EXPANSION SYSTEMS AND METHODS FOR BATTERY PACK

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.

FIELD OF INVENTION

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

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.

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

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.

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.

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

DETAILED DESCRIPTION

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 terms “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.

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.

As referred to herein, “abuts” means in contact with. Abuts can mean in loose contact with, coupled to (e.g., fixedly or moveably coupled to), or the like. The present disclosure is not limited in this regard.

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 current and the internal impedance of the cell and this varies with, temperature, the state of charge and with the age of the cell.

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 current 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.

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, lithium-aluminum cells, lithium-tin cells, metallic lithium cells, or any other cell chemistry known for expansion during charging is within the scope of this disclosure.

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 typical battery module, in accordance with various embodiments.

Referring now toFIG.1a schematic top view of a battery module100is illustrated, in accordance with various embodiments. The battery module100includes an expansion protection system101and an array of pouch cells110. In various embodiments, the expansion protection system101is configured to maintain a pressure supplied to the array of pouch cells110as each pouch cell in the array of pouch cells110expand and contract as described further herein. In various embodiments, each pouch cell in the array of pouch cells110is a lithium-silicon based cell. Although described herein as lithium-silicon based cells, the present disclosure is not limited in this regard. For example, other cell chemistries, that swell, such as lithium-aluminum based cells are within the scope of this disclosure.

In various embodiments, each pouch cell in the array of pouch cells110is one of a lithium-silicon based cell or a lithium-metal based cell. In this regard, each pouch cell in the array of pouch cells110can include a higher energy density relative to typical cells and be configured to expand significantly more during charging relative to typical cells, in accordance with various embodiments.

In various embodiments, the expansion protection system101is a passive system. For example, the expansion protection system101can passively facilitate expansion and contraction of an array of cells during charging (or operation) of the battery module100, in accordance with various embodiments. Although described herein as including an expansion protection system101that is passive, the present disclosure is not limited in this regard. For example, an expansion protection system101can be an active expansion protection system (i.e., where a pressure being applied to the battery module100is continuously monitored and/or adjusted) and is still within the scope of this disclosure. In various embodiments, by having a passive system for the expansion protection system101, a weight and part count of the battery module100can be greatly reduced relative to an active system, which provides additional benefits for aeronautical type applications.

In various embodiments, the array of pouch cells110include a first row of pouch cells112and a second row of pouch cells114. Although illustrated as including two rows of pouch cells (e.g., rows of pouch cells112,114), the present disclosure is not limited in this regard. For example, any number of rows of pouch cells is within the scope of this disclosure, such as a single row of pouch cells (e.g., the first row of pouch cells112only) to greater than 10 rows of pouch cells (i.e., spaced apart laterally in the X-direction), in accordance with various embodiments. In various embodiments, by having an even number of rows of pouch cells, a positive terminal152and a negative terminal154for the array of pouch cells110can be disposed on the same side of the battery module (i.e., a fixed side). In this regard, a terminal of the array of pouch cells110will not have to be configured to translate during charging or discharging of the array of pouch cells110as described further herein.

In various embodiments, the battery module100further comprises a support structure191spaced apart longitudinally (i.e., in a Z-direction) from a support structure192. The array of pouch cells110are configured to be disposed between the support structures191,192. The expansion protection system101includes a biasing system130. The biasing system130is disposed between the support structure191and the array of pouch cells110. In various embodiments, the biasing system130is coupled to the support structure191. However, the present disclosure is not limited in this regard. For example, the biasing system130can be configured to abut the support structure191without a hard connection, as described further herein, and still be within the scope of this disclosure.

The biasing system130may be spaced apart from the support structure192by a distance D1. The expansion protection system101is configured to allow the distance D1to increase from a first length (e.g., length L2fromFIG.4B) to a second length (e.g., length L1fromFIG.4A) in response to transitioning the battery module100from a discharged state (FIG.4B) to a charged state (FIG.4A), as described further herein.

In various embodiments, each pouch cell in a row of pouch cells112,114abuts an adjacent pouch cell in the row of pouch cells112,114. In various embodiments, a majority of pouch cells in each row of pouch cells112,114abuts two adjacent pouch cells in the row of pouch cells112,114. For example, a first pouch cell171in the array of pouch cells110abuts a second pouch cell172on a first side (i.e., a first longitudinal side) and a third pouch cell173on a second side (i.e., a second longitudinal side). Each pouch cell in the array of pouch cells110comprises a positive tab spaced apart laterally (i.e., in an X-direction) from a negative tab. For example, the first pouch cell171comprises a positive tab181spaced apart laterally from a negative tab182. In various embodiments, the positive tab181of the first pouch cell171is physically and electrically coupled to the negative tab182of the second pouch cell172on a first lateral side of the first pouch cell171. Similarly, the negative tab182of the first pouch cell171is physically and electrically coupled to the positive tab of the third pouch cell on a second lateral side of the first pouch cell. In this regard, the row of pouch cells112,114can form an electrical path in series from pouch cell to pouch cell, in accordance with various embodiments. In various embodiments, by coupling the pouch cells in the array of pouch cells110as described herein, each row of pouch cells112,114can expand and contract in a similar manner to an accordion. Accordingly, a stress experienced by each pouch cell in the array of pouch cells110can be greatly reduced relative to a system with a current collector, or other typical bus bars, which fix the pouch cells relative to the bus bars, in accordance with various embodiments.

In various embodiments, as described further herein, the biasing system130comprises at least one biasing mechanism. In various embodiments, the biasing mechanism is configured to abut the support structure191and/or be coupled to the support structure191. The present disclosure is not limited in this regard. For example, the biasing system130can comprise a bladder (e.g., bladder502as shown inFIGS.5A,5B), a plurality of the bladder (e.g., the plurality of the bladder502as shown inFIGS.6A,6B), a spring (e.g., biasing mechanism126or136as shown inFIGS.2A,2B), or the like. In various embodiments, the biasing system130can include a combination of bladder(s) and/or springs. The present disclosure is not limited in this regard.

In various embodiments, the first row of pouch cells112are disposed longitudinally (i.e., in the Z-direction) between end plate122and a pressure plate124. Similarly, the second row of pouch cells114are disposed longitudinally (e.g., in the Z-direction) between end plate132and pressure plate134. Stated another way, the first row of pouch cells112are spaced apart laterally (i.e., in the X-direction) from the second row of pouch cells114. Although the end plates122,132are 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 row of pouch cells112to the second row of pouch cells114) and still be within the scope of this disclosure. In various embodiments, the end plates122,132, can be eliminated, and the array of pouch cells110can be coupled to the support structure192directly. The present disclosure is not limited in this regard.

Similarly, although the pressure plates124,134are 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 row of pouch cells112to the second row of pouch cells114) and still be within the scope of this disclosure. In various embodiments, by having separate pressure plates124,134, a difference in expansion between adjacent arrays can be controlled, resulting in reduced stresses compared to having a single pressure plate.

In various embodiments, adjacent pouch cells in a row of pouch cells112,114can 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 module100, the pouch cells in the row of pouch cells112,114expand, which results in adjacent pouch cells in the row of pouch cells112,114applying pressure to each other and causing the row of pouch cells112,114to grow in total length.

In various embodiments, a biasing system130is operably coupled to the pressure plate124and the pressure plate134. As described further herein, the biasing system130can comprise a single biasing mechanism between the pressure plates124,134and a support structure191, a first biasing mechanism coupled to the pressure plate124and a second biasing mechanism coupled to the pressure plate134, or a plurality of biasing mechanisms spaced apart longitudinally in the row of pouch cells112,114. The present disclosure is not limited in this regard, and as described further herein there can be various advantages to various configurations.

In various embodiments, the battery module100comprises a positive terminal152and a negative terminal154. In various embodiments, the positive terminal152and the negative terminal154of the battery module100can be on the same longitudinal side of the battery module100(i.e., opposite, or distal to, the support structure191and the biasing system130). In this regard, the positive terminal152and the negative terminal154can be disposed in a location with little to no displacement (e.g., a fixed location) to facilitate electrical coupling to a respective electrical load and/or to prevent damage to the electrical connection. In various embodiments, the array of pouch cells110define an electrical path from the positive terminal152to the negative terminal. In this regard, the electrical path can extend from the positive terminal152, then from pouch cell to pouch cell in the first row of pouch cells112from the first longitudinal end of the battery module100(i.e., proximal the support structure192) to the second longitudinal end of the battery module100, then from pouch cell to pouch cell in the second row of pouch cells114from the second longitudinal end of the battery module100to the first longitudinal end of the battery module100, then to the negative terminal154, in accordance with various embodiments.

In various embodiments, the end plate122can comprise a pouch cell in the row of pouch cells112that defines the positive terminal152. However, the present disclosure is not limited in this regard. For example, the end plate122can include a conductive element or the like electrically coupling a pouch cell in the row of pouch cells112to the positive terminal152, in accordance with various embodiments. Similarly, the end plate132can comprise a pouch cell in the row of pouch cells114that defines the negative terminal154. However, the present disclosure is not limited in this regard. For example, the end plate132can include a conductive element or the like electrically coupling a pouch cell in the row of pouch cells114to the negative terminal154, in accordance with various embodiments. In various embodiments, the end plate122is disposed laterally adjacent to the end plate132. “Laterally adjacent”, as referred to herein corresponds to being spaced apart in a lateral direction at a same longitudinal location of the battery module relative to the support structure192, in accordance with various embodiments.

In various embodiments, the support structure192includes ports configured to receive the positive terminal152and the negative terminal154. In various embodiments, the support structure192can transport the power generated from the battery module100to an external load or the support structure192can be a part of an electrical component powered by the battery module100. The present disclosure is not limited in this regard.

In various embodiments, each cell in the row of pouch cells112,114are electrically coupled together in series between the positive terminal152and the negative terminal154of the battery module. In this regard, an electrical path of the battery module100can define an accordion shape from a first longitudinal end of the row of pouch cells112,114to a second longitudinal end of the row of pouch cells112,114. In various embodiments, the first row of pouch cells112is electrically coupled to the second row of pouch cells114at the longitudinal end proximal the biasing mechanisms126,136. In this regard, a conductive element162extends laterally (i.e., in the X-direction) from a tab161at a longitudinal end of the first row of pouch cells112to a tab163at a longitudinal end of the second row of pouch cells114.

Referring now toFIGS.2A and2B, a perspective view of a battery module100with an expansion protection system101in fully discharged (or discharged) state201(FIG.2A) and a fully charged (or charged) state202(FIG.2B) are illustrated, with like numerals depicting like elements, in accordance with various embodiments. In various embodiments, a “discharged configuration” as referred to herein, is a newly manufactured state (i.e., a state where the battery module100has not undergone any charging or discharging cycles). In various embodiments, a “charged state” as referred to herein is a state of the battery module100after a charge. In various embodiments, after numerous charge and discharge cycles (i.e., various battery life cycles), a length of the row of pouch cells112,114in the charged state202can increase relative to an initial charge state (i.e., after the battery module100is manufactured). In this regard, after each battery life cycle, the pouch cells in the array of pouch cells110can expand further than a prior state. In response to the expansion, the biasing system130can maintain a consistent pressure on the array of pouch cells110as described further herein. Accordingly, the expansion protection system101can extend a life of the array of pouch cells110by preventing damage to cells in the array of pouch cells in response to the expansion of the pouch cells, in accordance with various embodiments.

With reference now toFIG.2A, in various embodiments, the battery module100can further comprise spacing plates, or separators (e.g., spacing plates128,138). For example, each array of pouch cells110(e.g., the first row of pouch cells112and the second row of pouch cells114) can comprise spacing plates128,138spaced apart in the longitudinal direction (i.e., the Z-direction) of the battery module100. In various embodiments, the spacing plates128,138are conductive. In this regard, a tab of one pouch cell on a first side of the spacing plate128,138and a tab of one pouch cell on a second side of the spacing plate128,138can each be coupled to the spacing plate128,138to continue an electrical path. However, the present disclosure is not limited in this regard. For example, the spacing plates128,138can include an aperture for a bus bar, or the like to extend through connecting one tab on one side of the spacing plate128to another tab on a second side of the spacing plate128,138.

In various embodiments, the spacing plates128,138can provide additional rigidity to the expansion protection system101. In various embodiments, the spacing plates128,138can separate the row of pouch cells112,114into 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 plate128,138separating 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 system101can be robustly controlled and more uniform relative to a system without the spacing plates128,138. In various embodiments, the spacing plates128,138act as a way to separate sets of pouch cells in a row of pouch cells112,114and/or to allow a flat surface for electrical connections made when the set of pouch cells in the row of pouch cells112,114are pressed together during expansion, as described further herein. Although illustrated as including spacing plates128,138, the present disclosure is not limited in this regard, and one skilled in the art may recognize various configurations without the use of spacing plates128and still be within the scope of this disclosure. For example, as described further herein, the spacing plates128can be replaced with biasing mechanisms of the biasing system130, in accordance with various embodiments, and as described further herein.

With continued reference toFIGS.2A and2B, in various embodiments, the biasing system130comprises biasing mechanism126and biasing mechanism136. For example, the pressure plate124can be spaced apart from the support structure191. Similarly, the pressure plate134can be spaced apart from the support structure191. The biasing mechanism126can be coupled to the pressure plate124, and the biasing mechanism136can be coupled to the pressure plate134. In this regard, the biasing mechanism126can be configured to supply a passive pressure to the pressure plate124independently of a passive pressure supplied by the biasing mechanism136to the pressure plate134.

In various embodiments, by having separate and distinct end plates122,132, pressure plates124,134, biasing mechanisms126,136, and spacing plates128,138for each row of pouch cells112,114, greater control over expansion and contraction for each individual row of pouch cells can be provided. In this regard, if the first row of pouch cells112expands more than the second row of pouch cells114at a given point in time, the biasing mechanism126can supply a different pressure to the pressure plate124relative to a pressure supplied to the pressure plate134by the biasing mechanism136.

In various embodiments, the biasing mechanisms126,136are gas springs, mechanical springs, coil and leaf springs, combinations of springs and cables, or the like. In various embodiments, the biasing mechanism126,136are 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 mechanisms. Gas springs are light weight very reliable and can have a longer working life relative to coil and leaf springs, in accordance with various embodiments.

In various embodiments, the biasing mechanisms126,136each comprise a cylinder141and a piston142. The piston142is coupled to a pressure plate (e.g., pressure plate124for biasing mechanism126and pressure plate134for biasing mechanism136) at a first end of the piston142. The piston142extends longitudinally (i.e., in the Z-direction) from the first end into the cylinder141to a second end of the piston142. Disposed within the cylinder141on a side opposite the piston head of the piston142, is a compressed gas (e.g., nitrogen), configured to provide a consistent pressure on the piston142, which in turn provides a consistent pressure to the pressure plate (e.g., pressure plate124or pressure plate134).

In various embodiments, the cylinder141of the biasing mechanisms126,136are each fixedly coupled to the support structure191. Similarly, the end plates122,132of the row of pouch cells112,114are each fixedly coupled to the support structure192. In various embodiments, the support structure191is fixed relative to the support structure192. In various embodiments, the support structure191,192can form a monolithic component. In this regard, a distance in the longitudinal direction (i.e., the Z-direction) between the support structure191and the support structure192remains constant (i.e., excluding minor variations due to vibrations or the like) during operation. The support structure191,192can be an airframe, a housing specific to the battery module100, or the like. The present disclosure is not limited in this regard. Thus, the end plates122,132and the cylinder141of the biasing mechanisms126,136are all fixed in six degrees of freedom, and the biasing mechanisms126,136facilitate movement of the row of pouch cells112,114in the longitudinal direction (i.e., the Z-direction defined by a thickness direction of the pouch cells110).

In various embodiments, the tabs161,163can be a part of a last pouch cell in the row of pouch cells112,114, a tab extending from a spacing plate128,138, or a tab extending from a pressure plate124,134. The present disclosure is not limited in this regard.

In various embodiments, the expanded state ofFIG.2Bcan also be called a charged state. A “charged state” as referred to herein, is a state where energy is stored in the battery module100(e.g., at or near a maximum capacity of the battery module100). In various embodiments, for certain pouch cell chemistries, such as lithium silicon pouch cells, while the battery module100is charging, each pouch cell in the array of pouch cells110expands 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 array of pouch cells110expanding during charging of the battery module100, a biasing force on the pressure plates124,134is exceeded by a pressure due to expansion of each pouch cell in the array of pouch cells110in the longitudinal direction (i.e., the Z-direction). In response to the biasing force from the biasing mechanisms126,136being exceeded, the piston142of each biasing mechanism126,136travels longitudinally into the cylinder141until an equilibrium is met, or until the pressure plate124,134contacts the cylinder141. In various embodiments, the biasing mechanism is configured to reach an equilibrium force after charging. In this regard, a row of pouch cells112,114can have a consistent pressure supplied in the longitudinal direction (i.e., the Z-direction) during charging, after charging, and during operation (i.e., discharging) regardless of a thickness of each pouch cell in the array of pouch cells110.

In various embodiments, the electrical coupling between adjacent pouch cells in the array of pouch cells110can further facilitate the expansion and compression of the row of pouch cells112,114. For example, with reference toFIG.3, a perspective detail view of a set of pouch cells300in an array of pouch cells (e.g., the first row of pouch cells112or the second row of pouch cells114fromFIGS.1A,1B, and2) 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.

In contrast, the set of pouch cells300have adjacent tabs coupled together to increase flexibility of the set of pouch cells300in the longitudinal direction (i.e., the Z-direction) as described previously herein. The set of pouch cells300includes pouch cells310,320,330. The pouch cell320is disposed between (i.e., in the Z-direction) a pouch cell310and a pouch cell330. A tab312of the pouch cell310is coupled to a first tab322of the pouch cell320on a first lateral side of the pouch cells310,320,330. Similarly, a second tab324of the pouch cell320is coupled to a tab334of the pouch cell330on a second lateral side of the pouch cells310,320,330. In various embodiments, each tab (e.g., first tab322, and second tab324) can comprise at least two bends. The two bends can facilitate flexibility for the electrical connection, in accordance with various embodiments. In this regard, the electrical connections of a row of pouch cells112,114with the set of pouch cells300defines an accordion like shape, in accordance with various embodiments. Thus, expansion and contraction of the set of pouch cells300is further facilitated by the configuration of electrical couplings between pouch cells in each set of pouch cells300of a row of pouch cells112,114fromFIGS.1A,1B, and2.

Although illustrated as having the set of pouch cells300coupled together in series, the present disclosure is not limited in this regard. For example, the set of pouch cells300could 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 module100as described previously herein.

In various embodiments, the series configuration, as shown inFIG.3, provides a simpler manufacturing process and maintains the flexibility of the expansion protection system101via 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 withFIG.3.

Referring now toFIGS.4A,4B, and4C, a top view of the battery module100in a charging (or charged) state401(FIG.4A) and a fully discharged (or discharged) state402(FIG.4B), and a discharging (or discharged) configuration403(FIG.4C) after various cycles of use are illustrated, in accordance with various embodiments. In the charged state401, an row of pouch cells (e.g., first row of pouch cells112and/or second row of pouch cells114) comprise a longitudinal length L1(i.e., in the Z-direction) measured from the end plate (e.g., end plate122or end plate132) to the pressure plate (e.g., pressure plate124or pressure plate134). Similarly, in the fully discharged (or default) state402, the row of pouch cells (e.g., first row of pouch cells112and/or second row of pouch cells114) comprise a second length L2that is less than the first length L1. In this regard, in response to the pouch cells in the row of pouch cells112,114expanding during charging, a length of the array of pouch cells increases from the longitudinal length L2in the fully discharged (or default) state402to the longitudinal length L1in the charged state401. Moreover, in various embodiments, the row of pouch cells112,114may expand during charging from a longitudinal length L2to a longitudinal length L1and then return from the longitudinal length L1to the longitudinal length L2in response to discharging (or to another length L3in 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 L3is greater than the longitudinal length L2).

In various embodiments, the longitudinal length L1can 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 system101can 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 increased stresses. Thus, the expansion protection system101can facilitate the use of alternative battery cell chemistries with greater specific capacity compared to typical battery cell chemistries, in accordance with various embodiments.

Referring now toFIGS.5A and5B, a perspective view of a battery module100with an expansion protection system101having a bladder502as a biasing mechanism503of the biasing system130in a fully discharged (or discharged) state501(FIG.5A) and a fully charged (or charged) state509(FIG.5B) are illustrated, with like numerals depicting like elements, in accordance with various embodiments.

Referring now toFIG.5A, a perspective view of a portion of a battery module100with an expansion protection system101is illustrated in accordance with various embodiments. In various embodiments, the biasing system130of the expansion protection system101comprises a bladder502in fluid communication with a compressed fluid source506(i.e., a pressure vessel) via a fluid conduit504. In various embodiments, the bladder502is passively pressurized by the compressed fluid source506. In this regard, the bladder502can be directly fluidly coupled to the bladder502at a pre-set pressure to provide a substantially constant pressure to the set of pouch cells300of the battery module100. “Substantially constant” as referred to herein includes +/−10% from a nominal pressure or +/−5% from a nominal pressure, in accordance with various embodiments.

Although described, as being passively pressurized by the compressed fluid source506, the present disclosure is not limited in this regard. For example, a valve508can be disposed fluidly between the bladder502and the compressed fluid source506. In this regard, the valve508can be actively managed to vary a pressure provided to the bladder502, in accordance with various embodiments.

In various embodiments, the compressed fluid source506is external to the battery module100. Stated another way, the battery module100can include a housing105that includes the set of pouch cells300and the bladder502disposed therein, and the compressed fluid source506can be disposed external to the housing105. In various embodiments, the valve508can be internal or external to the housing105. The present disclosure is not limited in this regard.

In various embodiments, the expansion protection system500can be utilized with smaller stacks of cells (e.g., between 5 and 15 cells), or approximately 10 cells per stack. In this regard, variations in expansion between stacks of cells (e.g., the set of pouch cells300) can be more efficiently managed.

Referring now toFIG.5B, in the fully charged (or charged) state509, expansion of each cell in the set of pouch cells300can compress the bladder502until an equilibrium is reached. In this regard, the bladder502allows expansion of the cells in the set of pouch cells300without damage to the cells and/or a supporting structure, in accordance with various embodiments. In various embodiments, after numerous charge and discharge cycles (i.e., various battery life cycles) of battery module100with an expansion protection system101having a bladder502as the biasing system130, a length of in the charged state (FIG.6B) can increase relative to an initial charge state (i.e., after the battery module100is manufactured) (e.g.,FIG.6A) for each array of pouch cells (e.g., array of pouch cells622,624,626,628) in the plurality of battery modules620. In this regard, after each battery life cycle, the pouch cells in the array of pouch cells110can expand further than a prior state. In response to the expansion, the biasing system130can maintain a consistent pressure on each array of pouch cells (e.g., array of pouch cells622,624,626,628) as described previously herein. Accordingly, the expansion protection system601of the battery system605can extend a life of the array of the cells in the battery system600, by preventing damage to cells in the array of pouch cells in response to the expansion of the pouch cells, in accordance with various embodiments.

Referring now toFIGS.6A and6B, a top-down cross-sectional view of a battery system600with the expansion protection system101having a plurality of the biasing system130is illustrated in accordance with various embodiments. Although illustrated as including a plurality of the bladder502as the biasing system130, the present disclosure is not limited in this regard. For example, the battery system600can include a plurality of the springs as the biasing system130, in accordance with various embodiments, and as described previously herein.

In various embodiments, the battery system600comprises a housing610and a plurality of battery modules620(e.g., a plurality of sets of pouch cells300, also referred to herein as array of pouch cells622,624,626,628). The housing610defines a plurality of cavities (e.g., first cavity611, second cavity612, third cavity613, fourth cavity614, etc.). Although illustrated with four cavities in the plurality of cavities, the housing610is not limited in this regard. For example, any number of cavities of two or more for the battery system600is within the scope of this disclosure.

In various embodiments, each cavity is defined laterally between a first sidewall691and a second sidewall692. The first sidewall691and the second sidewall692each extend longitudinally (i.e., in a Z-direction) from a first longitudinal end of the housing610to a second longitudinal end of the housing610. Similarly, each cavity is defined longitudinally between a first support structure and a second support structure (e.g., between support structures615,616for the first cavity611, between support structures616,617for the second cavity612, between support structures617,618for the third cavity613, and between support structures618,619for the fourth cavity614). Accordingly, the support structures615,616,617,618,619each extend laterally from the first sidewall691to the second sidewall692. In various embodiments, the housing610includes an outer perimeter defined by the sidewalls691,692, and support structure615disposed at a first longitudinal end of the housing610and support structure619disposed at a second longitudinal end opposite from the first longitudinal end.

In various embodiments, each battery module in the plurality of battery modules620comprises a biasing system as described previously herein. For example, a first biasing system632can be disposed in the first cavity611, a second biasing system634can be disposed in the second cavity612, and so on. In this regard, each biasing system130has a corresponding cavity in the plurality of cavities. Accordingly, each array of pouch cells can have a biasing system adaptable to the respective array of pouch cells. In various embodiments, by separating a battery system600into various battery modules620(e.g., array of pouch cells622,624,626,628) with independent biasing systems (e.g., biasing systems632,634,636,638), a life of the battery system600can be improved relative to a battery system without the biasing systems, or a battery system with a single biasing system and the same number of cells.

The biasing system130is configured to abut a respective support structure defined by the housing610(e.g., biasing system632abuts supports the structure615, biasing system634abuts the support structure616, biasing system636abuts the support structure617, biasing system638abuts the support structure618). For example, the first biasing system632is configured as an expansion protection sub-system for the array of pouch cells622, the second biasing system634is configured as an expansion protection sub-system for the array of pouch cells624, and so on. In this regard, the first biasing system632is disposed in the first cavity611and configured to abut a support structure615(e.g., a first support structure) and a first longitudinal end of the array of pouch cells622. Similarly, the second biasing system634is disposed in the second cavity612and configured to abut a support structure616(e.g., a second support structure) and a first longitudinal end of the array of pouch cells624. In various embodiments, the support structure616for the second biasing system634abuts a second longitudinal end (e.g., a fixed end) of the first array of pouch cells622. In this regard, the first array of pouch cells622are configured to expand and compress in a longitudinal direction towards and away from the support structure615. Similarly, the second array of pouch cells is disposed longitudinally between the second biasing system634and the support structure617. In this regard, the second array of pouch cells624includes a fixed longitudinal end at the support structure617and is configured to translate relative to the support structure616.

In various embodiments, each array of pouch cells (e.g., array of pouch cells622,624,626,628) can be electrically coupled together to form the battery system600. For example, the array of pouch cells can be electrically coupled through the housing610(i.e., to ensure that each array of pouch cells is electrically coupled at a respective fixed end).

In various embodiments, each biasing system (e.g., biasing system632,634,636,638) includes a bladder (e.g., bladders642,644,646,648). In various embodiments, each bladder (e.g., bladders642,644,646,648) is configured to be fluidly coupled to a compressed fluid source506. In various embodiments, a valve508can be disposed between the bladders642,644,646,648and the compressed fluid source506. However, the present disclosure is not limited in this regard. For example, the battery system600can be without the valve508and still be within this disclosure. In this regard, the battery system600could supply a constant pressure to the bladders642,644,646,648, in accordance with various embodiments. In various embodiments, the valve508can be controlled through a controller (e.g., a processor and a non-transitory memory, or the like). Accordingly, a pressure supplied to the bladders642,644,646,648can be varied and still be within the scope of this disclosure.

In various embodiments, the array of pouch cells622,624,626,628each include two rows of pouch cells. In this regard, a high side (e.g., a positive side) of each array of pouch cells can be on a fixed side (e.g., on support structure616side for array of pouch cells622, on support structure617side for array of pouch cells624, on support structure618side for array of pouch cells626, and on support structure619side for array of pouch cells628). Similarly, the low side of each array of pouch cells can be disposed on the fixed side laterally adjacent to the first high side. Accordingly, the array of pouch cells can be electrically coupled in series from the fixed side to the moveable side (e.g., adjacent to the biasing system130) and back to the fixed side as shown, in accordance with various embodiments.

In various embodiments, after numerous charge and discharge cycles (i.e., various battery life cycles) of the battery system600, a length in the charged state (FIG.6B) can increase relative to a length in an initial charge state (i.e., after the battery modules600are manufactured) (e.g.,FIG.6A) for each array of pouch cells (e.g., array of pouch cells622,624,626,628). In this regard, after each battery life cycle, the pouch cells in the array of pouch cells622,624,626,628can expand further than a prior state. In response to the expansion, the biasing system130for each array of pouch cells (e.g., array of pouch cells622,624,626,628) can maintain a substantially constant pressure on each array of pouch cells (e.g., array of pouch cells622,624,626,628) as described previously herein. Accordingly, the expansion protection system601of the battery system605can extend a life of the array of the cells in the battery system600, by preventing damage to cells in the array of pouch cells in response to the expansion of the pouch cells, in accordance with various embodiments.

Referring now toFIG.7, a method700of assembling a battery module with an expansion protection system is illustrated, in accordance with various embodiments. The method700comprises electrically coupling a plurality of pouch cells to form an array of pouch cells (step702). In various embodiments, the plurality of pouch cells are coupled together in accordance with the set of pouch cells300fromFIG.3. In this regard, the plurality of pouch cells can be disposed adjacent to at least one pouch cell and have at least one tab coupled to an adjacent tab of an adjacent pouch cell. In various embodiments, each tab can have at least two bends to provide flexibility to the electrical interface during expansion and compression. In various embodiments, the array of pouch cells includes a first row and a second row (e.g., as shown inFIGS.1,2A-B,5A-B, and6).

In various embodiments, the method700further comprises disposing a biasing mechanism (e.g., biasing mechanisms126,136biasing mechanism502, or the like) adjacent to the first support structure (step704). In various embodiments, the first support structure is spaced apart longitudinally from a second support structure (e.g., support structures615being spaced apart longitudinally from support structure616, support structure191being spaced apart from support structure192, or the like).

In various embodiments, the method700further comprises disposing the array of pouch cells within a cavity between the biasing mechanism and a second support structure (e.g., between biasing mechanism126and support structure192as shown inFIGS.2A,2B, between biasing mechanism503and bladder642and support structure616as shown inFIGS.6A,6B, or the like) (step706).

In various embodiments, the method700can further comprise disposing a second biasing mechanism adjacent to the first support structure (e.g., biasing mechanism136being disposed adjacent to support structure191inFIGS.2A,2B). In various embodiments, the biasing mechanism can be configured to abut a first pouch cell in the first row of pouch cells (e.g., row of pouch cells112fromFIG.2A,2B), and the second biasing mechanism is configured to abut a second pouch cell in the second row of pouch cells (e.g., row of pouch cells114fromFIGS.2A,2B). In this regard, the first biasing mechanism and the second biasing mechanism can be disposed laterally adjacent to each other on a first longitudinal end of the battery system as shown inFIGS.2A,2B.

In various embodiments, the biasing mechanism of method700can be a bladder (e.g., bladder502fromFIG.5, bladder642,644,646,648fromFIG.6A,6B, or the like). In various embodiments, the method700can further comprise fluidly coupling a compressed fluid source (e.g., compressed fluid source506fromFIGS.6A,6B) to the bladder. The bladder can then be configured to supply a substantially constant pressure to at least one of the first row of pouch cells and the second row of pouch cells.

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.

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.

Example 1: A battery system, comprising: a housing defining a first cavity and a second cavity; a first biasing system disposed in the first cavity and configured to abut a first support structure; a second biasing system disposed in the second cavity and configured to abut a second support structure; a first array of pouch cells disposed longitudinally between the first biasing system and the second support structure; and a second array of pouch cells disposed longitudinally between the second biasing system and a third support structure.

Example 2: The battery system of example 1, wherein the first biasing system and the second biasing system each comprise a bladder.

Example 3: The battery system of example 2, further comprising a compressed fluid source in fluid communication with the bladder of the first biasing system and the bladder of the second biasing system.

Example 4: The battery system of example 1, wherein the first array of pouch cells is electrically coupled to the second array of pouch cells.

Example 5: The battery system of example 1, wherein the first array of pouch cells and the second array of pouch cells each comprise a first row of pouch cells and a second row of pouch cells.