Inverted U-shaped square cell stack geometry

Abstract

The square battery includes a square battery can having an upper region, a vertical Z-direction along a height of the square battery can, and a horizontal Y-direction along a width of the square battery can. A plurality of stacked battery layers are disposed inside the square battery can. The stacked cell layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction. The stacked cell layers have orthotropic thermal conductivity with high in-plane thermal conductivity in the in-plane direction and low lateral thermal conductivity in the lateral direction. The stacked battery layers are folded inside the square battery can in an inverted U-shaped geometry. The inverted U-shaped geometry is configured to provide longer thermal delay times and reduced peak temperatures in response to thermal runaway events occurring in adjacent battery cans.

Description

Technical Field

[0001] The present disclosure relates generally to electrochemical devices. More specifically, aspects of the present disclosure relate to lithium-ion batteries for use in electric motor vehicles and other electrically powered devices, such as electrically powered aircraft. Background Art

[0002] The motor vehicles currently produced, such as modern cars, are initially equipped with a powertrain that operates to drive the vehicle and provide power for the vehicle's onboard electronics. For example, in automotive applications, the vehicle powertrain is typically represented by a prime mover that transmits drive torque to the vehicle's final drive system (e.g., differential, axle, corner module, wheel, etc.) through an automatic or manually shifted power transmission. Automobiles have historically been powered by reciprocating piston internal combustion engine (ICE) components because they are easily available, relatively inexpensive, lightweight, and highly efficient overall. As some non-limiting examples, such engines include compression ignition (CI) diesel engines, spark ignition (SI) gasoline engines, two-stroke, four-stroke, and six-stroke architectures, and rotary engines. On the other hand, hybrid electric vehicles and all-electric vehicles (collectively referred to as "electrically powered vehicles") utilize alternative energy sources to drive the vehicle, thereby minimizing or eliminating reliance on fossil fuel-based engines to provide traction.

[0003] A full electric vehicle (FEV) – colloquially known as an “electric vehicle” – is an electrically driven vehicle configuration that completely omits the internal combustion engine and accompanying peripheral components from the powertrain system, instead relying on a rechargeable energy storage system (RESS) and traction motors for vehicle propulsion. The engine components, fuel supply system, and exhaust system of an ICE-based vehicle are replaced by a single or multiple traction motors, rechargeable battery tanks, and battery cooling and charging hardware in a battery-based FEV. In contrast, a hybrid electric vehicle (HEV) powertrain employs a variety of traction power sources to propel the vehicle, most commonly an internal combustion engine component operating in conjunction with a battery-powered or fuel tank-powered traction motor. Because hybrid electric vehicles derive their power from a source other than the engine, the HEV engine can be fully or partially shut down when the vehicle is driven by the electric motor.

[0004] High voltage (HV) electrical systems control the transfer of power between the traction motors and the rechargeable battery packs, providing the power required for operation of many hybrid electric and all-electric powertrains. To provide the power capacity and energy density required to propel the vehicle for a desired range at a desired speed, modern traction battery packs group multiple battery cans (e.g., 8-16+ cans / stack) into individual battery modules (e.g., 10-40+ modules / stack) that are electrically interconnected in series or parallel and mounted to the vehicle chassis, for example, via a battery pack housing or support tray. Located on the battery side of the HV electrical system is a front-end DC-DC power converter that is electrically connected to the traction battery pack to increase the voltage supply to the main DC bus and the DC-AC power inverter module (PIM). High frequency bulk capacitors may be arranged between the positive and negative terminals of the main DC bus to provide electrical stability and store supplemental electrical energy. A dedicated electronic battery control module (EBCM) controls the operation of the battery pack and traction motors through cooperative operation with the powertrain control module (PCM) and the power electronics components of each motor.

[0005] Battery arrays such as battery modules, battery packs, etc. typically include multiple battery cans relatively close to each other. Batteries can be generally divided into primary batteries and secondary batteries. Primary batteries, also called disposable batteries, are intended to be used until they are exhausted, after which they are simply replaced with new batteries. Secondary batteries, often called rechargeable batteries, use a specific chemical composition that allows such batteries to be repeatedly charged and reused, thus having economic, environmental and easy-to-use benefits compared to disposable batteries.

[0006] Rechargeable batteries are used to power a variety of items such as toys, consumer electronics, motor vehicles, and aircraft. The specific chemical composition of rechargeable batteries, such as lithium-ion cans, as well as external factors, can cause internal chemical reactions that generate large amounts of heat energy. This abnormal chemical reaction can cause the battery can to generate more heat than can be effectively dissipated. Exposure of the battery can to high temperatures for extended periods of time can cause a thermal runaway event in the battery can. As a result, a thermal runaway propagation (TRP) event that starts within a single can can cause heat to spread to adjacent cans in the battery array and result in a thermal runaway event that affects the entire battery pack and affects nearby temperature-sensitive components such as controllers, sensors, battery terminals, and connectors.

[0007] The individual cans of a lithium-ion battery pack can generate significant amounts of heat during charge and discharge cycles. This can heat load is primarily generated by exothermic chemical reactions and losses due to activation energy, chemical transport, and ion migration resistance. Within a lithium-ion battery, a series of exothermic and gas generating reactions can occur as the can temperature increases, which can push the battery components into an unstable state. If not controlled, such thermal events can lead to a more accelerated thermal state known as "thermal runaway" (TR) or "thermal runaway propagation" (TRP), in which the battery system is unable to return the internal battery components to normal operating temperatures. TRP events can damage the battery pack and melt internal components. Battery modules, which include multiple battery cans, can be supported by an actively cooled bottom cold plate to control the temperature during battery charge and discharge operations. Summary of the invention

[0008] The present disclosure teaches innovative stacking geometries for multiple internal layers of rechargeable batteries (e.g., lithium-ion batteries) contained inside a square battery can for an electric vehicle or other electric drive device. The improved battery pack geometry includes an inverted U-shaped configuration. When the battery undergoes a thermal runaway (TR) event, the upper half of the battery will exhibit very high temperatures (e.g., 800°C). The inverted U-shaped stacking geometry has high thermal conductivity in the horizontal direction near the upper area of ​​the battery can for better heat dissipation, while also providing higher thermal conductivity in the vertical direction near the bottom of the battery can for better heat dissipation through an attached actively cooled bottom cold plate. This innovative stacking geometry provides longer delay times (e.g., >1300 seconds) and reduced peak temperatures (e.g., <155°C) in response to TR events occurring in adjacent battery cans. This innovative stacking geometry also allows the thermal response barrier (TRB) layer to be significantly thinner (e.g., 50% thinner), thereby allowing for greater battery pack energy density and / or smaller battery pack size.

[0009] In one embodiment, the square battery includes a square battery can having an upper area, a vertical Z direction along the height of the square battery can, and a horizontal Y direction along the width of the square battery can. A plurality of stacked battery layers are arranged inside the square battery can. The stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction. The stacked battery layers have orthotropic thermal conductivity, which has a high in-plane thermal conductivity in the in-plane direction and a low lateral thermal conductivity in the lateral direction. The stacked battery layers are folded inside the square battery can in an inverted U-shaped geometry. The inverted U-shaped geometry is configured to provide a longer thermal delay time and a reduced peak temperature in response to a thermal runaway event occurring in an adjacent battery can.

[0010] Another embodiment relates to a square battery, comprising: a square battery can having a height / width aspect ratio greater than 1.5, which also has an upper region, a vertical Z direction along the height of the square battery can, and a horizontal Y direction along the width of the square battery can. A plurality of stacked battery layers are arranged inside the square battery can; wherein the stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction. The stacked battery layers have orthotropic thermal conductivity, which has high thermal conductivity in the in-plane direction and low thermal conductivity in the lateral direction. The stacked battery layers are arranged inside the square battery can in such a way that the thermal conductivity in the upper region of the square battery can is high in the horizontal Y direction (see Figure 3 ). The stacked battery layers are folded in an "inverted U" geometry within the prismatic battery can. For lithium-ion batteries, the ratio of the high in-plane thermal conductivity of the stacked battery layers divided by the low lateral thermal conductivity is typically greater than 10 (e.g., equal to about 13). The height / width aspect ratio of the prismatic battery can may be greater than about 3. The upper region of the prismatic battery can may have a height ranging from 10% to 20% of the total height of the prismatic battery can.

[0011] In another embodiment, the stacked battery layers include: a negative current collector layer, an anode electrode layer disposed adjacent to the negative current collector layer, a separator layer disposed adjacent to the anode electrode layer, a cathode electrode layer disposed adjacent to the separator layer; and a positive current collector layer disposed adjacent to the cathode electrode layer. The square battery may be a square lithium-ion battery. The negative current collector layer may be made of copper. The anode electrode layer may be graphite, lithium titanate, silicon / carbon, or tin / cobalt alloy, or a combination thereof. The separator layer may be a microporous polyolefin polymer, such as microporous polyethylene (PE), microporous polypropylene (PP), or microporous polyethylene terephthalate (PET), or a combination thereof. The cathode electrode layer may be a lithium metal oxide, LiCoO2 (LCO), LiMn2O4 (LMO), LiFePO4 (LFP), nickel manganese cobalt oxide (NMC) or nickel cobalt aluminum oxide (NCA) or a combination thereof. The positive current collector layer may be made of aluminum.

[0012] Another embodiment relates to a prismatic battery pack comprising: a first prismatic battery can; an adjacent second prismatic battery can; an actively cooled bottom cold plate disposed below the first and second prismatic battery cans; and a thermally responsive barrier (TRB) layer disposed between the first and second prismatic battery cans. In the event of a thermal runaway (TR) event in one of the prismatic battery cans, the TRB layer reduces heat conduction from the first prismatic battery can to the second (adjacent) prismatic battery can. Each prismatic battery can may include stacked battery layers folded (i.e., wound) in an inverted U-shaped geometry. When an inverted U-shaped geometry is used inside each prismatic battery can, the time required to raise the temperature of the adjacent prismatic can after the thermal runaway event begins is longer.

[0013] Another embodiment relates to an electric vehicle, comprising: a body having a passenger compartment; a plurality of wheels attached to the body; a traction motor attached to the body, operable to drive one or more of the plurality of wheels to propel the electric vehicle; and a traction battery pack attached to the body and electrically connected to the traction motor. The traction battery pack comprises a plurality of prismatic battery cans arranged in parallel rows. Each prismatic battery can comprises: a prismatic battery can having a height / width aspect ratio greater than 1.5, preferably greater than 3. Each prismatic battery can comprises an upper region, a vertical Z direction along the height of the prismatic battery can, and a horizontal Y direction along the width of the prismatic battery can. A plurality of stacked battery layers are arranged inside the prismatic battery can; wherein the stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction. The stacked battery layers have orthotropic thermal conductivity, having high thermal conductivity in the in-plane direction and low thermal conductivity in the lateral direction. The stacked battery layers are arranged inside the prismatic battery can in such a manner that the thermal conductivity in the upper region of the prismatic battery can is high in the horizontal Y direction. The stacked battery layers are configured (i.e., folded) in an "inverted U" geometry inside the prismatic battery can. The height / width ratio of the prismatic battery can may be greater than 3, and the ratio of the high in-plane thermal conductivity divided by the low lateral thermal conductivity of the plurality of stacked battery layers may be greater than 10. The prismatic battery pack may include prismatic lithium-ion batteries.

[0014] The present invention provides the following technical solutions:

[0015] 1. A square battery, comprising:

[0016] A square battery can including an upper region, a vertical Z direction along the height of the square battery can, and a horizontal Y direction along the width of the square battery can; and

[0017] A plurality of stacked battery layers disposed inside a square battery can;

[0018] wherein the plurality of stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction;

[0019] wherein the plurality of stacked battery layers have orthotropic thermal conductivity having an in-plane thermal conductivity in an in-plane direction and a lateral thermal conductivity in a lateral direction;

[0020] Among them, the in-plane thermal conductivity is greater than the transverse thermal conductivity;

[0021] wherein the plurality of stacked battery layers are arranged in an inverted U-shaped geometry inside a square battery can; and

[0022] Among them, the in-plane thermal conductivity in the horizontal Y direction in the upper region of the square battery can is higher than the lateral thermal conductivity in the vertical Z direction.

[0023] 2. A square battery according to Option 1, wherein the ratio of the in-plane thermal conductivity of the multiple stacked battery layers divided by the lateral thermal conductivity is greater than about 10.0.

[0024] 3. The square battery according to claim 1, wherein the aspect ratio of the height of the square battery can divided by the width of the square battery can is greater than about 1.5.

[0025] 4. The square battery according to claim 3, wherein the aspect ratio of the height of the square battery can divided by the width of the square battery can is greater than about 3.0.

[0026] 5. The square battery according to claim 1, wherein the height of the upper region of the square battery can ranges from 10% to 20% of the total height of the square battery can.

[0027] 6. A square battery according to claim 1, wherein the plurality of stacked battery layers comprises a negative electrode current collector layer;

[0028] an anode electrode layer disposed adjacent to the negative electrode current collector layer;

[0029] a diaphragm layer disposed adjacent to the anode electrode layer;

[0030] a cathode electrode layer, the cathode electrode layer being disposed adjacent to the separator layer and opposite to the anode electrode layer; and

[0031] A positive electrode current collector layer is disposed adjacent to the cathode electrode layer.

[0032] 7. The square battery according to claim 6,

[0033] Among them, the square battery can includes lithium-ion batteries;

[0034] wherein the negative electrode current collector layer comprises copper;

[0035] Wherein, the anode electrode layer comprises a material selected from graphite, lithium titanate, silicon / carbon, or tin / cobalt alloy and combinations thereof;

[0036] wherein the diaphragm layer comprises a microporous polyolefin polymer selected from microporous polyethylene (PE), microporous polypropylene (PP) or microporous polyethylene terephthalate (PET) and combinations thereof;

[0037] wherein the cathode electrode layer comprises a material selected from lithium metal oxide, LiCoO2 (LCO), LiMn2O4 (LMO), LiFePO4 (LFP), nickel manganese cobalt oxide (NMC) or nickel cobalt aluminum oxide (NCA) and combinations thereof; and

[0038] The positive electrode current collector layer comprises aluminum.

[0039] 8. A square battery pack comprising:

[0040] The first square battery can;

[0041] a second square battery can disposed adjacent to the first square battery can;

[0042] an actively cooled bottom cold plate disposed below the first and second prismatic battery cans; and

[0043] A thermally responsive barrier (TRB) layer is disposed between the first prismatic battery can and the second prismatic battery can, wherein the TRB layer is configured to reduce heat conduction from the first prismatic battery can to the second prismatic battery can.

[0044] 9. The square battery pack according to solution 8,

[0045] wherein the first square battery can comprises a first plurality of stacked battery layers arranged in an inverted U-shaped geometry inside the first square battery can; and

[0046] Therein, the second square battery can includes a second plurality of stacked battery layers arranged in an inverted U-shaped geometry inside the second square battery can.

[0047] 10. A square battery pack according to Option 9, wherein the second square can is configured to have a thermal response time greater than about 1300 seconds to reach a peak temperature not exceeding about 155°C after a thermal runaway (TR) event occurs in an adjacent first square battery can.

[0048] 11. The square battery pack according to claim 9, wherein the first plurality of stacked battery layers comprises

[0049] Anode current collector layer;

[0050] an anode electrode layer disposed adjacent to the negative electrode current collector layer;

[0051] a diaphragm layer disposed adjacent to the anode electrode layer;

[0052] a cathode electrode layer disposed opposite the anode electrode layer and adjacent to the separator layer; and

[0053] A positive electrode current collector layer is disposed adjacent to the cathode electrode layer.

[0054] 12. An electric vehicle comprising:

[0055] a vehicle body having a passenger compartment;

[0056] a plurality of wheels attached to the vehicle body;

[0057] a traction motor attached to the vehicle body and operable to drive one or more of the plurality of wheels to propel the electric vehicle; and

[0058] a traction battery pack attached to the vehicle body and electrically connected to the traction motor;

[0059] Among them, the traction battery pack includes a square battery tank;

[0060] Among them, the square battery cans include:

[0061] Upper area;

[0062] A vertical Z direction oriented along the height of the square battery can;

[0063] A horizontal Y direction oriented along the width of the prismatic battery can; and

[0064] A plurality of stacked battery layers disposed inside a square battery can;

[0065] wherein the plurality of stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction;

[0066] wherein the plurality of stacked battery layers have orthotropic thermal conductivity having an in-plane thermal conductivity in an in-plane direction and a lateral thermal conductivity in a lateral direction;

[0067] Among them, the in-plane thermal conductivity is greater than the transverse thermal conductivity;

[0068] wherein the plurality of stacked battery layers are arranged in an inverted U-shaped geometry inside a square battery can;

[0069] Among them, the in-plane thermal conductivity in the horizontal Y direction in the upper region of the square battery can is higher than the lateral thermal conductivity in the vertical Z direction.

[0070] 13. An electric vehicle according to embodiment 12, wherein the ratio of the in-plane thermal conductivity of the plurality of stacked battery layers divided by the lateral thermal conductivity is greater than about 10.0.

[0071] 14. An electric vehicle according to Option 12, wherein the aspect ratio of the height of the square battery can divided by the width of the square battery can is greater than about 1.5.

[0072] 15. An electric vehicle according to Option 14, wherein the aspect ratio of the height of the square battery can divided by the width is greater than about 3.0.

[0073] 16. An electric vehicle according to Option 12, wherein the square battery can includes a lithium-ion battery.

[0074] 17. The electric vehicle of claim 12, wherein the traction battery pack is disposed on top of an actively cooled bottom cold plate.

[0075] 18. The electric vehicle according to claim 12, wherein the height of the upper region of the square battery can ranges from 10% to 20% of the total height of the square battery can.

[0076] 19. The electric vehicle according to solution 12 further comprises:

[0077] a second square battery can disposed adjacent to the first square battery can;

[0078] an actively cooled bottom cold plate disposed beneath both the first prismatic battery can and the second prismatic battery can; and

[0079] A thermally responsive barrier (TRB) layer is disposed between the first prismatic battery can and the second prismatic battery can, the thermally responsive barrier layer being configured to reduce heat conduction from the first prismatic battery can to the second prismatic battery can.

[0080] 20. An electric vehicle according to Option 12, wherein the second prismatic battery can is configured to have a thermal response time greater than about 1300 seconds to reach a peak temperature less than about 155°C after a thermal runaway (TR) event occurs in the first prismatic battery can.

[0081] The above summary does not represent every embodiment or every aspect of the present disclosure. On the contrary, the foregoing summary only provides an outline of some novel concepts and features set forth herein. When combined with the accompanying drawings and the appended claims, the above-mentioned features and advantages of the present disclosure and other features and accompanying advantages will become apparent from the following detailed description of the examples shown and the representative modes for performing the present disclosure. In addition, the present disclosure expressly includes any and all combinations and sub-combinations of the elements and features presented above and below. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 A schematic perspective view of an example of an electric vehicle having a lithium-ion battery pack according to the present disclosure is shown.

[0083] Figure 2 A schematic cross-sectional view of an example of a basic lithium-ion battery stack including five stacked battery layers according to the present disclosure is shown.

[0084] Figure 3 A three-dimensional perspective view of an example of a pair of prismatic battery cans "A" and "B" arranged side by side with a thermally responsive barrier disposed between cans "A" and "B" and both cans resting on a bottom cold plate in accordance with the present disclosure is shown.

[0085] Figure 4A schematic three-dimensional perspective view of a pair of prismatic battery cans "A" and "B" arranged side by side according to the present disclosure is shown, wherein a thermally responsive barrier (TRB) is disposed between cans "A" and "B", and both cans are located on an actively cooled bottom cold plate.

[0086] Figure 5A A schematic two-dimensional cross-sectional side view of an example of a prismatic battery can according to the present disclosure is shown, wherein stacked battery layers are arranged vertically along the Z direction (ie, a “Z stack”).

[0087] Figure 5B A schematic two-dimensional cross-sectional side view of an example of a prismatic battery can according to the present disclosure is shown, wherein the stacked battery layers are folded into a "Jelly-Roll" geometry.

[0088] Figure 5C A schematic two-dimensional cross-sectional side view of an example of a prismatic battery can according to the present disclosure is shown, wherein the stacked battery layers are folded into an “inverted U” geometry.

[0089] Fig. 6A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can according to the present disclosure is shown, wherein stacked battery layers are arranged vertically along the Z direction (“Z-stack”).

[0090] Figure 6B It is shown that according to the present disclosure Fig. 6A 2D contour plot of an example of the calculated temperature of Li-ion tank “B” 500 seconds after the start of the thermal runaway propagation event in the adjacent tank “A” for the Z-stack layer geometry shown in FIG.

[0091] Fig. 7A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can according to the present disclosure is shown, wherein the stacked battery layers are arranged horizontally along the Y direction (“H-stack”).

[0092] Figure 7B It is shown that according to the present disclosure Fig. 7A 2D contour plot of an example of the calculated temperature of Li-ion tank “B” 500 seconds after the start of the thermal runaway propagation event in the adjacent tank “A” for the H-stack layer geometry shown in FIG.

[0093] Fig. 8A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can according to the present disclosure is shown, wherein the stacked battery layers are folded into a "jelly-roll" geometry.

[0094] Figure 8B It is shown that according to the present disclosure Fig. 8A2D contour plot of an example of the calculated temperature of Li-ion tank “B” 500 seconds after the start of the thermal runaway propagation event in the adjacent tank “A” for the coil core geometry shown in FIG.

[0095] Fig. 9A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can according to the present disclosure is shown, wherein the stacked battery layers are folded into an “inverted U” geometry.

[0096] Fig. 9B It is shown that according to the present disclosure Fig. 9A 2D contour plot of an example of the calculated temperature of Li-ion tank “B” 500 seconds after the start of the thermal runaway propagation event in the adjacent tank “A” for the inverted U-shaped layer geometry shown in FIG.

[0097] Fig. 10A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can according to the present disclosure is shown, wherein the stacked battery layers are folded into a "U-shaped" geometry.

[0098] Fig. 10B It is shown that according to the present disclosure Fig. 10A 2D contour plot of an example of the calculated temperature of Li-ion tank “B” 500 seconds after the start of the thermal runaway propagation event in the adjacent tank “A” for the U-shaped layer geometry shown in FIG.

[0099] Fig.11A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can according to the present disclosure is shown, wherein the stacked battery layers are folded into an “S-shaped” geometry.

[0100] Fig. 11B It is shown that according to the present disclosure Fig.11A 2D contour plot of an example of the calculated temperature of Li-ion tank “B” 500 seconds after the start of the thermal runaway propagation event in the adjacent tank “A” for the S-shaped layer geometry shown in FIG.

[0101] Fig.12 An example of a summary graph of calculated peak temperatures (C) and thermal runaway initiation times (s) for six different lithium-ion prismatic can layer winding designs of adjacent prismatic battery cans "B" from the results table shown in Table 2 according to the present disclosure is shown. DETAILED DESCRIPTION

[0102] The present disclosure may take many different forms of embodiments. Representative embodiments of the present disclosure are shown in the accompanying drawings and will be described in detail herein, and it should be understood that these embodiments are provided as examples of the disclosed principles, rather than limitations on the broad aspects of the present disclosure. In this regard, elements and limitations such as those described in the abstract, introduction, overview, and detailed description sections, but not explicitly set forth in the claims, should not be incorporated into the claims individually or collectively by implication, inference, or otherwise.

[0103] For the purpose of this detailed description, unless expressly denied: the singular includes the plural and vice versa; the words "and" and "or" are both conjunctions and disjunctions; the words "any" and "all" mean "any and all"; the words "include", "contain", "include", "have" and the like all mean "including but not limited to". In addition, approximate words such as "approximately", "almost", "substantially", "roughly", "approximately" and the like may be used herein, for example, in the sense of "at, close to or nearly at..." or "within 0-5% of..." or "within an acceptable manufacturing tolerance" or any logical combination thereof.

[0104] Unless specifically indicated from the context, as used herein, the term "about" should be understood to be within the normal tolerance range in the art, such as within 2 standard deviations of the mean. "About" can be understood to be within 10%, 5%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the value. "About" can also be understood to imply the exact value specified. Unless the context clearly indicates otherwise, the numerical values ​​provided herein are modified by the term "about".

[0105] Finally, directional adjectives and adverbs, such as front, rear, inboard, outboard, starboard, port, vertical, horizontal, upward, downward, front, rear, left, right, etc., may be used with respect to a motor vehicle, such as the forward direction of travel of the motor vehicle when the vehicle is operably oriented on a horizontal running surface. The phrases "wrap-around design" and "battery stack geometry" may be used interchangeably. The phrases "battery can" and "square can" may be used interchangeably.

[0106] The present disclosure proposes an innovative battery stack geometry (i.e., a winding design) for orienting multiple internal layers of rechargeable batteries (e.g., lithium-ion batteries) inside a square battery can for electric vehicles and other devices. The improved battery stack geometry includes an inverted U-shaped configuration. With the help of a bottom cold plate, when battery can "A" experiences a thermal runaway propagation (TRP) event, the upper half of the adjacent battery can "B" displays a hot spot (150C to 190C). The inverted U-shaped geometry can achieve high thermal conductivity in the horizontal direction near the upper area of ​​the battery can for better heat dissipation, while also providing higher thermal conductivity in the vertical direction near the bottom of the battery can for better heat dissipation through the bottom cold plate. This innovative stacking geometry provides a longer thermal response time (e.g., >1350s) and a reduced peak temperature (e.g., <155°C) after a TR event occurs in the adjacent battery can "A", both of which are highly desirable results.

[0107] Figure 1 A schematic perspective view of an example of an electric vehicle 1 having a battery pack 4 according to the present disclosure is shown. The electric vehicle 1 includes a body 2, a plurality of wheels 3, 3', etc. attached to the body 2, and a battery pack 4 located within the electric vehicle 1. The electric vehicle 1 also includes one or more traction motors 13 attached to the body 2, which are operable to drive one or more of the wheels 3, 3', etc. to propel the electric vehicle 1. The battery pack 4 is physically attached to the body 2 and electrically connected to the traction motor 13 with a cable 15.

[0108] Figure 2 A schematic cross-sectional view of an example of a lithium-ion battery stack including five stacked battery layers according to the present disclosure is shown. The five stacked battery layers of the lithium-ion battery can 11 include: a negative current collector layer 5, an anode electrode layer 6 disposed adjacent to the negative current collector layer 5, a separator layer 7 disposed adjacent to the anode electrode layer 6, a cathode electrode layer 8 disposed opposite to the anode electrode layer 5 and adjacent to the separator layer 7, and a positive current collector layer 9 disposed adjacent to the cathode electrode layer 8. The negative current collector layer 5 may include a copper sheet. The anode electrode layer 6 may include a material selected from the following: graphite, lithium titanate, silicon / carbon, or tin / cobalt alloy, and combinations thereof. The separator layer 7 may include a microporous polyolefin polymer selected from the following: microporous polyethylene (PE), microporous polypropylene (PP) or microporous polyethylene terephthalate (PET) and combinations thereof. The cathode electrode layer 8 may include a compound selected from the following: lithium metal oxide, LiCoO2 (LCO), LiMn2O4 (LMO), LiFePO4 (LFP), nickel manganese cobalt oxide (NMC), or nickel cobalt aluminum oxide (NCA) and combinations thereof. Finally, in some embodiments, the positive current collector layer 9 may include aluminum. The five stacked battery layers may be contained in a sealed square battery can (i.e., housing) with positive and negative tabs protruding from the top of the can.

[0109] Figure 3 A three-dimensional perspective view of an example of a first prismatic battery can "A" 10 and an adjacent second prismatic battery can "B" 12 arranged side by side according to the present disclosure is shown, wherein a thermally responsive barrier (TRB) layer 22 is disposed between the battery can "A" (10) and the battery can "B" (12). The prismatic battery cans 10 and 12 are supported by an actively cooled bottom cold plate 16. A positive electrode 14 and a negative electrode 14' are located on top of the prismatic battery cans 10 and 12.

[0110] Figure 4 A schematic three-dimensional perspective view of a pair of prismatic battery cans "A" (10) and "B" (12) arranged side by side is shown, wherein a thermal response barrier (TRB) 22 is disposed between the first can "A" and the second can "B", both cans being supported by an actively cooled bottom cold plate 16 in accordance with the present disclosure. The figure also shows an example of a finite volume calculated color-coded temperature contour plot of the temperature distribution through each of the prismatic battery cans 10 and 12, starting at time = 0, in response to a thermal runaway propagation (TRP) overheating event in the first prismatic battery can "A" (can 10). Figure 4 The left-hand side graph of shows that the peak temperature of the thermal runaway tank "A" has reached a maximum of 800°C (enough to melt aluminum). However, the peak temperature of the adjacent tank "B" (battery tank 12) only reaches 160°C, which is mainly due to the thermal insulation effect of the TRB layer 22. The TRB layer 22 can be made of a material with low thermal conductivity and a high melting point (e.g., a porous ceramic layer). The thickness of the TRB layer 22 can be 1-3mm. Note that the storage energy density of the battery pack increases as the thickness of the TRB layer 22 decreases.

[0111] Figure 5A A schematic two-dimensional cross-sectional side view of an example of a square battery can 12 according to the present disclosure is shown, wherein the stacked battery layers 18 are arranged vertically along the Z direction (i.e., "Z-stacked"). This Z-shaped stacking geometry 22 is used in lithium-ion batteries for electric vehicles. The square battery can 12 can be, for example, 90 mm high by 25 mm wide; and can have a height / width ratio greater than about 1.5, preferably greater than about 3.0. The battery can 12 has a vertical Z direction in the vertical direction and a horizontal Y direction in the horizontal direction.

[0112] Figure 5BA schematic two-dimensional cross-sectional side view of an example of a square battery can 12 according to the present disclosure is shown, in which the stacked battery layers 18 are folded into a "roll core" geometry. In this configuration, the stacked battery layers 18 are folded vertically along the Z direction in the middle 22 of the battery can 12. However, the stacked battery layers 18 are folded over each other at the top region 20 and the bottom region 20' of the battery can 12, respectively. This configuration defines a "roll core" geometry. The stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction; and the stacked battery layers have an orthotropic thermal conductivity, which has a high thermal conductivity in the in-plane direction (e.g., 18.4 WmK for lithium-ion batteries) and a low thermal conductivity in the lateral direction (e.g., 1.4 W / mK for lithium-ion batteries). The ratio of high thermal conductivity / low thermal conductivity of lithium-ion batteries is greater than about 10 (e.g., 13). Multiple stacked battery layers 18 are folded inside the square battery can 12 in such a way that the thermal conductivity in both the upper region 20 and the lower region 20' of the square battery can 12 is high in the horizontal Y direction. In the middle region 22 of the battery can 12, the thermal conductivity is high in the in-plane Z direction and low in the lateral Y direction. The upper region 20 and the lower region 20' of the square battery can 12 have a vertical height (e.g., 12.5 mm) from 10% to 20% of the total vertical height (e.g., 90 mm) of the square battery can 12. This configuration defines a "core" winding geometry.

[0113] Figure 5C A schematic two-dimensional cross-sectional side view of an example of a square battery can according to the present disclosure is shown, in which the stacked battery layers are folded into an "inverted U" geometry. In this configuration, the stacked battery layers 18 are arranged vertically along the Z direction in the middle to bottom region 22 of the battery can 12. However, the stacked battery layers 18 are folded over each other in the upper region 20 of the battery can 12. This configuration defines an "inverted U" geometry. The stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction. The stacked battery layers have orthotropic thermal conductivity, which has high thermal conductivity in the in-plane direction (e.g., 18.4 WmK for lithium-ion batteries) and low thermal conductivity in the lateral direction (e.g., 1.4 W / mK for lithium-ion batteries). The ratio of high thermal conductivity / low thermal conductivity of lithium-ion batteries is greater than about 10 (e.g., 13). The plurality of stacked battery layers 18 are folded inside the square battery can 12 in such a manner that the thermal conductivity in the upper region 20 of the square battery can 12 is high in the horizontal Y direction. In the middle to bottom region 22 of the battery can 12, the thermal conductivity is high in the in-plane Z direction and low in the lateral Y direction. The upper region 20 of the square battery can 12 has a height (e.g., 12.5 mm) of from 10% to 20% of the total height (e.g., 90 mm) of the square battery can 12.

[0114] Table 1 shows the orthotropic thermal conductivity values ​​(k x , k y , k z In the middle region 22 (see Figure 5B and 5C ), the thermal conductivity of the stacked battery layer 18 is high in the in-plane X direction and high in the in-plane Z direction (i.e., parallel to the in-plane direction of the battery layer 18). However, the thermal conductivity in the lateral Y direction (i.e., perpendicular to the in-plane direction of the stacked battery layer 18) is very low (e.g., <10%). Figure 5C In the upper region 20, the in-plane direction of the battery layer 18 is oriented parallel to the Y direction, which makes the Y-direction thermal conductivity k y and high in the upper region 20. Note that the ratio of the high in-plane thermal conductivity to the low lateral thermal conductivity is greater than about 10.0 (eg, 13.0).

[0115] Table 1 Orthotropic thermal conductivity (W / mK)

[0116]

[0117] Fig. 6A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can 12 according to the present disclosure is shown, with stacked battery layers 18 arranged vertically along the Z direction (“Z-stack”).

[0118] Figure 6B It is shown that according to the present disclosure Fig. 6A 2D contour plot of an example of the calculated temperature of a lithium-ion tank "B" 500 seconds after the start of a thermal runaway propagation event in an adjacent tank "A" for the Z stack layer geometry shown in . The contour plot shows the finite volume calculation results of the transient thermal response of the mid-plane of tank "B" adjacent to tank "A" (tank "A" is experiencing a thermal runaway (TR) event, starting at time = 0). In this example, at time = 500s, the peak temperature of tank "B" (12) is equal to 160C. The temperature at the bottom of tank "B" is equal to 55C (due to the bottom cold plate 16).

[0119] Fig. 7A A schematic two-dimensional cross-sectional side view of an example of a prismatic battery can 12 according to the present disclosure is shown, wherein stacked battery layers 18 are arranged horizontally along the Y direction (“H-stacked”).

[0120] Figure 7B It is shown that according to the present disclosure Fig. 7A2D contour plot of an example of the calculated temperature of a lithium-ion tank "B" 500 seconds after the start of a thermal runaway propagation event in an adjacent tank "A" for an "H-stack" layer geometry shown. The contour plot shows the finite volume calculation results of the transient thermal response of the mid-plane of tank "B" adjacent to tank "A" (tank "A" is experiencing a thermal runaway propagation (TRP) event, starting at time = 0). In this example, at time = 500s, the peak temperature of tank "B" (12) is equal to 185C. The temperature at the bottom of tank "B" is equal to 55C (due to the bottom cold plate). The higher peak temperature in this example is due to the low thermal conductivity of the H-stack geometry in the Z direction.

[0121] Fig. 8A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can 12 according to the present disclosure is shown, wherein the stacked battery layers 18 are folded into a “jelly-roll” geometry.

[0122] Figure 8B It is shown that according to the present disclosure Fig. 8A 2D contour plot of an example of the calculated temperature of a lithium-ion tank "B" 500 seconds after the start of a thermal runaway propagation event in an adjacent tank "A" for the roll core layer geometry shown in . The contour plot shows the finite volume calculation results of the transient thermal response of the mid-plane of tank "B" adjacent to tank "A" (tank "A" is experiencing a thermal runaway (TR) event, starting at time = 0). In this example, at time = 500s, the peak temperature of tank "B" (12) is equal to 159C. The temperature at the bottom of tank "B" is equal to 55C (due to the bottom cold plate). The lower peak temperature in this example is due to the high thermal conductivity of the roll core geometry in the Y direction.

[0123] Fig. 9A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can 12 according to the present disclosure is shown, wherein the stacked battery layers 18 are folded into an “inverted U” geometry.

[0124] Fig. 9B It is shown that according to the present disclosure Fig. 9A A 2D contour plot of an example of the calculated temperature of a lithium-ion tank "B" 500 seconds after the start of a thermal runaway propagation event in an adjacent tank "A" for an inverted U-shaped layer geometry shown. The contour plot shows the finite volume calculation results of the transient thermal response of the mid-plane of tank "B" adjacent to tank "A" (tank "A" is experiencing a thermal runaway propagation (TRP) event, starting at time = 0). In this example, at time = 500s, the peak temperature of tank "B" (12) is equal to 154C. The temperature at the bottom of tank "B" is equal to 55C (due to the bottom cold plate). The lower peak temperature in this example is due to the high thermal conductivity in the Y direction at the top of the inverted U-shaped geometry.

[0125] Fig. 10A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can 12 according to the present disclosure is shown, wherein the stacked battery layers 18 are folded into a "U-shaped" geometry.

[0126] Fig. 10B It is shown that according to the present disclosure Fig. 10A 2D contour plot of an example of the calculated temperature of a lithium-ion tank "B" 500 seconds after the start of a thermal runaway event in an adjacent tank "A" for the U-shaped layer geometry shown in . The figure shows the finite volume calculation results of the transient thermal response of the mid-plane of tank "B" adjacent to tank "A" (which is experiencing a thermal runaway (TR) event, starting at time = 0). In this example, at time = 500s, the peak temperature of tank "B" (12) is equal to 165C. The temperature at the bottom of tank "B" is equal to 55C (due to the bottom cold plate).

[0127] Fig.11A A schematic two-dimensional cross-sectional side view of an example of a single prismatic battery can 12 according to the present disclosure is shown, wherein the stacked battery layers 18 are folded into an "S-shaped" geometry.

[0128] Fig. 11B It is shown that according to the present disclosure Fig.11A 2D contour plot of an example of the calculated temperature of a lithium-ion tank "B" 500 seconds after the start of a thermal runaway event in an adjacent tank "A" for the S-shaped layer geometry shown in . The figure shows the finite volume calculation results of the transient thermal response of the mid-plane of tank "B" adjacent to tank "A" (which is experiencing a thermal runaway (TR) event, starting at time = 0). In this example, at time = 500s, the peak temperature of tank "B" (12) is equal to 166C. The temperature at the bottom of tank "B" is equal to 55C (due to the bottom cold plate).

[0129] In accordance with the present disclosure, Table 2 summarizes the calculated peak temperatures and thermal response times to reach peak temperatures for the six different stacked lithium-ion battery layer geometries shown in Figures 6-11. The best performing winding design is the "inverted U" stacking geometry, which has the lowest peak temperature (154C) and the longest response time (1360 seconds), which is 100% longer than the thermal response time of the worst tank H stacking design. The worst battery design is the H stacking geometry, which has a higher peak temperature of 185C and a shorter thermal response time of 675 seconds. Longer thermal response times are desirable because it provides more time for the battery pack and support system to react to TRP events.

[0130] Table 2 Summary of calculated temperatures and thermal response times

[0131]

[0132] Fig.12 An example of a summary graph of calculated peak temperatures (C) and thermal response times (seconds) for six different lithium-ion can layer winding designs (as shown in FIGS. 7-12 ) for adjacent battery cans “B” according to the present disclosure, taken from the results table shown in Table 2. Each data point corresponds to the following winding designs: H-stack (30); U-shape (32); S-shape (34); Z-stack (36); Jelly Bean (38); and Inverted U-shape (40). Fig.12 The graph shown in FIG. 4 has thermal response time (seconds) on the x-axis 42 and peak temperature (C) on the y-axis 44. The worst performing winding design is the H stack geometry 30, which has a high peak temperature of 185C and a short thermal response time of 675 seconds. The best performing winding design is the inverted U geometry 40, which has a low peak temperature of 154C and a much longer thermal response time of 1360 seconds.

[0133] For the bottom cold plate module design, the inverted U-shaped geometry has the lowest peak temperature without adversely affecting the cold plate heat removal due to better heat dissipation near the upper region 20. This results in a significant increase in the thermal response time of the adjacent battery cans compared to the Z-stack and core-wound geometries.

Claims

1. A square battery, comprising: A square battery can including an upper region, a vertical Z direction along the height of the square battery can, and a horizontal Y direction along the width of the square battery can; and A plurality of stacked battery layers disposed inside a square battery can; wherein the plurality of stacked battery layers have an in-plane direction and a lateral direction perpendicular to the in-plane direction; wherein the plurality of stacked battery layers have orthotropic thermal conductivity having an in-plane thermal conductivity in an in-plane direction and a lateral thermal conductivity in a lateral direction; Among them, the in-plane thermal conductivity is greater than the transverse thermal conductivity; wherein the plurality of stacked battery layers are arranged in an inverted U-shaped geometry inside a square battery can; and Among them, the in-plane thermal conductivity in the horizontal Y direction in the upper region of the square battery can is higher than the lateral thermal conductivity in the vertical Z direction. 2 . The square battery of claim 1 , wherein a ratio of the in-plane thermal conductivity divided by the lateral thermal conductivity of the plurality of stacked battery layers is greater than 10. 3 . 3 . The square battery according to claim 1 , wherein an aspect ratio of the height of the square battery can divided by the width of the square battery can is greater than 1.

5. 4 . The square battery according to claim 3 , wherein an aspect ratio of the height of the square battery can divided by the width of the square battery can is greater than 3.

5. The square battery according to claim 1, wherein: The height of the upper region of the square battery can ranges from 10% to 20% of the total height of the square battery can.

6. The square battery according to claim 1, wherein the plurality of stacked battery layers comprises Anode current collector layer; an anode electrode layer disposed adjacent to the negative electrode current collector layer; a diaphragm layer disposed adjacent to the anode electrode layer; a cathode electrode layer, the cathode electrode layer being disposed adjacent to the separator layer and opposite to the anode electrode layer; and A positive electrode current collector layer is disposed adjacent to the cathode electrode layer.

7. The square battery according to claim 6, in, The prismatic battery can includes lithium-ion batteries; wherein the negative electrode current collector layer comprises copper; Wherein, the anode electrode layer comprises a material selected from graphite, lithium titanate, silicon / carbon, or tin / cobalt alloy and combinations thereof; wherein the diaphragm layer comprises a microporous polyolefin polymer selected from microporous polyethylene (PE), microporous polypropylene (PP) or microporous polyethylene terephthalate (PET) and combinations thereof; wherein the cathode electrode layer comprises a material selected from lithium metal oxide, LiCoO2 (LCO), LiMn2O4 (LMO), LiFePO4 (LFP), nickel manganese cobalt oxide (NMC) or nickel cobalt aluminum oxide (NCA) and combinations thereof; and The positive electrode current collector layer comprises aluminum.

8. A square battery pack comprising: The first square battery can; a second square battery can disposed adjacent to the first square battery can; an actively cooled bottom cold plate disposed below the first and second prismatic battery cans; and A thermally responsive barrier (TRB) layer is disposed between the first prismatic battery can and the second prismatic battery can, wherein the TRB layer is configured to reduce heat conduction from the first prismatic battery can to the second prismatic battery can.

9. The square battery pack according to claim 8, in, The first prismatic battery can includes a first plurality of stacked battery layers arranged in an inverted U-shaped geometry within the first prismatic battery can; and Therein, the second square battery can includes a second plurality of stacked battery layers arranged in an inverted U-shaped geometry inside the second square battery can.

10. The prismatic battery pack of claim 9, wherein the second prismatic can is configured to have a thermal response time greater than 1300 seconds to reach a peak temperature less than 155°C after a thermal runaway (TR) event occurs in an adjacent first prismatic battery can.

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