Battery with thermally conductive filler material with thermal runaway control

Abstract

A battery (10) comprising: a housing (16) having an inner surface (26) which at least partially defines an interior space (18) of the housing (16); a battery cell stack (20) arranged in the interior (18) of the housing (16) such that a gap (24) exists between the battery cell stack (20) and the inner surface (26) of the housing (16), wherein the battery cell stack (20) comprises: a first battery cell group with at least two adjacent battery cells (44); a second battery cell group with at least two adjacent battery cells (44); and a partition wall (46) physically separating the first battery cell group from the second battery cell group, wherein each of the battery cells (44) of the first battery cell group and the second battery cell group comprises an electrode assembly (48) sealed in a box (50) and a positive electrode tab and a negative electrode tab (60, 62) electrically coupled to the electrode assembly (48) and extending from the electrode assembly (48) outside the box (50), and wherein the positive electrode tabs and / or the negative electrode tabs (60, 62) of the battery cells (44) extend into the gap (24) between the battery cell stack (20) and the inner surface (26) of the housing (16); and a filler material (22) that fills the gap (24) and provides a heat-conducting path between the positive electrode tabs and / or the negative electrode tabs (60, 62) of the battery cells (44) and the inner surface (26) of the housing (16), wherein the filler material (22) is in direct physical contact with the positive electrode tabs and / or the negative electrode tabs (60, 62) of the battery cells (44) and with the inner surface (26) of the housing (16), wherein the filler material (22) fills a region of the interior space (18) of the housing (16) defined by a plenum (42) that extends between a top surface (28) of the housing (16) and an upper end (34) of the battery cell stack (20), above upper sides (56) of the battery cells (44) and above upper ends (72) of the partition walls (46), wherein the filler material (22) forms a heat-conducting path between adjacent battery cells (44) and the top surface (28) of the housing (16) during normal operation of the battery (10) to help reduce heat gradients between the battery cells (44) and to dissipate heat from the battery cells (44) via the top surface (28) of the housing (16), wherein the filler material (22) comprises a thermally conductive particulate component distributed in a polymeric matrix component, wherein the heat-conducting particulate component comprises particles of at least one of the substances selected from the group consisting of: aluminum oxide, silicon dioxide, titanium dioxide, zeolite, aluminum nitride, or silicon carbide, wherein the polymeric matrix component comprises an organic polymer and / or a polysiloxane, and wherein the polymeric matrix component is configured to thermally decompose at temperatures higher than an upper operating temperature of the battery cells (44) to form a thermal and physical barrier that prevents heat transfer between the first battery cell group and the second battery cell group across the gap (24).

Description

introduction

[0001] The present invention relates to thermal management of rechargeable batteries, and more particularly to rechargeable batteries containing thermally conductive fillers having a thermal runaway control function.

[0002] A battery is a device that converts chemical energy into electrical energy through electrochemical reduction-oxidation (redox) reactions. In secondary batteries or rechargeable batteries, these electrochemical reactions are reversible, allowing the batteries to undergo multiple charge and discharge cycles. Electric vehicles, including hybrid electric vehicles, are powered by electric motors or generators, which in turn are usually powered by onboard rechargeable batteries. Such batteries typically comprise several individual electrochemical cells (referred to herein as battery cells) arranged in series and / or parallel, positioned side by side to form battery modules and / or battery packs, which, when incorporated into an electric vehicle's battery system, supply the vehicle with a combination of high voltage and high capacity.

[0003] Rechargeable batteries used in electric vehicles generate heat internally during normal charging and discharging processes. To optimize the performance and service life of such batteries, it is advantageous to use cooling systems that can effectively remove heat from the battery cells during operation to maintain the battery cell temperature within a desired operating temperature range. If a battery cell is subjected to certain abusive operating or charging conditions, or if a battery cell is manufactured with certain defects, the battery cell may generate a greater amount of heat than can be effectively removed from the battery cell by the cooling system, which can cause the battery cell to enter a condition known as thermal runaway.During a thermal runaway, the heat generated by the battery cell can be unlimited and can, in turn, cause neighboring battery cells to enter thermal runaway, potentially triggering a cascade reaction that can spread throughout an entire battery system. Furthermore, battery cells experiencing thermal runaway can release hot exhaust gases, sometimes near other battery system components that can be adversely affected by the temperature and / or composition of the exhaust gases.

[0004] To prevent the spread of thermal runaway between adjacent battery cells, thermal barriers may be placed between groups of battery cells to confine the heat generated during a thermal runaway to a small group of battery cells. To prevent the accumulation of exhaust gases and protect battery system components from such gases, the battery enclosures may include a venting system configured to direct and control the flow of exhaust gases through and out of the battery system.

[0005] DE 10 2014 221 870 A1 describes a battery having a plurality of battery cells connected in series or in parallel, each having a cell casing and an anode region emerging from the cell casing and a cathode region emerging from the cell casing, wherein the anode regions emerging from the cell casing and the cathode regions emerging from the cell casing of the plurality of battery cells are at least partially embedded in a potting compound, wherein the potting compound can be temperature-controlled by a temperature-control element.

[0006] US 2020 / 0 152 932 A1 describes a battery module with battery cells, a module housing in which the battery cells are housed, and a gap-filling material introduced into the module housing. The battery cells have a flat shape and store the battery elements in a flexible film bag. The gap-filling material is an elastic silicone material containing a thermally conductive filler and having a hardness of 80 or more for E hardness or 60 or more for A hardness. The gap-filling material is introduced between the battery cells and between the battery cell and the module housing on one side in a direction that intersects a direction in which the battery cells are arranged side by side, with the flat surfaces of the battery cells facing each other.The gap-filling material adheres to the battery cells to maintain a space between the battery cells and to conduct the heat generated by the battery cells to the module housing.

[0007] DE 10 2021 120 781 A1 describes a battery module comprising at least one cell group and a heat dissipation element coupled to one side of the at least one cell group for dissipating heat generated in the at least one cell group to the outside, wherein the at least one cell group comprises at least one battery cell stack, a flame-retardant cover coupled to the battery cell stack to enclose both side surfaces and an upper portion of the battery cell stack, and a flame-retardant element arranged between an upper surface of the battery cell stack and the flame-retardant cover and formed from porous material. Brief description of the invention

[0008] According to the invention, a battery comprises a housing having an inner surface that at least partially defines an interior space of the housing, and a battery cell stack arranged in an interior space of the housing. The battery cell stack is arranged inside the housing such that a gap exists between the battery cell stack and an inner surface of the housing. The battery cell stack comprises a first battery cell group with at least two adjacent battery cells and a second battery cell group with at least two adjacent battery cells. A partition physically separates the first battery cell group from the second battery cell group.Each of the battery cells of the first battery cell group and the second battery cell group includes an electrode assembly sealed in a box, and a positive electrode tab and a negative electrode tab electrically coupled to the electrode assembly and extending from the electrode assembly outside the box. The positive electrode tabs and / or the negative electrode tabs of the battery cells extend into the gap between the battery cell stack and the inner surface of the housing. A filler material fills the gap and provides a thermally conductive path between the positive electrode tabs and / or the negative electrode tabs of the battery cells and the inner surface of the housing. The filler material is in direct physical contact with the positive electrode tabs and / or the negative electrode tabs of the battery cells and with the inner surface of the housing.The fill material fills a region of the interior of the housing defined by a plenum extending between a top of the housing and a top end of the battery cell stack, above top sides of the battery cells, and above top ends of the partition walls. The fill material forms a thermally conductive path between adjacent battery cells and the top of the housing during normal battery operation to help reduce thermal gradients between the battery cells and conduct heat away from the battery cells across the top of the housing. The fill material comprises a thermally conductive particulate component dispersed within a polymeric matrix component. The thermally conductive particulate component comprises particles of at least one of the group consisting of: alumina, silicon dioxide, titanium dioxide, zeolite, aluminum nitride, or silicon carbide.The polymeric matrix component comprises an organic polymer and / or a polysiloxane. The polymeric matrix component is configured to thermally decompose at temperatures higher than an upper operating temperature of the battery cells to form a thermal and physical barrier that prevents heat transfer between the first battery cell group and the second battery cell group across the gap.

[0009] According to one embodiment, the polymeric matrix component is configured to thermally decompose at temperatures greater than or equal to 200°C to form a thermal and physical barrier that prevents heat transfer between a plurality of battery cells of the battery cell stack.

[0010] According to one embodiment, the polymeric matrix component has a thermal conductivity of less than 1 W / m·K, the thermally conductive particulate component has a thermal conductivity of more than 50 W / m·K, and the filler material has a thermal conductivity in the range of 3 W / m·K to 10 W / m·K.

[0011] According to one embodiment, the housing is in thermal contact with a heat sink. The filler material provides a thermally conductive path between the positive electrode tabs and the negative electrode tabs of the plurality of battery cells and the heat sink.

[0012] According to one embodiment, the battery comprises a battery management system with at least one integrated circuit. The filler material is arranged between the battery management system and the positive electrode terminals and / or the negative electrode terminals of the plurality of battery cells, and the polymeric matrix component of the filler material is configured to thermally decompose at temperatures greater than or equal to 200°C to form a thermal and physical barrier that prevents exhaust gases released from the battery cells from coming into direct physical or thermal contact with the battery management system. The filler material is in direct physical contact with the battery management system and forms a thermally conductive path between the at least one integrated circuit of the battery management system and the heat sink.

[0013] According to one embodiment, the housing has a top, a bottom, and a sidewall extending between the top and bottom of the housing, and the top, bottom, and sidewall at least partially define the interior of the housing. The battery cell stack is arranged inside the housing such that the gap extends between the battery cell stack and the sidewall of the housing, and the positive electrode tabs and / or the negative electrode tabs of the plurality of battery cells extend into the gap and are enclosed by the filler material.

[0014] According to one embodiment, the positive electrode tabs of the plurality of battery cells are electrically connected to a first bus bar, and the negative electrode tabs of the plurality of battery cells are electrically connected to a second bus bar. In this case, the first bus bar and the second bus bar are in direct physical contact with the filler material, and the filler material forms a thermally conductive path between the first bus bar, the second bus bar, and the heat sink.

[0015] The battery described herein may be implemented in a vehicle.

[0016] According to one embodiment, the housing is in thermal contact with a heat sink. In this case, the thermally conductive path provided by the filler material between the positive electrode tabs and / or the negative electrode tabs of the battery cells and the inner surface of the housing promotes conductive heat transfer between the positive electrode tabs and / or the negative electrode tabs of the battery cells and the heat sink.

[0017] According to one embodiment, the housing comprises a top, a bottom, and a sidewall extending between the top and the bottom of the housing. The top, bottom, and sidewall at least partially define the interior of the housing. The battery cell stack is arranged inside the housing such that the gap extends between the battery cell stack and the sidewall of the housing. The positive electrode tabs and / or the negative electrode tabs of the battery cells extend into the gap between the battery cell stack and the sidewall of the housing. The polymeric matrix component is configured to thermally decompose at temperatures above an upper operating temperature of the battery cells to form a thermal and physical barrier that prevents heat transfer between the first battery cell group and the second battery cell group across the gap.

[0018] The above summary is not intended to describe every possible embodiment of the present description. Rather, the above summary is intended to illustrate some of the novel embodiments and features described herein. The above features and advantages, as well as other features and advantages of the present description, will be readily apparent from the following detailed description of representative embodiments and modes for carrying out the present description, taken in conjunction with the accompanying drawings and the appended claims. Short description of the drawings

[0019] Illustrative embodiments are described below in conjunction with the accompanying drawings, wherein like reference numerals designate like elements and wherein: Fig. 1 is a schematic perspective view of a battery having a battery cell stack arranged in a housing, the battery cell stack including a plurality of battery cells and two partition walls arranged between adjacent battery cells, dividing the battery cells of the battery cell stack into first, second and third groups of battery cells. Fig. 2 a schematic perspective view of an electric vehicle with the battery of Fig. 1 is. Fig. 3 a schematic partial sectional side view of the battery of Fig. 1 showing the battery cell stack disposed within the housing and a filler material filling a cavity defined between an upper end of the battery cell stack and a top surface of the housing. Fig. 4 a schematic plan view of the battery of Fig. 1, which shows the battery cell stack arranged in the housing and a filler material that fills a gap formed between the battery cells of the battery cell stack and a side wall of the housing. Detailed description

[0020] The filler material presented here is used in a battery case to fill gaps or cavities between a battery cell stack arranged within the case and an interior surface of the case itself. The filler material is thermally conductive and forms a thermally conductive path between the battery cells of the battery cell stack and a heat sink connected to the battery. In all embodiments, the filler material is formulated to thermally decompose when exposed to thermal runaway temperatures to form a thermal barrier that prevents the propagation of thermal runaway through the battery cells of the battery cell stack.

[0021] In the following text, the term "battery" refers to a device containing multiple interconnected electrochemical cells (battery cells) arranged in series and / or parallel, and may refer to battery cells grouped together in the form of battery modules and / or battery packs. The term "approximately" means "within acceptable manufacturing tolerances" or "within 0-5% of."

[0022] In Fig. 1, a battery 10 is shown that can be used in an electrical power supply 12 of a vehicle 14, e.g., an electric vehicle (EV) or a hybrid electric vehicle (HEV), as shown in Fig. 2. The battery 10 comprises a housing 16 that at least partially defines an interior space 18, a battery cell stack 20 disposed in the interior space 18 of the housing 16, and a filler material 22 ( Fig. 3 and Fig. 4) which fills a gap 24 between an inner surface 26 of the housing 16 and the battery cell stack 20.

[0023] The housing 16 is configured to support the battery cell stack 20 within the vehicle 14 and to protect the battery cell stack 20 from environmental influences. The housing 16 includes a top 28, a bottom 30, and at least one sidewall 32 extending between the top 28 and the bottom 30 of the housing 16. A vent 29 may be located in the top 28 of the housing 16 to facilitate the pressure-induced escape of gas from the interior 18 of the housing 16. The housing 16 may be made of a thermally conductive material to dissipate heat from the battery cell stack 20 during operation. The housing 16 may be made of a metal, a metal alloy, or a polymer material with high thermal conductivity. For example, the housing 16 may be made of aluminum (Al) and / or copper (Cu). The housing 16 may be made of multiple components or may be fabricated from a single piece.

[0024] The battery cell stack 20 includes an upper end 34 adjacent to the top 28 of the housing and a lower end 36 resting on and in thermal contact with the bottom 30 of the housing 16. The bottom 30 of the housing 16 may be in thermal contact with a heat sink 38 that transfers thermal energy (i.e., heat) from the battery cell stack 20 to a heat transfer fluid (e.g., air or a liquid coolant) during operation of the battery 10. The heat sink 38 may include one or more passageways 40 that allow continuous flow of the heat transfer fluid through the heat sink 38 during operation of the battery 10. In some cases, the heat sink 38 may be defined by the bottom 30 of the housing 16. The battery cell stack 20 is arranged in the interior 18 of the housing 16 such that the battery cell stack 20 is spaced from at least one of the top side 28 or the side wall 32 of the housing 16.As in . Fig. 4, the battery cell stack 20 is arranged, for example, in the interior space 18 of the housing 16 such that a gap 24 is defined between at least one side wall 32 of the housing 16 and the battery cell stack 20. As shown in Fig. 3, the battery cell stack 20 is arranged in the interior space 18 of the housing 16 such that a plenum 42 is formed between the top side 28 of the housing 16 and the upper end 34 of the battery cell stack 20.

[0025] In the Fig. 1 and Fig. 3, the heat sink 38 is arranged adjacent to and in thermal contact with the bottom 30 of the housing 16; however, other arrangements are also possible. For example, the heat sink 38 may be arranged adjacent to and in thermal contact with the top 28 and / or at least one side wall 32 of the housing 16.

[0026] The battery cell stack 20 comprises a plurality of battery cells 44 arranged side by side and optionally one or more partition walls 46 which divide the battery cells 44 of the battery cell stack 20 into several groups of battery cells 44. In the Fig. 1, Fig. 3 and Fig. 4, the partition walls 46 separate the battery cells 44 of the battery cell stack 20 into groups of three adjacent battery cells 44; however, the number of battery cells 44 in each group of battery cells 44 may be less than or greater than three. Each of the battery cells 44 in the battery cell stack 20 includes an electrode assembly 48 (including a separator disposed between a positive electrode and a negative electrode) infiltrated with an electrolyte (not shown) and sealed in a box 50 ( Fig. 3 and Fig. 4). The box 50 of each battery cell 44 defines opposite first and second ends 52, 54 ( Fig. 1) and opposite upper and lower sides 56, 58 of the battery cell 44. A pair of electrically conductive positive and negative electrode tabs 60, 62 are electrically connected to the electrode assembly 48 and extend from the electrode assembly 48 outside the box 50. In the Fig. 1, Fig. 3 and Fig. 4, the positive and negative electrode tabs 60, 62 extend from the opposite first and second ends 52, 54 of the battery cells 44, respectively, into the gap 24 between the sidewall 32 of the housing 16 and the battery cell stack 20; however, other arrangements are also possible. For example, both the positive and negative electrode tabs 60, 62 may extend from the same end of the battery cells 44, i.e., from the first end 52 or the second end 54 of the battery cells 44. Alternatively, the positive and negative electrode tabs 60, 62 may extend from the top surfaces 56 of the battery cells 44 into the plenum 42 between the top surface 28 of the housing 16 and the top end 34 of the battery cell stack 20.

[0027] The battery cells 44 may be lithium-ion battery cells. As shown in the Fig. 1, Fig. 3 and Fig. For example, as shown in Figure 4, the battery cells 44 may be pouch-type lithium-ion battery cells. In other cases, the battery cells 44 may be prismatic or canned lithium-ion battery cells.

[0028] The optional partition walls 46 may be configured to help control the temperature of the battery cells 44 in the battery cell stack 20, compensate for volumetric changes in the battery cells 44, and prevent the propagation of thermal runaway through the battery cells 44 of the battery cell stack 20. The partition walls 46 may be sandwiched between adjacent groups of battery cells 44 in the battery cell stack 20 and have a lower end 70 in thermal contact with the bottom 30 of the housing and an opposite upper end 72 extending over the top surfaces 56 of the battery cells 44 toward the top surface 28 of the housing 16. In some cases, the partition walls 46 may have a laminate structure including one or more thermally conductive layers, a thermal barrier layer, and a compression layer (not shown).The thermally conductive layer is in thermal contact with the heat sink 38 and helps dissipate heat from adjacent battery cells 44 during operation of the battery 10. The thermal barrier layer helps prevent the propagation of thermal runaway temperatures and / or combustion reactions through the partition walls 46. The compression layer can help compensate for expansion, contraction, and other physical changes to which the battery cells 44 are subjected during operation of the battery 10 and can help maintain contact pressure between the facing surfaces of the battery cells 44.The partition walls 46 may be constructed and arranged within the battery cell stack 20 such that when thermal runaway is initiated in a first group of battery cells 44 positioned on a first side of one of the partition walls 46, the partition wall 46 helps prevent the thermal runaway from propagating from the first group of battery cells 44 to a second adjacent group of battery cells 44 on an opposite second side of the partition wall 46.

[0029] During assembly, the battery cells 44 of the battery cell stack 20 may be electrically coupled to a battery management system (BMS) 64, which may include one or more integrated circuits (ICs) configured to measure certain operating parameters of the battery cells 44 (e.g., cell voltage and / or temperature), control the operation of the battery cells 44 (e.g., charging and discharging), and / or couple the battery cells 44 to the electrical power supply 12 of the vehicle 14 and / or an external power source. As described in the Fig. 1 and Fig. 4, the battery management system 64 may be disposed within the interior 18 of the housing 16 in the gap 24 between the battery cell stack 20 and the sidewall 32 of the housing 16. Or, the battery management system 64 is disposed outside the housing 16 and supported by the top 28 or the sidewall 32 of the housing 16. In some cases, a portion of the battery management system 64 may be disposed within the interior 18 of the housing 16, and another portion of the battery management system 64 may extend outside the housing 16. The position of the battery management system 64 relative to the housing 16 is selected based on the orientation of the battery cells 44 within the housing 16 (and / or based on the position of the positive and negative electrode tabs 60, 62 relative to the top 28 and / or the sidewall 32 of the housing 16). As shown in Fig. 4, electrical connectors 66 are used to interconnect the positive and negative electrode tabs 60, 62 of the battery cells 44 in a series or parallel arrangement, for example, via a bus bar 68.

[0030] The fill material 22 is configured to help conduct heat away from the battery cells 44 during normal operation of the battery 10, and during a thermal runaway event, the fill material 22 is configured to prevent the propagation of thermal runaway through the battery cells 44 of the battery cell stack 20 and mitigate damage to other components of the battery 10. To accomplish this, the fill material 22 is comprised of a thermally conductive material that, when exposed to thermal runaway temperatures (e.g., temperatures greater than or equal to about 200°C), thermally decomposes to form a thermal and physical barrier that prevents the propagation of thermal runaway temperatures through the battery cells 44 of the battery cell stack 20 and through the surrounding components of the battery 10.For example, the fill material 22 thermally decomposes when exposed to thermal runaway temperatures to form a thermal and physical barrier that prevents convective, conductive, and / or radiative heat transfer between the battery cells 44 of the battery cell stack 20 and / or between various components of the battery 10.

[0031] As in Fig. 3, the fill material 22 may fill a region of the interior space 18 of the housing 16 defined by the plenum 42 extending between the top surface 28 of the housing 16 and the top end 34 of the battery cell stack 20 (above the top sides 56 of the battery cells 44 and above the top ends 72 of the partition walls 46). In this case, during normal operation of the battery 10, the fill material 22 may form a thermally conductive path between adjacent battery cells 44 and the top surface 28 of the housing 16, which may help reduce thermal gradients between the battery cells 44 and conduct heat away from the battery cells 44 via the top surface 28 of the housing 16.And during thermal runaway, the fill material 22 may thermally decompose and form a thermal and physical barrier over the top surfaces 56 of the battery cells 44 and over the top ends 72 of the partition walls 46 that prevents propagation of thermal runaway temperatures between adjacent groups of battery cells 44 on opposite sides of the partition walls 46.

[0032] As in Fig.4, the fill material 22 fills a region of the interior space 18 of the housing 16 defined by the gap 24 between the sidewall 32 of the housing 16 and the first and / or second ends 52, 54 of the battery cells 44. The fill material 22 surrounds the positive and negative electrode tabs 60, 62 of the battery cells 44 such that the positive and negative electrode tabs 60, 62 (and the electrical terminals 66) are completely enclosed by the fill material 22. Furthermore, the fill material 22 extends along the sidewall 32 of the housing 16 from the bottom 30 of the housing to or toward the top 28 of the housing 16.In this arrangement, the fill material 22 can provide a thermally conductive path between the positive and negative electrode tabs 60, 62 of the battery cells 44 and the bottom 30 of the housing 16 (and the heat sink 38) during normal operation of the battery 10, which can enhance heat transfer away from the positive and negative electrode tabs 60, 62 and reduce thermal gradients within the battery cells 44 during operation of the battery 10. In some cases, the fill material 22 can surround and encapsulate the bus bar 68, the battery management system 64, and / or other electrical components of the battery 10 disposed within the interior 18 of the housing 16 and electrically connected to the positive and / or negative electrode tabs 60, 62 of the battery cells 44.In this case, the filler material 22 may form a heat-conducting path between the bus bar 68, the battery management system 64 and / or the other electrical components and the heat sink 38 connected to the housing 16.

[0033] During a thermal runaway event, the fill material 22 thermally decomposes to form a thermal and physical barrier between adjacent positive and / or negative electrode tabs 60, 62 of the battery cells 44, preventing heat transfer between and around the electrode tabs 60, 62. Furthermore, during a thermal runaway event, the fill material 22 thermally decomposes to form a thermal and physical barrier between the positive and / or negative electrode tabs 60, 62 and the battery management system 64 located in the gap 24 between the battery cell stack 20 and the sidewall 32 of the housing 16.The formation of a thermal and physical barrier between the positive and / or negative electrode tabs 60, 62 of the battery cells 44 and the battery management system 64 during a thermal runaway event helps prevent heat transfer from the positive and / or negative electrode tabs 60, 62 to the battery management system 64, and also helps direct the exhaust gases generated by the battery cells 44 to the vent opening 29 in the top 28 of the housing 16 (rather than allowing the gases to escape through the battery management system 64 and / or through the sidewall 32 of the housing 16).

[0034] The fill material 22 has a composite structure including a thermally conductive particulate component dispersed within a polymeric matrix component. The polymeric matrix component may comprise a continuous monolithic three-dimensional network in which the particulate component is embedded or dispersed. The term "monolithic" refers to a three-dimensional structure that is not particulate. The particulate component imparts high thermal conductivity to the fill material 22 during normal operation of the battery 10, and the matrix component allows the fill material 22 to penetrate into the gap 24 and / or the plenum 42 in the housing 16 and imparts the ability to thermally decompose or char when exposed to thermal runaway temperatures to form a thermal and physical barrier that helps contain thermal runaway.The thermal runaway temperatures that can trigger thermal decomposition of the matrix component of the fill material 22 can include temperatures that exceed an upper operating temperature limit of the battery cells 44 of the battery 10, e.g., temperatures greater than or equal to about 200°C. The thermal runaway temperatures that can initiate thermal decomposition of the matrix component of the fill material 22 can be significantly lower than the temperatures that can be reached in the battery 10 during a thermal runaway event, e.g., temperatures greater than 900°C.

[0035] The polymeric matrix component may be porous, solid, or gelatinous and may comprise or consist essentially of a polymer, e.g., an organic polymer having a covalently bonded carbon backbone and / or an inorganic silicone polymer (polysiloxane) having a silicon-oxygen backbone. Examples of polymers include: epoxy resin, phenolic resin, polyester, polyurethane, urea-formaldehyde resin, polyethylene, polyethylene-vinyl acetate, polypropylene, polystyrene, polyvinyl chloride, polychloroprene, polyimide, polyamide, polylactic acid, poly(methyl methacrylate), silicone, natural rubber, ethylene-propylene-diene monomer (EPDM) rubber, styrene-butadiene rubber, and / or nitrile rubber. In embodiments where the polymeric matrix component is porous, the polymeric matrix component may have a porosity ranging from about 16% to about 50%.

[0036] The polymeric matrix component has a thermal conductivity of less than about 1 W / m·K. For example, the polymeric matrix component may have a thermal conductivity in the range of about 0.1 W / m·K to about 0.5 W / m·K.

[0037] The thermally conductive particle component provides the filler material 22 with a thermal conductivity of about 3 W / m·K. In some cases, the thermally conductive particle component may provide the filler material 22 with a thermal conductivity in the range of about 3 W / m·K to about 10 W / m·K.

[0038] The thermally conductive particle component may comprise less than 50% of the filler 22 by volume. For example, the thermally conductive particle component may comprise more than 5%, 10%, or 20% of the filler 22, less than 50%, 40%, or 30% of the filler 22, or between 5-50%, 10-40%, or 20-30% of the filler 22 by volume.

[0039] The thermally conductive particulate component is made of a ceramic-based material and may contain particles of alumina, silicon dioxide, titanium dioxide, zeolite, aluminum nitride, silicon carbide, aluminum oxide, aluminum nitride, boron nitride, silicon nitride and / or beryllium oxide.

[0040] The heat-conducting particulate component may consist of particles with an average particle diameter in the range of 0.2 micrometers to 100 micrometers.

[0041] The filler material 22 can be introduced into the interior 18 of the housing 16 after the complete or partial assembly of the battery 10. The filler material 22 can be introduced into the interior 18 of the housing 16, for example, by preparing a mixture of a liquid polymer precursor and particles of the thermally conductive particulate component. A gas can be generated in the liquid polymer precursor by mechanical, physical, and / or chemical foaming, which can then stabilize and solidify.

Claims

[1] A battery (10) comprising: a housing (16) having an inner surface (26) which at least partially defines an interior space (18) of the housing (16); a battery cell stack (20) arranged in the interior (18) of the housing (16) such that a gap (24) exists between the battery cell stack (20) and the inner surface (26) of the housing (16), wherein the battery cell stack (20) comprises: a first battery cell group with at least two adjacent battery cells (44); a second battery cell group with at least two adjacent battery cells (44); and a partition wall (46) physically separating the first battery cell group from the second battery cell group, wherein each of the battery cells (44) of the first battery cell group and the second battery cell group comprises an electrode assembly (48) sealed in a box (50) and a positive electrode tab and a negative electrode tab (60, 62) electrically coupled to the electrode assembly (48) and extending from the electrode assembly (48) outside the box (50), and wherein the positive electrode tabs and / or the negative electrode tabs (60, 62) of the battery cells (44) extend into the gap (24) between the battery cell stack (20) and the inner surface (26) of the housing (16); and a filler material (22) that fills the gap (24) and provides a heat-conducting path between the positive electrode tabs and / or the negative electrode tabs (60, 62) of the battery cells (44) and the inner surface (26) of the housing (16), wherein the filler material (22) is in direct physical contact with the positive electrode tabs and / or the negative electrode tabs (60, 62) of the battery cells (44) and with the inner surface (26) of the housing (16), wherein the filler material (22) fills a region of the interior space (18) of the housing (16) defined by a plenum (42) that extends between a top surface (28) of the housing (16) and an upper end (34) of the battery cell stack (20), above upper sides (56) of the battery cells (44) and above upper ends (72) of the partition walls (46), wherein the filler material (22) forms a heat-conducting path between adjacent battery cells (44) and the top surface (28) of the housing (16) during normal operation of the battery (10) to help reduce heat gradients between the battery cells (44) and to dissipate heat from the battery cells (44) via the top surface (28) of the housing (16), wherein the filler material (22) comprises a thermally conductive particulate component distributed in a polymeric matrix component, wherein the heat-conducting particulate component comprises particles of at least one of the substances selected from the group consisting of: aluminum oxide, silicon dioxide, titanium dioxide, zeolite, aluminum nitride, or silicon carbide, wherein the polymeric matrix component comprises an organic polymer and / or a polysiloxane, and wherein the polymeric matrix component is configured to thermally decompose at temperatures higher than an upper operating temperature of the battery cells (44) to form a thermal and physical barrier that prevents heat transfer between the first battery cell group and the second battery cell group across the gap (24). [2] The battery (10) of claim 1, wherein the polymeric matrix component is configured to thermally decompose at temperatures greater than or equal to 200°C to form a thermal and physical barrier that prevents heat transfer between a plurality of battery cells (44) of the battery cell stack (20). [3] The battery (10) of claim 1, wherein the polymeric matrix component has a thermal conductivity of less than 1 W / m·K, the thermally conductive particulate component has a thermal conductivity of more than 50 W / m·K, and the filler material (22) has a thermal conductivity in the range of 3 W / m·K to 10 W / m·K. [4] The battery (10) of claim 1, wherein the housing (16) is in thermal contact with a heat sink (38), and wherein the filler material (22) provides a thermally conductive path between the positive electrode tabs and the negative electrode tabs (60, 62) of the plurality of battery cells (44) and the heat sink (38). [5] Battery (10) according to claim 4, further comprising: a battery management system (64) with at least one integrated circuit, wherein the filler material (22) is arranged between the battery management system (64) and the positive electrode tabs and / or the negative electrode tabs (60, 62) of the plurality of battery cells (44), wherein the polymeric matrix component of the filler material (22) is configured to thermally decompose at temperatures greater than or equal to 200°C to provide thermal and to form a physical barrier that prevents exhaust gases released from the battery cells (44) from coming into direct physical or thermal contact with the battery management system (64), wherein the filler material (22) is in direct physical contact with the battery management system (64), and wherein the filler material (22) forms a heat-conducting path between the at least one integrated circuit of the battery management system (64) and the heat sink (38). [6] The battery (10) of claim 1, wherein the housing (16) has a top side (28), a bottom side (30), and a side wall (32) extending between the top side (28) and the bottom side (30) of the housing (16), wherein the top side (28), the bottom side (30), and the side wall (32) at least partially define the interior space (18) of the housing (16), wherein the battery cell stack (20) is arranged in the interior space (18) of the housing (16) such that the gap (24) extends between the battery cell stack (20) and the side wall (32) of the housing (16), and wherein the positive electrode tabs and / or the negative electrode tabs (60, 62) of the plurality of battery cells (44) extend into the gap (24) and are enclosed in the filler material (22).

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