Figure 41 is an exploded perspective view of the box, where the box housing is omitted and the inlet gas collection assembly is shown;

[0069] Figure 42 is a perspective view of a part of the box, showing the inlet gas collection assembly;

[0070] Figure 43 is a perspective view of a part of the box, showing the inlet gas collection assembly including a manifold part with an inlet opening connected to the inlet gas collection assembly;

[0071] Figure 44 is along Figure 42 the cross-sectional view of the inlet gas collection assembly seen along line 44-44;

[0072] Figure 45 is along Figure 42 the cross-sectional view of the inlet gas collection assembly seen along line 45-45;

[0073] Figure 46 is along Figure 42Cross-sectional view of the inlet air collection assembly as seen along line 46-46;

[0074] Figure 47 Perspective view of the module-facing surface of the inlet air collection assembly;

[0075] Figure 48 Is Figure 47 Exploded perspective view of the inlet air collection assembly;

[0076] Figure 49 Exploded perspective view of the box, where the box housing is omitted and the outlet air collection assembly is shown;

[0077] Figure 50 Perspective view of a part of the box, showing the outlet air collection assembly;

[0078] Figure 51 Perspective view of a part of the box, showing the outlet air collection assembly including a fluid return branch line with an outlet opening connected to the outlet air collection assembly;

[0079] Figure 52 Is Figure 51 Magnified perspective view;

[0080] Figure 53 Perspective view of the module-facing surface of the outlet air collection assembly;

[0081] Figure 54 Is Figure 53 Exploded perspective view of the outlet air collection assembly;

[0082] Figure 55 Side view of a separate pressure management system;

[0083] 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;

[0084] Figure 57 End view of a separate pressure management system;

[0085] Figure 58 Top perspective view of the first bladder;

[0086] Figure 59 Is along Figure 58 Cross-sectional view of the first bladder as seen along line 59-59;

[0087] Figure 60 Exploded perspective view of the second and third bladders and the protective shell;

[0088] Figure 61 Cross-sectional view of a part of the battery pack, showing details of the main fitting and the vent block;

[0089] Figure 62 is a cross-sectional view of the ventilation block;

[0090] Figure 63 and Figure 64 are additional cross-sectional views of a portion of the battery pack, showing details of the main fitting and the ventilation block;

[0091] Figure 65 is an exploded view of the main fitting;

[0092] Figure 66 is a cross-sectional view of a portion of the main fitting. DETAILED DESCRIPTION

[0093] Referring to Figure 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 100 V. For example, in some embodiments, the battery pack 1 can operate at 400 V, while in other embodiments, the battery pack 1 can operate at 800 V. 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" means having a height hp that is small relative to a length lp and a 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.

[0094] The battery pack housing 2 is filled (e.g., completely filled, filled to overflow) with an engineered fluid and is sealed to prevent leakage and / or evaporation of the engineered fluid. The engineered fluid has dielectric properties, non-flammability, and chemical inertness. For example, the fluid can be ethoxy-nonafluorobutane, such as Novec TM 7200 manufactured by 3M Company of 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 adapt to changes in ambient temperature and pressure, as discussed in detail below.

[0095] In some embodiments, the battery pack 1 may 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.

[0096] Each of the battery modules 40(1), 40(2), 40(3) of a given cartridge 20 may 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 requirements of the particular application, the electrical connections may be in parallel, series, or a combination of parallel and series.

[0097] Referring Figure 8 to

[0098] Referring Figure 9-10 and Figure 13, the battery 200 is a cylindrical lithium-ion battery. Each battery 200 includes a cylindrical battery housing 203 having a container portion 204 and a lid portion 205 that closes the open end of the container portion 204. The lid portion 205 is disposed on the first end 207 of the battery 200 and seals the container portion 204 through an electrically insulating gasket 206. The container portion 204 includes a closed end disposed at the second end 208 of the battery housing 203, and the second end 208 is opposite to the first end 207 of the battery that includes the lid portion 205. The container portion 204 includes a battery housing sidewall 210 that projects from the closed end 208 and is perpendicular to the closed end 208. The container portion 204 extends along the longitudinal axis 212 of the battery that extends between the first end 207 and the second end 208 of the battery. That is, the longitudinal axis 212 extends parallel to the battery housing sidewall 210. Each battery 200 has the same shape and size, including a battery diameter d1.

[0099] The electrode assembly 226 and the electrolyte are sealed within the battery housing 203 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, and the lid portion 205 serves as the positive terminal 214 of the battery 200. Additionally, the other electrode, such as the negative electrode 220, is electrically connected to the container portion 204, and the container portion 204 serves as the negative terminal 216 of the battery 200.

[0100] Due to the curved shape of the battery, the cylindrical battery 200 may have a lower packaging efficiency in a battery module than some other battery types. To maximize the packaging efficiency of the cylindrical battery 200, the batteries 200 are stored in the battery module 40 in a "close-packed" configuration. As used herein, the term "close-packed" refers to a configuration in which the batteries 200 are arranged in rows and columns. Additionally, when the battery 200 is viewed in an end view ( Figure 9) The alternating rows are relatively offset in a direction parallel to the row such that the center 228 of the cells 200 in one row is between the centers 228 of the cells 200 in the adjacent row. Additionally, each cell 200 is in direct contact with adjacent cells within its own row (i.e., 200(1), 200(2)) and with adjacent cells in adjacent rows (i.e., 200(3), 200(4), 200(5), 200(6)). Sometimes, this cell configuration is also referred to as a "hexagonal packing" configuration. In the illustrated embodiment, the array 202 includes 8 rows of cells 200, and each row includes 38 cells. In other embodiments, depending on the needs of the particular application, the array 202 may include more or fewer rows and / or more or fewer cells 200 per row. The cells 200 in the array 202 are aligned such that when the cells 200 are viewed in a side view, the ends 207 or 208 of each cell 200 are disposed in a first plane P1 ( Figure 13 ), which is common to each cell 200 in the array 202.

[0101] Referring Figure 11 , within the array 202, the cells 200 are grouped in quadrants Q1, Q2, Q3, Q4, and all the cells 200 in a given quadrant have the same orientation such that terminals of the same polarity are disposed on the same side of the given quadrant. Additionally, when the array 202 is viewed in a direction facing the cell ends 207, 208, the cells 200 in adjacent quadrants have opposite polarities. For example, as Figure 10 shown, one side of the array 202 is illustrated, whereby the cells 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 cells 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 the cell 200 is visible. Additionally, the cells 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 the cell 200 is visible. By grouping the cells 200 in quadrants Q1, Q2, Q3, Q4, the electrical connections between the cells 200 in the array 202 provided via the bus bars 130 are simplified.

[0102] Referring Figure 12 and Figure 13, the frame 50 holds the batteries 200 in a closely packed arrangement. The frame 50 includes a cover plate 52, a bottom plate 54, a first end cap 56 that connects the first end of the cover plate 52 to the first end of the bottom plate 54, and a second end cap 58 that connects the second end of the cover plate 52 to the second end of the bottom plate 54. Additionally, the 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 battery 200, where the length lc of the battery 200 is the distance between the first end 207 (e.g., the lid portion 205) and the enclosed second end 208. The cover plate 52 and the bottom plate 54 have a length that accommodates the length la of the battery array 202, which in turn corresponds to the size of the rows of the batteries 200. Additionally, the first and second end caps 56, 58 and the central wall 60 are sized to accommodate the height ha of the battery array 202.

[0103] The frame 50 surrounds the perimeter of the battery array 202 and covers the side walls 210 of each battery in the array 202. In other words, the batteries 200 are oriented such that the longitudinal axis 212 of each battery 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 batteries and thus the battery positive and negative terminals 214, 216 of each battery 200 are exposed at the respective open sides 72, 74 of the frame 50.

[0104] The profiles of the battery-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 battery side walls 210 of the outermost batteries 200 of the array 202. For example, the battery-facing surfaces 62, 64, 66, 68, 70 may have a wavy profile that receives and supports the outermost batteries of the array 202. In some embodiments, to further secure and hold the batteries 200 in the desired closely packed configuration, an adhesive may be used to fasten the battery housing 203 of a given battery 200 to the battery housing 203 of each adjacent battery 200.

[0105] 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).

[0106] Reference Figure 8 and Figure 14-21 , the bus bar 130 provides battery terminal interconnections within the battery module 40. The bus bar 130 includes five bus bar assemblies 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 assembly 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 the batteries 200 corresponds to the batteries 200 within the first quadrant Q1. In addition, the first bus bar assembly 130(1) serially connects the batteries 200 of the first quadrant Q1 to the negative terminal 44 of the battery module.

[0107] The second bus bar assembly 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 the batteries 200 corresponds to the batteries 200 within the second quadrant Q2. In addition, the second bus bar assembly 130(2) serially connects the batteries 200 of the second quadrant Q2 to the positive terminal 42 of the battery module.

[0108] The third bus bar assembly 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 the batteries 200 corresponds to the batteries 200 within the third quadrant Q3. In addition, the third bus bar assembly 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 the batteries 200 corresponds to the batteries 200 within the fourth quadrant Q4. In addition, the third bus bar assembly 130(3) serially connects the batteries 200 of the third quadrant Q3 to the batteries 200 of the fourth quadrant Q4.

[0109] 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. Additionally, 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.

[0110] 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. Additionally, 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.

[0111] 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 battery terminal facing side 132 of the substrate 138, and an electrical connector 160 providing an electrical connection between the substrate 138 and each respective battery terminal 214 or 216.

[0112] The substrate 138 is a rigid, conductive thin plate. The substrate 138 includes a first side 132 facing the battery 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. Additionally, 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 tab 48.

[0113] Each substrate 138 includes an α portion 140 corresponding to the area forming 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 providing a series 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.

[0114] 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 battery array 202. 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 battery 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. Additionally, the second leg of the "L" is perpendicular to the first leg and covers a portion of the frame 50 (e.g., covers the sidewall of the cell 200). The second leg of the "L" corresponds to the β portion 150 of the substrate 138.

[0115] The α portion 140 lies 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, thereby exposing 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 cell 200. The main connection through-holes 142 expose the ends of the cells such 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 bonding wires. The α portion also includes main flow-through holes 144 that are aligned with small gaps between the sidewalls 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.

[0116] The β portion 150 is located in a third plane P3 perpendicular to the second plane P2. In the substrates 138 of the first and second busbar assemblies 130(1) and 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) and 130(2) may be integrally formed with the corresponding terminals 42 and 44, and in other embodiments, the β portions 150 of the first and second busbar assemblies 130(1) and 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 one 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 one edge of the β portion 150 of the second busbar assembly 130(2). Thus, the terminals 42 and 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) and 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.

[0117] In the substrates 138 of the first, second, and third busbar assemblies 130(1), 130(2), and 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. In addition, the β portions 150 of the first, second, and third busbar assemblies 130(1), 130(2), and 130(3) may include bar-shaped openings 152. The openings 152 receive the tabs 55 protruding from the outward-facing surfaces of the frame cover plate and bottom plate 52 and 54, whereby the openings 152 allow for the correct alignment and orientation of the busbar assemblies 130(1), 130(2), and 130(3) relative to the frame 50 and are used to maintain the correct alignment of the busbar assemblies 130(1), 130(2), and 130(3) relative to the frame 50.

[0118] 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 disposed 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.

[0119] Referring Figure 22-26 and Figure 29 , an insulating layer 180 is disposed on the side 132 of the substrate 138 facing the cell 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 cell 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.

[0120] 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 cell 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 short circuits between the substrate 138 and the cell 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.

[0121] 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 secures 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 secures 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.

[0122] Referring to Figure 27-28 , for each of the battery terminals 214, 216, the electrical connector 160 extends between and provides an electrical connection 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). For example, the electrical connector 160 may be a wire bond, but is not limited to this type of electrical connector. As used herein, the term "wire bond" refers to an electrical connector in the form of a fine 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 wire bonding process. Other suitable electrical connectors may be used instead of wire bonds 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).

[0123] In the battery module 40, the positive terminal 214 of each battery 200 is connected to the α portion 140 of a 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 a 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.

[0124] 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.

[0125] 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 with a diameter smaller than that of the second bonding wire.

[0126] 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).

[0127] 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.

[0128] 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, and is 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.

[0129] 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.

[0130] 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 the 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 the 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 cap and the second end cap 56, 58 of the frame are arranged in the open first end and second end 82, 84 of the spacer structure.

[0131] 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 discussed further below. The number of grooves 98 provided in each of the first and second wall portions 86, 90 corresponds to the number of rows of cells 200 in the cell array 202. Each groove 98 is aligned with a row of the cell array 202 and opens towards the cell array 202, whereby the cell 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 cell array 202. For this purpose, the shape and size of the groove 98 are designed to accommodate sufficient coolant fluid flow to maintain the cells 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 cells 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.

[0132] 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 cells including the electrical connectors 160. In some embodiments, the electrical connectors 160 are 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 connectors 160 in the fluid passage 102 is minimized.

[0133] 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 directed through the fluid passage 102 defined by the groove 85, the fluid flow through the battery module 40 is not blocked, including the flow between the side walls 210 of adjacent cells 200 and through the main and secondary flow holes 144, 190 of the bus bar assembly 130 of the battery module 40.

[0134] 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 a one-piece structure (not shown), or for ease of assembly with the frame 50, it can be manufactured as two U-shaped halves 80(1), 80(2).

[0135] 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 which 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.

[0136] 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 an 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 event of battery venting 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.

[0137] The battery modules 40(1), 40(2), 40(3) are prevented from leaving 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.

[0138] 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. Further, at each open end 23 of the cartridge housing 22, the polarities of the three projecting battery module terminals 42, 44 alternate in polarity.

[0139] 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 within 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.

[0140] 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 supply fluid to the inlet plenum assemblies 502 in parallel.

[0141] 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.

[0142] 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 which merge into a fluid return line 692.

[0143] 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 cell 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 cell modules 40(1), 40(2), 40(3).

[0144] The inlet plenum assembly 502 simultaneously distributes fluid to each of the cell 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 spaced structure 80 of each of the cell modules 40(1), 40(2), 40(3), as will now be described.

[0145] 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 of the partitions 110 and are thus configured to receive fluid diverted from the inlet diverter 540 and direct it to the fluid channels 102.

[0146] 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 pair of fluid inlet openings 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.

[0147] 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 within 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 within 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 within the delivery port 688.

[0148] 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).

[0149] 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 into 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., bulging) 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, a fastener such as a screw 522 is used to secure 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 space between the end plate 506 and the diverter 504. The inlet diverter 540 directs the fluid into 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.

[0150] 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 of the battery modules 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. To this end, 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.

[0151] Referring to 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 expansion coefficient 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.

[0152] 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 engineering fluid within the sealed battery pack housing 2, such as those caused by pressure and temperature conditions surrounding 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.

[0153] Each of the bladders 340(1), 340(2), 340(3) is an enclosed bag formed of a material impermeable to gas and moisture that is flexible enough to allow the bladder 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 surface of the cartridge housing 22 disposed within the battery pack housing 2, and other auxiliary structures.

[0154] 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, an intermediate polyethylene terephthalate (PET) film layer, and an inner polypropylene film layer. In another example, the laminate may have three layers, including an outer PET film layer, an intermediate metal foil layer, and an inner polypropylene film layer.

[0155] 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 that 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.

[0156] The first bladder 340(1) is larger than the second and third bladders 340(2), 340(3) and is disposed between the cassette 20 and the lid 6. The first bladder 340(1) can be formed, for example, by laminating a first sheet 341 and a second sheet 342 and sealing the outer periphery 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 material used to form the first bladder 340(1).

[0157] The first bladder 340(1) includes a first opening 351 that is formed in the first sheet 341 at a position spaced 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.

[0158] The first bladder 340(1) includes a second opening 352 that is formed in the second sheet 342 at a position spaced 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 hi. 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.

[0159] In addition, the first bladder 340(1) includes a pair of sealed through-holes 358 at a position spaced from the outer peripheral edge 356 of the bladder. The through-holes 358 allow the auxiliary members of the battery pack 1 to pass through the first bladder 340(1). For example, in the illustrated embodiment, the through-holes 358 allow the filling tube to pass through the first bladder 340(1). In the illustrated embodiment, the through-holes 358 are disposed near the first and second openings 351, 352 such that one through-hole 358 is disposed on each opposite side of the first and second openings 351.

[0160] The second bladder 340(2) is disposed in the gap 9 between two sets of cassettes 20 and is 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.

[0161] 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.

[0162] 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 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.

[0163] 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 outer-facing end 306 opposite the end 304 facing the lid, and four sides 308, 310, 312, 314 extending between the end 304 facing the lid and the outer-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 is threaded and engages with corresponding threads of the first end 381 of the first fitting 380, as discussed further below.

[0164] 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.

[0165] 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.

[0166] The longitudinal hole 318 and the first and second transverse holes 322, 328 together define an internal space 316 within the vent block 302.

[0167] A cap 339 having a generally cup-shaped form covers the outer-facing end 306 and the sides 308, 310, 312, 314 of the vent block. The cap 339 is fixed to the outer-facing end 306 of the vent block via a fastener. The cap 339 is spaced apart from the sides 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.

[0168] 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.

[0169] 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 engages the corresponding thread of the longitudinal hole 318 of the ventilation block. The main fitting 380 includes a side wall 387 that extends between the first and second ends 381, 382. The inner surface of the side wall 387 provides a longitudinal fluid channel 388. The longitudinal fluid channel 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 channel 400 that is perpendicular to the longitudinal fluid channel 388, intersects the longitudinal fluid channel 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 channel 450 that is perpendicular to the longitudinal fluid channel 388 and the first transverse fluid channel 400. The second transverse fluid channel 450 intersects the longitudinal fluid channel 388 and the first transverse fluid channel 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 channels 400, 450 provide fluid communication between the internal space 316 of the ventilation block 302 and the first internal space 358(1).

[0170] 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 fixes 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.

[0171] 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 hole 318 of the vent block and engages the threads of the longitudinal hole 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 fix the main fitting 380 and the vent block 302 to the battery pack housing 2.

[0172] 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 relative to 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.

[0173] 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 shank 468. The sealing rings 461, 462 are longitudinally spaced apart. The collar 463 has an inner surface 464 which has no internal threads and engages the shank 468 by a slip fit connection in which the sealing rings 461, 462 are compressed. Thus, the connection between the collar 463 and the shank 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 disposed 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., an opening at the proximal end of the second bladder 340(2)). In addition, the third portion 466 includes a third sealing assembly 424 which 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, the gasket 406 is disposed between the third sheet 343 and the third flange 422. In addition, the 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 disposed 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 vent block 302 via the longitudinal fluid passage 388.

[0174] 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 disposed in each of the fourth opening and the fifth opening 354, 355. The connectors 483, 484 are mechanically engaged and provide a fluid-impermeable connection.

[0175] 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 due to 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 that reduces 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).

[0176] 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, 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.

[0177] The first half-shell and the second half-shell 801, 802 include openings or cuts 806 that allow the fittings 380, 480 to pass therethrough.

[0178] 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.

[0179] 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.

[0180] 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 and the negative electrode 220 is electrically connected to the lid portion 205.

[0181] In the battery module 40 described above, the positive terminal 214 of each battery 200 is connected to an α portion 140 of a bus bar assembly via a first electrical connector 160(1), and the negative terminal 216 of the battery 200 is connected to an α portion 140 of another bus bar assembly via a second electrical connector 160(2). In the battery module 40, the batteries 200 are 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 batteries of an alternative embodiment are 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 batteries 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).

[0182] 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.

[0183] 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. In addition, 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 having a lid joined to an open end via a fluid-impermeable seal; a battery module disposed within the battery pack housing and including a plurality of electrochemical cells; and a pressure compensation device located within the battery pack housing, the pressure compensation device including a first bladder fluid-coupled via a main fitting to a second bladder, wherein the battery pack housing is filled with a dielectric fluid, and the pressure compensation device includes a second fluid, the main fitting protruding through the lid of the battery pack housing and coupled to a vent block having a hole located outside the battery pack housing, wherein the hole opens at a predetermined fluid pressure.

2. The battery pack according to claim 1, wherein the battery pack further includes a third bladder fluid-coupled via a secondary fitting to the second bladder.

3. The battery pack according to claim 1, wherein the first bladder is at least partially located between the lid and the battery module.

4. The battery pack according to claim 1, wherein the second bladder is disposed around the battery module.

5. The battery pack according to claim 2, wherein at least two of the battery modules are combined together as a cartridge, and the second bladder is disposed around the cartridge.

6. The battery pack according to claim 5, wherein the battery pack includes a first pair of cartridges, and the second bladder is disposed between the cartridges in the first pair of cartridges.

7. The battery pack according to claim 6, wherein the battery pack further includes a second pair of cartridges, and the third bladder is disposed between the cartridges in the second pair of cartridges.

8. The battery pack according to claim 2, wherein at least one of the first bladder, the second bladder, and the third bladder includes a pair of metal and polymer laminates coupled together along a seal line.

9. The battery pack according to claim 8, wherein the pair of metal and polymer laminates are coupled together along the seal line via heating.

10. The battery pack according to claim 2, wherein the secondary fitting includes a flexible tube.

11. The battery pack according to claim 1, wherein the battery pack further includes a protective sheet located between the first bladder and the battery module.

12. The battery pack according to claim 1, wherein at least one of the first bladder and the second bladder includes a fluid-permeable support shell.

13. The battery pack according to claim 12, wherein the support shell includes a first half-shell and a second half-shell located around the corresponding bladder.

14. A battery pack, comprising: a battery pack housing having a lid joined to an open end via a fluid-impermeable seal; a cartridge disposed within the battery pack housing, the cartridge including at least a pair of battery modules, wherein each battery module includes a plurality of electrochemical cells; and a pressure compensation device located within the battery pack housing, the pressure compensation device including: a first bladder at least partially located between the lid and the cartridge, a second bladder fluid-coupled via a main fitting to the first bladder and at least partially disposed around the cartridge, and A third bladder fluidly coupled to the second bladder via a secondary fitting, wherein the battery pack housing is filled with a dielectric fluid, the pressure compensation device includes a second fluid, the primary fitting projects through a lid of the battery pack housing and is coupled to a vent block having a hole located outside the battery pack housing, and wherein, the hole opens at a predetermined fluid pressure.

15. The battery pack according to claim 14, wherein, the battery pack includes a first pair of cartridges, and the second bladder is disposed between the cartridges of the first pair of cartridges.

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