WO2023177646A1

WO2023177646A1 - Expansion systems and methods for battery pack

Info

Publication number: WO2023177646A1
Application number: PCT/US2023/015155
Authority: WO
Inventors: James Banwell; Randy DUNN
Original assignee: Electric Power Systems, Inc.
Priority date: 2022-03-14
Filing date: 2023-03-14
Publication date: 2023-09-21

Abstract

A battery module can comprise: an end plate; a pressure plate spaced apart from the end plate by a distance; an array of pouch cells disposed between the end plate and the pressure plate; and an expansion protection system configured to allow the distance to increase from a first length to a second length in response to charging the array of pouch cells, and/or decrease from a second length to the first length or a third length in response to discharging the array of pouch cells

Description

TITLE: EXPANSION SYSTEMS AND METHODS FOR BATTERY

PACK

INVENTORS: JAMES BANWELL

RANDY DUNN

ASSIGNEE: ELECTRIC POWER SYSTEMS, INC.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims pnonty to, and the benefit of, US Provisional

Patent Application No. 63/319,653, filed on March 14, 2022 and titled “EXPANSION SYSTEMS AND METHODS FOR BATTERY PACK,” which is incorporated by reference herein in its entirety for all purposes.

FIELD OF INVENTION

[0002] The present disclosure generally relates to apparatus, systems and methods for providing battery systems with expansion capability to facilitate alternative battery chemistries

BACKGROUND OF THE INVENTION

[0003] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art The subject matter in the background section merely represents different approaches, which in and of themselves may be inventions.

[0004] A battery module, for purposes of this disclosure, includes a plurality of electrically connected electrochemical or electrostatic cells hereafter referred to collectively as “cells”. These cells may, in turn, include a parallel, series, or combination of both, collection of cells that can be charged electrically to provide a static potential for power or released electrical charge when needed. When cells are assembled into a battery module, the cells are often linked together through metal strips, straps, wires, bus bars, etc., that are welded, soldered, or otherwise fastened to each cell to link them together in the desired configuration. [0005] A cell may be comprised of at least one positive electrode and at least one negative electrode. One common form of such a cell is the well-known secondary cells packaged in a cylindrical metal can or in a prismatic case. Examples of chemistry used in such secondary cells are lithium cobalt oxide, lithium manganese, lithium iron phosphate, nickel cadmium, nickel zinc, and nickel metal hydride. Such cells are mass produced, driven by an ever-increasing consumer market that demands low cost rechargeable energy for portable electronics.

SUMMARY OF THE INVENTION

[0006] Disclosed herein is a battery module having an expansion protection system. The battery module includes a plurality of cells electrically coupled together (e.g., in series and/or in parallel). The battery module is configured to facilitate expansion and compression of each cell in the plurality of cells without a corresponding stress being generated on any of the plurality of cells. In this regard, the battery module disclosed herein, and associated expansion protection systems and methods, can result in significantly lighter battery modules that can produce a similar amount of energy' relative to a typical battery module, in accordance with various embodiments. Alternatively, the battery module disclosed herein, and associated expansion protection systems and methods, can result in a greater energy output for a similar weight relative to a typical battery module, in accordance with various embodiments.

[0007] The expansion protection system allows a length of an array of pouch cells to increase from a first length to a second length in response to charging the array of pouch cells. In this regard, the array of pouch cells are given freedom in a longitudinal direction to expand, and the expansion protection system can comprise a biasing mechanism to return the array of pouch cells to a default position after charging, in accordance with various embodiments.

[0008] The battery module and expansions protection systems disclosed herein can facilitate use of alternative battery chemistries compared to typical battery chemistries that have otherwise been avoided due to effects of their expansion during charging, in accordance with various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A more complete understanding of the present disclosure may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar elements throughout the Figures, and where:

[0010] Figure 1A illustrates a perspective view of a battery module, in accordance with various embodiments;

[0011] Figure IB illustrates a schematic view of a battery module, in accordance with various embodiments;

[0012] Figure 2 illustrates a perspective view of a battery module during charging, in accordance with various embodiments;

[0013] Figure 3 illustrates a detail view of a set of pouch cells in a battery module, in accordance with various embodiments;

[0014] Figure 4A illustrates a top view of a battery module in a charged state, in accordance with various embodiments; and

[0015] Figure 4B illustrates a top view of a battery module during a fully discharged state, in accordance with various embodiments; and

[0016] Figure 4C illustrates a top view of a battery module in a discharged state after vanous cycles of use, in accordance with various embodiments.

DETAILED DESCRIPTION

[0017] The following description is of various example embodiments only, and is not intended to limit the scope, applicability or configuration of the present disclosure in any way. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments including the best mode. As will become apparent, various changes may be made in the function and arrangement of the elements described in these embodiments, without departing from the scope of the appended claims. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Moreover, many of the manufacturing functions or steps may be outsourced to or performed by one or more third parties. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. As used herein, the tenns “coupled,” “coupling,” or any other variation thereof, are intended to cover a physical connection, an electrical connection, a magnetic connection, an optical connection, a communicative connection, a functional connection, and/or any other connection.

[0018] For the sake of brevity, conventional techniques for mechanical system construction, management, operation, measurement, optimization, and/or control, as well as conventional techniques for mechanical power transfer, modulation, control, and/or use, may not be described in detail herein. Furthermore, the connecting lines shown in various figures contained herein are intended to represent example functional relationships and/or physical couplings between various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a modular structure.

[0019] Energy cells have been developed for a wide range of applications using a variety of different technologies, resulting in a wide range of available performance characteristics. The nominal voltage of a galvanic cell is fixed by the electrochemical characteristics of the active chemicals used in the cell, the so called cell chemistry. The actual voltage appearing at the terminals at any particular time, as with any cell, depends on the load cunent and the internal impedance of the cell and this varies with, temperature, the state of charge and with the age of the cell.

[0020] There are various characteristics used to define a battery cell’s performance capabilities. For example, performance characteristics for a given battery cell can include discharge curves, discharge rates, duty cycle, cycle life, etc. Performance characteristics can change based on various cell or operating parameters. For example, performance characteristics can further depend on cell chemistry, operating conditions (e.g., operating temperature, discharge rate, etc.), or the like. Of growing importance, as battery cells are being utilized in aeronautical applications to a significantly larger degree is energy density for a battery cell (or a battery module as a whole). “Energy density” as referred to herein defines battery capacity in weight (Wh/kg). Stated another way, energy density for a battery cell (or a battery module) defines a discharge cunent the battery cell (or battery module) can deliver over time per unit of weight. As weight is a significant factor in aeronautical applications, energy density for battery modules is becoming increasingly important. [0021] Currently, lithium-ion batteries are the most common energy sources for cells that form battery modules and are known for having relatively high energy density. Alternative battery chemistries, such as lithium-silicon cells, have even greater energy density relative to lithium-ion cells; however, due to certain drawbacks, applications of these alternative battery chemistries have not been readily explored. In particular, lithium-silicon cells are prone to significant physical expansion of the material during charging of the cell. For example, during charging of a lithium-silicon cell, a volume of the cell may increase by approximately 320% its original volume. This expansion, and then contraction in discharge, can cause stress cracks to form in the material, increasing impedance and reducing capacity. For example, typical lithium-silicon based battery modules lose most of their capacity in as few as 10 charge-discharge cycles. Although described herein with respect to lithium-silicon based cells, the present disclosure is not limited in this regard, and any cell chemistry that results in expansion during charging is within the scope of this disclosure. For example, lithiumaluminum cells, lithium-tin cells, metallic lithium cells, or any other cell chemistry known for expansion during charging is within the scope of this disclosure.

[0022] Disclosed herein is a battery module having an expansion protection system. The battery module includes a plurality of cells electrically coupled together (e g., in series and/or in parallel). The battery module is configured to facilitate expansion and compression of each cell in the plurality of cells. In this regard, the battery module disclosed herein, and associated expansion protection systems and methods, can result in significantly lighter battery modules that can produce a similar amount of energy' relative to a typical battery module, in accordance with various embodiments. Alternatively, the battery module disclosed herein, and associated expansion protection systems and methods, can result in a greater energy output for a similar weight relative to a ty pical battery module, in accordance with various embodiments.

[0023] Referring now to FIGs. 1A and IB, a perspective view (FIG. 1A) and a schematic top view (FIG. IB) of a battery module 100 is illustrated, in accordance with various embodiments. The battery module 100 includes an expansion protection system 101. In various embodiments, the expansion protection system 101 is a passive system. For example, the expansion protection system 101 can passively facilitate expansion and contraction of an array of cells during charging (or operation) of the battery module, in accordance with various embodiments. Although described herein as including a passive expansion protection system 101, the present disclosure is not limited in this regard. For example, an active expansion protection system 101 where a pressure being applied to the battery module 100 is continuously monitored and/or adjusted is within the scope of this disclosure. In various embodiments, by having a passive system for the expansion protection system 101, a weight and part count of the battery module 100 can be greatly reduced relative to an active system, which provides additional benefits for aeronautical type applications.

[0024] In various embodiments, the battery module 100 comprises a plurality of pouch cells 110 including a first array of pouch cells 112 and a second array of pouch cells 114. Although illustrated as including two arrays of pouch cells (e.g., arrays of pouch cells 112, 114), the present disclosure is not limited in this regard. For example, any number of arrays of pouch cells is within the scope of this disclosure, such as a single array of pouch cells (e.g., the first array of pouch cells 112 only) to greater than 10 arrays of pouch cells (i.e., spaced apart laterally in the X-direction), in accordance with various embodiments.

[0025] In various embodiments, the first array of pouch cells 112 are disposed longitudinally (e g., in the Z-direction) between a first end plate 122 and a first pressure plate 124. Similarly, the second array of pouch cells 114 are disposed longitudinally (e.g., in the Z-direction) between a second end plate 132 and a second pressure plate 134. Although the end plates 122, 132 are illustrated as separate, distinct components, the present disclosure is not limited in this regard. For example, a single end plate can extend laterally (e.g., in the X-direction) across multiple arrays of pouch cells (e.g., from the first array of pouch cells 112 to the second array of pouch cells 114) and still be within the scope of this disclosure. Similarly, although the pressure plates 124, 134 are illustrated as separate, distinct components, the present disclosure is not limited in this regard. For example, a single pressure plate can extend laterally (e.g., in the X-direction) across multiple arrays of pouch cells (e.g., from the first array of pouch cells 112 to the second array of pouch cells 114) and still be within the scope of this disclosure.

[0026] In various embodiments, adjacent pouch cells in an array of pouch cells

112, 114 can abut (i.e., be in contact with) each other or be spaced apart from each other, or the like. The present disclosure is not limited in this regard. As described further herein, during charging of the battery module 100, the pouch cells in the array of pouch cells 112, 114 expand, which results in adjacent pouch cells in the array of pouch cells 112, 114 applying pressure to each other and causing the array of pouch cells 112, 114 to grow in total length.

[0027] In various embodiments, each array of pouch cells (e.g., the first array of pouch cells 112 and the second array of pouch cells 114) can comprise spacing plates, or separators (e.g., spacing plates 128, 138) spaced apart in the longitudinal direction (i.e., the Z-direction) of the battery module 100. In various embodiments, the spacing plates 128, 138 are conductive. In this regard, a tab of one pouch cell on a first side of the spacing plate 128, 138 and a tab of one pouch cell on a second side of the spacing plate 128, 138 can each be coupled to the spacing plate 128, 138 to continue an electrical path. However, the present disclosure is not limited in this regard. For example, the spacing plates 128, 138 can include an aperture for a bus bar, or the like to extend through connecting one tab on one side of the spacing plate 128 to another tab on a second side of the spacing plate 128, 138. In various embodiments, the spacing plates 128, 138 can provide additional rigidity to the expansion protection system 101. In various embodiments, the spacing plates 128, 138 can separate the array of pouch cells 112, 114 into smaller packs of cells (e.g., sets of pouch cells). In this regard, an array of 50 pouch cells can be separated into 5 sets of 10 pouch cells with a spacing plate 128, 138 separating each set of pouch cells, in accordance with various embodiments. In various embodiments, any suitable number of pouch cells and sets of pouch cells may be used. Thus, the expansion and compression of the expansion protection system 101 can be robustly controlled and more uniform relative to a system without the spacing plates 128, 138. In various embodiments, the spacing plates 128, 138 act as a way to separate sets of pouch cells in an array of pouch cells 112, 114 and/or to allow a flat surface for electrical connections made when the set of pouch cells in the array of pouch cells 112, 114 are pressed together during expansion, as described further herein. Although illustrated as including spacing plates 128, 138, the present disclosure is not limited in this regard, and one skilled in the art may recognize various configurations without the use of spacing plates 128 and still be within the scope of this disclosure.

[0028] In various embodiments, a first biasing mechanism 126 is operably coupled to the first pressure plate 124 and a second biasing mechanism 136 is operably coupled to the second pressure plate 134. Although illustrated as having a biasing mechanism 126, 136 for each array of pouch cells 112, 114, the present disclosure is not limited in this regard. For example, a single biasing mechanism for multiple arrays of pouch cells is within the scope of this disclosure. In another example, multiple biasing mechanisms could be used for each pressure plate 124, 134.

[0029] In various embodiments, by having separate and distinct end plates 122,

132, pressure plates 124, 134, biasing mechanisms 126, 136, and spacing plates 128, 138 for each array of pouch cells 112, 114, greater control over expansion and contraction for each individual array of pouch cells can be provided. In this regard, if the first array of pouch cells 112 is expanding more than the second array of pouch cells 114 at a given point in time, the first biasing mechanism 126 can supply a different pressure to the pressure plate 124 relative to a pressure supplied to the second pressure plate 134 by the second biasing mechanism 136.

[0030] In various embodiments, the biasing mechanisms 126, 136 are gas springs, mechanical springs, coil and leaf springs, combinations of springs and cables, or the like. In various embodiments, the biasing mechanism 126, 136 are gas springs. In this regard, gas springs are compact, have a long life span, and are completely self-contained as to not need anything else to work, in accordance with various embodiments. Additionally, in accordance with various embodiments, gas springs can be a lighter option relative to other biasing mechanism. Gas springs are light weight very' reliable and can have a longer working life than coil and leaf springs, in accordance with various embodiments.

[0031] In various embodiments, the biasing mechanisms 126, 136 each comprise a cylinder 141 and a piston 142. The piston 142 is coupled to a pressure plate (e.g., pressure plate 124 for biasing mechanism 126 and pressure plate 134 for biasing mechanism 136) at a first end of the piston 142. The piston 142 extends longitudinally (i.e., in the Z-direction) from the first end into the cylinder 141 to a second end of the piston 142. Disposed within the cylinder 141 on a side opposite the piston head of the piston 142, is a compressed gas (e.g., nitrogen), configured to provide a consistent pressure on the piston 142, which in turn provides a consistent pressure to the pressure plate (e.g., pressure plate 124 or pressure plate 134). In another example embodiment, the cylinder 141 is in contact with the pressure plate 124/134, and the piston 142 is in contact with a support structure 191.

[0032] In various embodiments, the cylinder 141 of the biasing mechanisms 126,

136 are each fixedly coupled to a support structure 191. Similarly, the end plates 122, 132 of the array of pouch cells 112, 114 are each fixedly coupled to a support structure 192. In various embodiments, the support structure 191 is fixed relative to the support structure 192. In various embodiments, the support structure 191, 192 can form a monolithic component. In this regard, a distance in the longitudinal direction (i.e., the Z-direction) between the support structure 191 and the support structure 192 remains constant (i.e., excluding minor variations due to vibrations or the like) during operation. The support structure 191, 192 can be an airframe, a housing specific to the battery module 100, or the like. The present disclosure is not limited in this regard. Thus, the end plates 122, 132 and the cylinder 141 of the biasing mechanisms 126, 136 are all fixed in six degrees of freedom, and the biasing mechanisms 126, 136 facilitate movement/expansion of the array of pouch cells 112, 114 in the longitudinal direction (i.e., the Z-direction defined by a thickness direction of the pouch cells 110).

[0033] In various embodiments, the battery module 100 comprises a positive terminal 152 and a negative terminal 154. In various embodiments, the positive terminal 152 and the negative terminal 154 of the battery module 100 can be on the same longitudinal side of the battery module 100 (i.e., opposite the biasing mechanisms 126, 136). In this regard, the positive terminal 152 and the negative terminal 154 can be disposed in a location with little to no displacement to facilitate electrical coupling to a respective electrical load. In various embodiments, the support structure 192 includes ports configured to receive the positive terminal 152 and the negative terminal 154. In various embodiments, the support structure 192 can transport the power generated from the battery module 100 to an external load or the support structure 192 can be a part of an electrical component powered by the battery module 100. The present disclosure is not limited in this regard.

[0034] In various embodiments, each cell in the array of pouch cells 112, 114 are electrically coupled together in series between the positive terminal 152 and the negative terminal 154 of the battery module. In this regard, an electrical path of the battery module 100 can define an accordion shape from a first longitudinal end of the array of pouch cells 112, 114 to a second longitudinal end of the array of pouch cells 112, 114. In various embodiments, the first array of pouch cells 112 is electrically coupled to the second array of pouch cells 114 at the longitudinal end proximal the biasing mechanisms 126, 136. In this regard, a conductive element 162 extends laterally (i. e. , in the X-direction) from a tab 161 at a longitudinal end of the first array of pouch cells 112 to a tab 163 at a longitudinal end of the second array of pouch cells 114. In various embodiments, the tabs 161, 163 can be a part of a last pouch cell in the array of pouch cells 112, 114, a tab extending from a spacing plate 128, 138, or a tab extending from a pressure plate 124, 134. The present disclosure is not limited in this regard.

[0035] Referring now to FIG. 2, a perspective view of the battery module 100 in a charging state is illustrated, in accordance with various embodiments. A “charging state” as referred to herein, is a state where energy is being stored in the battery module 100 by running electrical current through the plurality of pouch cells 1 10. In various embodiments, for certain pouch cell chemistries, such as lithium silicon pouch cells, while the battery module 100 is in a charging state, each pouch cell in the plurality of pouch cells 110 expands in a thickness direction (i.e., the Z- direction) to a significantly greater degree relative to most commercially available pouch cells, such as lithium-ion pouch cells. In this regard, in response to each pouch cell in the plurality of pouch cells 110 expanding during charging of the battery module 100, a biasing force on the pressure plates 124, 134 is exceeded by a pressure due to expansion of each pouch cell in the plurality of pouch cells 110 in the longitudinal direction (i.e., the Z-direction). In response to the biasing force from the biasing mechanisms 126, 136 being exceeded, the piston 142 of each biasing mechanism 126, 136 travels longitudinally into the cylinder 141 until an equilibrium is met, or until the pressure plate 124, 134 contacts the cylinder 141. In various embodiments, the biasing mechanism is configured to reach an equilibrium force during charging. In this regard, an array of pouch cells 112, 114 can have a consistent pressure supplied in the longitudinal direction (i.e., the Z- direction) during charging and during operation (i.e. discharging) regardless of a thickness of each pouch cell in the plurality of pouch cells 110.

[0036] In various embodiments, the electrical coupling between adjacent pouch cells in the plurality of pouch cells 110 can further facilitate the expansion and compression of the array of pouch cells 112, 114 For example, with reference to FIG. 3, a perspective detail view of a set of pouch cells 300 in an array of pouch cells (e.g. the first array of pouch cells 112 or the second array of pouch cells 114 from FIGs. 1A, IB, and 2) is illustrated, in accordance with various embodiments. Typical battery modules including pouch cells include rigid bus bars between tabs that are electrically coupled together, or a common bus bar extending along a row of tabs.

[0037] In contrast, the set of pouch cells 300 have adjacent tabs coupled together to increase flexibility of the set of pouch cells 300 in the longitudinal direction (i.e., the Z-direction) as described previously herein. The set of pouch cells 300 includes pouch cells 310, 320, 330. The pouch cell 320 is disposed between (i.e., in the Z-direction) a pouch cell 310 and a pouch cell 330. A tab 312 of the pouch cell 310 is coupled to a first tab 322 of the pouch cell 320 on a first lateral side of the pouch cells 310, 320, 330. Similarly, a second tab 324 of the pouch cell 320 is coupled to a tab 334 of the pouch cell 330 on a second lateral side of the pouch cells 310, 320, 330. In this regard, the electrical connections of an array of pouch cells 112, 114 with the set of pouch cells 300 defines an accordion like shape, in accordance with various embodiments. Thus, expansion and contraction of the set of pouch cells 300 is further facilitated by the configuration of electrical couplings between pouch cells in each set of pouch cells 300 of an array of pouch cells 112, 114 from FIGs. 1A, IB, and 2.

[0038] Although illustrated as having the set of pouch cells 300 coupled together in series, the present disclosure is not limited in this regard. For example, the set of pouch cells 300 could be connected in parallel by aligning the positive tabs of each cell along a longitudinal axis (e.g., the Z-direction), and extending a flexible bus bar along a length of the tabs. In various embodiments, the flexible bus bar could comprise various bends to facilitate expansion and compression of the bus bar during expansion and compression of the battery module 100 as described previously herein.

[0039] In various embodiments, the series configuration, as shown in FIG. 3, provides a simpler manufacturing process and maintains the flexibility of the expansion protection system 101 via the accordion shape, in accordance with various embodiments. Moreover, in another example embodiment, a group (e.g. two) of adjacent pouch cells could be configured in parallel by connecting positive tabs on a first lateral side and negative tabs on a second lateral side, and these parallel connected pouch cells could then be connected in series using the same accordion arrangement described above in connection with FIG. 3.

[0040] Referring now to FIGs. 4A, 4B, and 4C, a top view of the battery module

100 in a charging (or charged) configuration 401 (FIG. 4A) and a fully discharged (or default) configuration 402 (FIG. 4B), and a discharging (or discharged) configuration 403 (FIG. 4C) after various cycles of use are illustrated, in accordance with various embodiments. In the charged configuration 401, an array of pouch cells (e.g., first array of pouch cells 112 and/or second array of pouch cells 114) comprise a longitudinal length LI (i.e., in the Z-direction) measured from the end plate (e.g., end plate 122 or end plate 132) to the pressure plate (e.g., pressure plate 124 or pressure plate 134). Similarly, in the fully discharged (or default) configuration 402, the array of pouch cells (e g., first array of pouch cells 112 and/or second array of pouch cells 114) comprise a second length L2 that is less than the first length LI. In this regard, in response to the pouch cells in the array of pouch cells 112, 114 expanding during charging, a length of the array of pouch cells increases from the longitudinal length L2 in the fully discharged (or default) configuration 402 to the longitudinal length LI in the charged configuration 401. Moreover, in various embodiments, the array of pouch cells 112, 114 may expand during charging from a longitudinal length L2 to a longitudinal length LI and then return from the longitudinal length LI to the longitudinal length L2 in response to discharging (or to another length L3 in response to discharging). It should be understood that the cells may not return back to their original size and therefore the array length after discharging may become longer over time (i.e., the longitudinal length L3 is greater than the longitudinal length L2).

[0041] In various embodiments, the longitudinal length LI can be between 5% and 35% greater than the longitudinal length L2, or between 10% and 35% greater than longitudinal length L2, or approximately 25% greater than the longitudinal length L2. In this regard, the expansion protection system 101 can facilitate the use of pouch cell chemistries, such as lithium-silicon pouch cells or the like, that are prone to swelling, or significant volume expansion, during charging without resultant fracturing or crumbling of materials within the pouch cells due to increases stresses. Thus, the expansion protection system 101 can facilitate the use of alternative battery cell chemistries with greater specific capacity compared to typical battery cell chemistries, in accordance with various embodiments.

[0042] While the principles of this disclosure have been shown in various embodiments, many modifications of structure, arrangements, proportions, elements, materials and components (which are particularly adapted for a specific environment and operating requirements) may be used without departing from the principles and scope of this disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure and may be expressed in the following claims.

[0043] The present disclosure has been described with reference to various embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure. Likewise, benefits, other advantages, and solutions to problems have been described above with regard to various embodiments.

[0044] However, benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0045] When language similar to “at least one of A, B, or C” or “at least one of A,

B, and C” is used in the claims or specification, the phrase is intended to mean any of the following: (1) at least one of A; (2) at least one of B; (3) at least one of C;

(4) at least one of A and at least one of B; (5) at least one of B and at least one of C; (6) at least one of A and at least one of C; or (7) at least one of A, at least one of B, and at least one of C

Claims

CLAIMS We claim:

1. A battery module, comprising: an end plate; a pressure plate spaced apart from the end plate by a distance; an array of pouch cells disposed between the end plate and the pressure plate; and an expansion protection system configured to allow the distance to increase from a first length to a second length in response to charging the array of pouch cells.

2. The battery module of claim 1, wherein the second length is between 10% and 35% greater than the first length.

3. The battery module of claim 1, wherein the expansion protection system comprises a biasing mechanism coupled to the pressure plate.

4. The battery module of claim 3, wherein the biasing mechanism comprises a spring.

5. The battery module of claim 4, wherein the spring comprises a gas spring.

6. An expansion protection system, comprising: a first end plate; a first pressure plate configured to be spaced apart from the first end plate by a first distance, the first pressure plate and the first end plate configured to receive a first array of pouch cells therebetween; and a first biasing mechanism coupled to the first pressure plate, the first biasing mechanism configured to supply passive pressure to the first pressure plate during operation, the expansion protection system configured to allow the first distance to increase from a first length to a second length in response to charging the first array of pouch cells.

7 The expansion protection system of claim 6, wherein the second length is between 10% and 35% greater than the first length.

8. The expansion protection system of claim 6, further comprising: a second end plate; a second pressure plate configured to be spaced apart from the second end plate by a second distance, the second pressure plate and the second end plate configured to receive a second array of pouch cells therebetween; and a second biasing mechanism coupled to the second pressure plate, the first biasing mechanism configured to supply passive pressure to the second pressure plate during operation, the expansion protection system configured to allow the second distance to increase from the first length to the second length in response to charging the second array of pouch cells.

9. The expansion protection system of claim 8, wherein the first biasing mechanism and the second biasing mechanism each comprise a spring.

10. The expansion protection system of claim 9, wherein the spring comprises a cylinder and a piston.

11. The expansion protection system of claim 10, wherein the cylinder of the first biasing mechanism is operably coupled to the first pressure plate, and wherein the cylinder of the second biasing mechanism is coupled to the second pressure plate.

12. The expansion protection system of claim 11, further comprising a first support structure coupled to the cylinder of the first biasing mechanism and the second biasing mechanism.

13. The expansion protection system of claim 12, further comprising a second support structure coupled to the first end plate and the second end plate.

14. The expansion protection system of claim 10, wherein: a pouch cell of the plurality of pouch cells of the first array of pouch cells experiences a first stress in response to charging the plurality of cells; and the first stress is less than a second stress the pouch cell would experience if the pouch cell was fixed relative to the first end plate.