Coated foil-free bipolar solid state battery cell

Abstract

A bipolar battery cell includes A anode / bipolar current collectors, the anode / bipolar current collectors including an aluminum foil layer. The first side of the aluminum foil layer includes a lithium-aluminum alloy sub-layer and the second side of the aluminum foil layer includes an unreacted aluminum sub-layer. The S diaphragms include a first side disposed adjacent to a first side of a respective one of the A anode / bipolar current collectors. C cathode active material layers include a first side disposed adjacent to a second side of a respective one of the A anode / bipolar current collectors and a second side disposed adjacent to a second side of a respective one of the S separators. A, C, and S are integers greater than 1.

Description

Technical Field

[0001] This disclosure relates to battery packs, and more particularly to coated foil-free bipolar solid-state battery packs. Background Technology

[0002] The information provided in this section is intended to give a general overview of the background of this disclosure. The work of the currently named inventors, to the extent described in this section, and in respect of the specification which at the time of filing might not have otherwise qualified as prior art, is not expressly or impliedly acknowledged as prior art to this disclosure.

[0003] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid electric vehicles, and / or fuel cell vehicles, include one or more motors and battery pack systems, wherein the battery pack system includes one or more battery cells, modules, and / or packs. A power control system is used to control the charging and / or discharging of the battery pack system during charging and / or driving.

[0004] A bipolar battery pack includes a cathode electrode, an anode electrode, and a separator. The cathode electrode includes a layer of cathode active material (including cathode active material) disposed on one side of a clad bipolar current collector, such as a clad foil. The anode electrode includes a layer of anode active material (including anode active material) disposed on the other side of the clad bipolar current collector. Summary of the Invention

[0005] A bipolar battery pack includes A anode / bipolar current collectors, each comprising an aluminum foil layer. A first side of the aluminum foil layer includes a lithium-aluminum alloy sublayer, and a second side of the aluminum foil layer includes an unreacted aluminum sublayer. S separators include a first side arranged adjacent to the first side of a corresponding anode / bipolar current collector. C cathode active material layers include a first side arranged adjacent to the second side of a corresponding anode / bipolar current collector and a second side arranged adjacent to the second side of a corresponding separator. A, C, and S are integers greater than 1.

[0006] In some instances, the aluminum foil layer has a grain boundary distribution greater than 15%. The aluminum foil layer has a grain boundary distribution in the range of 20% to 45%. The aluminum foil layer contains aluminum in the range of 80% to 99.9% by weight. The aluminum foil layer has a thickness in the range of 6 to 60 μm. A carbon layer is coated on the second side of the aluminum foil layer. The first side of the aluminum foil layer is anodized.

[0007] In other features, the S membranes comprise a solid electrolyte comprising a sulfide and a poly(ethylene oxide) (PEO) binder. The C cathode active material layers comprise a cathode active material and a polytetrafluoroethylene (PTFE) binder.

[0008] A bipolar battery pack includes a first cathode electrode comprising a cathode active material layer disposed on a cathode current collector. A first separator is disposed adjacent to the first cathode electrode. N cells disposed adjacent to the first separator include a first anode / bipolar current collector comprising an aluminum foil layer, wherein a first side of the aluminum foil layer comprises a lithium-aluminum alloy and a second side comprises unreacted aluminum; a cathode active material layer disposed adjacent to the first anode / bipolar current collector; and a second separator comprising the first side of the cathode active material layer disposed adjacent to it. The second anode / bipolar current collector is disposed adjacent to the last of the N cells. N is an integer greater than 0.

[0009] Among other features, the aluminum foil layer has a grain boundary distribution ranging from 15% to 45%. The aluminum foil layer contains aluminum ranging from 80% to 99.9% by weight. The aluminum foil layer has a thickness ranging from 6 to 60 μm. A carbon layer is coated on the second side of the aluminum foil layer. The first side of the aluminum foil layer is anodized.

[0010] Among other features, the first diaphragm comprises a solid electrolyte, which includes a sulfide and a poly(ethylene oxide) (PEO) binder, and the cathode active material layer comprises a cathode active material and a polytetrafluoroethylene (PTFE) binder.

[0011] A bipolar battery pack includes a first cathode electrode comprising a cathode active material layer disposed on a cathode current collector. N cells arranged adjacent to the first cathode electrode include a first separator disposed adjacent to the first cathode electrode; a first anode / bipolar current collector comprising an aluminum foil layer, wherein a first side of the aluminum foil layer is disposed adjacent to the first separator and comprises a lithium-aluminum alloy, and a second side comprises unreacted aluminum; and a cathode active material layer disposed adjacent to the second side of the first anode / bipolar current collector. A second separator includes a first side disposed adjacent to the cathode active material layer. A second anode / bipolar current collector is disposed adjacent to the second separator. N is an integer greater than 0.

[0012] Among other features, the aluminum foil layer has a grain boundary distribution in the range of 15% to 45%, the aluminum foil layer contains aluminum in the range of 80% to 99.9% by weight, and the aluminum foil layer has a thickness in the range of 6 to 60 μm.

[0013] In other features, the second side of the aluminum foil layer is coated with a carbon layer. The first side of the aluminum foil layer is anodized. The S diaphragms contain a solid electrolyte comprising a sulfide and a poly(ethylene oxide) (PEO) binder, and the C cathode active material layers comprise a cathode active material and a polytetrafluoroethylene (PTFE) binder.

[0014] The further applicability of this disclosure will be apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended to be illustrative only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0015] This disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

[0016] Figure 1 It is a side cross-section of an example of a bipolar battery pack including a coated bipolar current collector;

[0017] Figure 2A and 2B This is a side cross-section of an example of a cathode and anode electrode;

[0018] Figure 3A This is a side cross-section of an example of a bipolar battery pack including a combined anode / bipolar current collector according to the present disclosure;

[0019] Figure 3B This is a side cross-section of an example of a combined anode / bipolar current collector according to this disclosure;

[0020] Figure 3C This is a side cross-section of an example of a combined anode / bipolar current collector according to this disclosure;

[0021] Figure 4 and 5 This is a side cross-section of an example of a bipolar battery pack including repeating cells according to the present disclosure;

[0022] Figure 6A and 6B This is a side cross-section of an example of a combined anode / bipolar current collector including a carbon layer according to the present disclosure;

[0023] Figure 7 This is a side cross-section of an example of a combined anode / bipolar current collector including an anodized surface according to the present disclosure;

[0024] Figure 8 This is a side cross-section of an example of a bipolar battery pack including repeating cells according to the present disclosure;

[0025] Figure 9 and 10 It is a graph illustrating the performance of the bipolar battery pack according to this disclosure.

[0026] In the accompanying drawings, reference numerals may be reused to designate similar and / or identical elements. Detailed Implementation

[0027] Although the battery pack shown in the context of an electric vehicle is described, the battery pack can be used in stationary applications and / or other applications.

[0028] A bipolar battery pack includes a cathode electrode and an anode electrode, which have surfaces separated by a separator. A coated current collector separates the other surfaces of the cathode and anode electrodes. Figures 1 to 2B This illustrates an exemplary bipolar battery pack including a coated current collector. Figures 3A to 10 This invention includes a combined anode and current collector that replace the cladding current collector according to the present disclosure. Due to the low-cost anode and low-cost bipolar current collector, this bipolar battery pack is cost-effective. The battery pack structure is simplified and easy to manufacture.

[0029] Now for reference Figure 1 The image shows a bipolar battery pack 10, such as a solid-state battery pack. The bipolar battery pack 10 includes C cathode electrodes 20-1, ..., and 20-C, A anode electrodes 40-1, ..., and 40-A, and S separators 32-1, ..., and 32-S. The cathode and anode electrodes are arranged in an alternating bipolar sequence within the battery pack stack 12, where C, S, and A are integers greater than 0. The battery pack stack 12 is housed within a casing 50.

[0030] The C cathode electrodes 20-1, 20-2, ..., 20-C include a cathode active material layer 24 disposed on a first side of the bipolar current collector 26. The A anode electrodes 40-1, 40-2, ..., 40-A include an anode active material layer 42 disposed on a second side of the bipolar current collector 26. The S diaphragms 32-1, 32-2, ..., 32-S are disposed between the C cathode electrodes 20 and the A anode electrodes 40 on the other sides.

[0031] In some instances, the A anode electrodes 40 and the C cathode electrodes 20 exchange lithium ions during charging / discharging. In some instances, the cathode active material layer 24 includes a coating comprising one or more active materials, one or more conductive additives, and / or one or more binder materials.

[0032] In some bipolar battery packs, the bipolar current collector 26 comprises first and second metal foil layers, such as copper and aluminum, which are mechanically bonded together to form a coated bipolar current collector. External tabs 28 and 48 are connected to electrodes at opposite ends of the bipolar battery pack cell 10. External tabs 28 and 48 are connected to the terminals of the battery pack cell.

[0033] Now for reference Figure 2A and 2B Examples of cathode and anode electrodes are shown. Figure 2A The image shows one of the C cathode electrodes 20 in more detail. The cathode active material layer 24 includes cathode active material 62, conductive additive 64, and adhesive 66 disposed on one side (e.g., the aluminum foil side) of the coated bipolar current collector 26.

[0034] exist Figure 2B The image shows one of the A anode electrodes 40 in more detail. The anode active material layer 42 includes an anode active material 72 disposed on the other side (e.g., the copper foil side) of the coated bipolar current collector 26, an optional conductive additive 74, and an optional binder 76.

[0035] Coated bipolar current collectors 26 are typically manufactured using a physical roll bonding method. Bonding of the foil layers (e.g., aluminum and copper) only occurs when the surface is clean and compressed under sufficiently high pressure between a pair of rollers to deform the metal foil. It is difficult to manufacture thin-thick coated bipolar current collectors 26. Typically, coated bipolar current collectors 26 have a thickness ranging from 35 μm to 500 μm. Annealing can be performed during the coating process to mechanically bond the coating layer, which increases manufacturing time and cost. Coated bipolar current collectors 26 are also prone to delamination, especially during the bending of the coating foil.

[0036] The bipolar current collector according to this disclosure includes an aluminum foil layer configured to act as both an anode active material to receive lithium ions and a bipolar current collector to conduct electrons between adjacent battery cells. In some examples, the aluminum foil layer has a grain boundary distribution of greater than 15%. In some examples, the aluminum foil layer has a grain boundary distribution in the range of 20% to 45% (e.g., 35%).

[0037] During the charging process of the bipolar battery pack, the aluminum foil layer is lithium-lithiated along a direction perpendicular to the electrode / electrolyte interface to form a dense Li-Al alloy layer. The thickness of this Li-Al layer can be controlled according to the cathode load. The unreacted aluminum foil acts as current leads to transfer electrons between the bipolar battery cells.

[0038] Now for reference Figure 3A This image shows a bipolar battery pack 100 according to the present disclosure. The bipolar battery pack 100 includes a cathode active material layer 120 (one disposed on a cathode current collector 110), a separator 132, and an anode / bipolar current collector 140. In this example, some of the cathode active material layers 120 are disposed between one side of the anode / bipolar current collector 140 and one side of the separator 132. The other side of the separator 132 is disposed adjacent to the other side of the anode of the anode / bipolar current collector 140.

[0039] Now for reference Figure 3B and3C The images show aluminum foil layers 200 and 200' before lithiation and after in-situ lithiation during battery charging, respectively. Figure 3B In this process, aluminum foil layer 200 is in-situ lithium-ionized along a direction perpendicular to the electrode / electrolyte interface. Also, as... Figure 3C As can be seen, a Li-Al alloy layer 220 is formed on one side of the aluminum foil layer 200', and an unreacted aluminum foil layer 224 is located on the other side of the aluminum foil layer 200'.

[0040] It can be recognized that bipolar battery packs can be manufactured using repeating cells with varying numbers of electrodes and separators. Figure 4 In this bipolar battery pack 300, a cathode current collector 310, a cathode active material layer 320, and a separator 332 are included. Each of the N cells 312 (where N is an integer greater than 0) includes an anode / bipolar current collector 340, a cathode active material layer 320, and a separator 332. Another anode / bipolar current collector 340 is arranged on the other side of the N cells 312.

[0041] exist Figure 5 In this bipolar battery pack 400, a cathode current collector 410 and a cathode active material layer 420 are included. Each of the N cells 412 (where N is an integer greater than 0) includes a separator 432, an anode / bipolar current collector 440, and a cathode active material layer 420. The separator 432 and the anode / bipolar current collector 440 are arranged on the other side of the N cells 412.

[0042] Now for reference Figure 6A This illustrates another method for manufacturing an anode / bipolar current collector. Aluminum foil layers 450 and 450' are shown before and after lithiation pretreatment, respectively. Aluminum foil layer 450 is lithiated on one side. For example, the aluminum foil can be pretreated using lithium foil. The lithium foil and aluminum foil react to form a Li-Al alloy. The first sublayer of the aluminum foil facing the lithium foil is converted into the Li-Al alloy. The second sublayer of the aluminum foil is not in contact with the lithium foil and does not react. After lithiation pretreatment, aluminum foil layer 450' acts as an anode / bipolar current collector. Aluminum foil layer 450' includes a Li-Al alloy layer 220 on one side and an unreacted aluminum foil layer 224 on the other side.

[0043] In some examples, the aluminum foil layer comprises 80 to 99.9 wt% Al. In some examples, the aluminum foil layer comprises 95 to 99.9 wt% Al (e.g., 98.6 wt%). In some examples, the thickness of the aluminum foil is in the range of 6 to 60 μm. In some examples, the thickness of the aluminum foil is in the range of 30 to 50 μm (e.g., 40 μm). In some examples, the aluminum foil layer has a grain boundary distribution greater than 15%. In some examples, the aluminum foil layer has a grain boundary distribution in the range of 20 to 45% (e.g., 35%).

[0044] Examples of aluminum foil layers with high grain boundary distribution can be found in commonly assigned U.S. Patent Applications Nos. 18 / 760,281 and 18 / 760,389 (corresponding to GM Docket Nos. P107816 and P107895), which are incorporated herein by reference in their entirety. In some examples, the aluminum foil layer is rolled and annealed to improve the grain boundary distribution. In some examples, the aluminum foil layer further includes iron (Fe) to improve the grain boundary distribution.

[0045] Now for reference Figure 6B This illustrates another method for manufacturing an anode / bipolar current collector. Aluminum foil layers 470 and 470' are shown before and after lithiation pretreatment, respectively. A conductive carbon layer 472 is coated onto the aluminum foil layer 470, followed by pretreatment. The conductive carbon layer 472 suppresses potential short circuits and acts as an electron conduction network for the cathode and anode electrodes. The aluminum foil layer 470' is lithiated on one side and includes a Li-Al alloy layer 220 on one side and an unreacted aluminum foil layer 224 on the other side.

[0046] Now for reference Figure 7 This illustrates another method for manufacturing the anode / bipolar current collector 500. Aluminum foil layers 508 and 508' are shown before and after lithiation pretreatment, respectively. Aluminum foil layer 508 is anodized on one side to create an anodized layer 510 (e.g., aluminum oxide), and then pretreated. Anodized layer 510' and a portion of aluminum foil layer 508' are lithiated to form a lithium aluminum oxide alloy (Li-AlO2) and a lithium alloy (Li-Al), respectively. Anodized layer 510' increases interfacial contact. Unreacted aluminum foil layer 524 is located on the other side.

[0047] exist Figure 8 In this bipolar battery pack 600, a cathode current collector 610 and a cathode active material layer 620 are included. Each of the N cells 612 (where N is an integer greater than 0) includes a separator 632, an anode / bipolar current collector 500, and a cathode active material layer 620. The separator 632 and the anode / bipolar current collector 500 are arranged on the other side of the N cells 612.

[0048] Now for reference Figure 9 and 10 This demonstrates the performance of the bipolar solid-state battery pack. Figure 9 The text displays the capacity versus the number of loops. Figure 10 The image shows voltage vs. capacity. In this example, the cathode electrode comprises 3 mAh / cm³. 2NMC721. The anode comprises a 40 μm Al / Fe foil lithium-lithiated with 10 wt% Li. The separator comprises a sulfide electrolyte. The cathode active material layer comprises polytetrafluoroethylene (PTFE) as a binder, and the separator comprises poly(ethylene oxide) (PEO) as a binder. It can be seen that this bipolar solid-state battery pack delivers most of the cathode capacity and performs well at 0.333C.

[0049] The foregoing description is merely exemplary and is in no way intended to limit this disclosure, its application, or its use. The broad teachings of this disclosure can be implemented in various forms. Therefore, although this disclosure includes specific examples, its true scope should not be limited thereto, as other modifications will become apparent upon examination of the drawings, specification, and the following claims. It should be understood that one or more steps within the method may be performed in a different order (or simultaneously) without altering the principles of this disclosure. Furthermore, although the embodiments are described above as having certain features, any one or more features described with respect to any embodiment of this disclosure may be implemented in any other embodiment and / or combined with features of any other embodiment, even if such combination is not explicitly described. In other words, the embodiments are not mutually exclusive, and substitution of one or more embodiments for each other remains within the scope of this disclosure.

[0050] Various terms are used to describe spatial and functional relationships between elements (e.g., modules, circuit elements, semiconductor layers, etc.), including “connection,” “joint,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as “direct,” when describing the relationship between a first element and a second element in the foregoing disclosure, the relationship can be a direct relationship in which no other intermediate elements exist between the first element and the second element, or an indirect relationship in which one or more intermediate elements exist between the first element and the second element (spatially or functionally). The phrase “at least one of A, B, and C” as used herein should be interpreted as referring to the logic of OR (A or B or C) using non-exclusive logic, and should not be interpreted as referring to “at least one A, at least one B, and at least one C.”

[0051] This application may also include the following technical solutions:

[0052] Option 1. A bipolar battery pack, comprising:

[0053] A single anode / bipolar current collector, comprising an aluminum foil layer.

[0054] The first side of the aluminum foil layer includes a lithium-aluminum alloy sublayer, and the second side of the aluminum foil layer includes an unreacted aluminum sublayer;

[0055] S diaphragms, each including a first side arranged adjacent to a first side of a corresponding one of the A anode / bipolar current collectors; and

[0056] C cathode active material layers, each comprising a first side arranged adjacent to the second side of a corresponding one of the A anode / bipolar current collectors and a second side arranged adjacent to the second side of a corresponding one of the S diaphragms.

[0057] Where A, C, and S are integers greater than 1.

[0058] Option 2. The bipolar battery pack according to Option 1, wherein the aluminum foil layer has a grain boundary distribution of more than 15%.

[0059] Option 3. The bipolar battery pack according to Option 2, wherein the aluminum foil layer has a grain boundary distribution in the range of 20% to 45%.

[0060] Option 4. The bipolar battery pack according to Option 1, wherein the aluminum foil layer contains aluminum in the range of 80% to 99.9% by weight.

[0061] Option 5. The bipolar battery pack according to Option 1, wherein the aluminum foil layer has a thickness in the range of 6 to 60 μm.

[0062] Option 6. The bipolar battery pack according to Option 1, wherein the second side of the aluminum foil layer is coated with a carbon layer.

[0063] Option 7. The bipolar battery pack according to Option 1, wherein the first side of the aluminum foil layer is anodized.

[0064] Option 8. The bipolar battery pack according to Option 1, wherein:

[0065] The S membranes contain a solid electrolyte comprising a sulfide and a poly(ethylene oxide) (PEO) binder, and

[0066] The C cathode active material layers include cathode active material and polytetrafluoroethylene (PTFE) adhesive.

[0067] Option 9. A bipolar battery pack, comprising:

[0068] The first cathode electrode includes a cathode active material layer disposed on the cathode current collector;

[0069] A first diaphragm is arranged adjacent to the first cathode electrode;

[0070] The N units arranged adjacent to the first diaphragm include:

[0071] A first anode / bipolar current collector comprising an aluminum foil layer, wherein a first side of the aluminum foil layer comprises a lithium-aluminum alloy and a second side comprises unreacted aluminum;

[0072] The cathode active material layer adjacent to the first anode / bipolar current collector arrangement; and

[0073] The second diaphragm includes a first side disposed adjacent to the cathode active material layer; and

[0074] The second anode / bipolar current collector is arranged adjacent to the last of the N units.

[0075] Where N is an integer greater than 0.

[0076] Option 10. The bipolar battery pack according to Option 9, wherein the aluminum foil layer has a grain boundary distribution in the range of 15% to 45%.

[0077] Option 11. The bipolar battery pack according to Option 9, wherein the aluminum foil layer contains aluminum in the range of 80% to 99.9% by weight.

[0078] Option 12. The bipolar battery pack according to Option 9, wherein the aluminum foil layer has a thickness in the range of 6 to 60 μm.

[0079] Option 13. The bipolar battery pack according to Option 9, wherein the second side of the aluminum foil layer is coated with a carbon layer.

[0080] Option 14. The bipolar battery pack according to Option 9, wherein the first side of the aluminum foil layer is anodized.

[0081] Option 15. The bipolar battery pack according to Option 9, wherein:

[0082] The first diaphragm contains a solid electrolyte, which includes a sulfide and a poly(ethylene oxide) (PEO) binder, and

[0083] The cathode active material layer includes a cathode active material and a polytetrafluoroethylene (PTFE) adhesive.

[0084] Option 16. A bipolar battery pack, comprising:

[0085] The first cathode electrode includes a cathode active material layer disposed on the cathode current collector;

[0086] The N units arranged adjacent to the first cathode electrode include:

[0087] A first diaphragm is arranged adjacent to the first cathode electrode;

[0088] A first anode / bipolar current collector comprising an aluminum foil layer, wherein a first side of the aluminum foil layer is disposed adjacent to a first diaphragm and comprises a lithium-aluminum alloy, and a second side comprises unreacted aluminum; and

[0089] A cathode active material layer is arranged on the second side adjacent to the first anode / bipolar current collector;

[0090] The second diaphragm includes a first side arranged adjacent to the last of the N units, containing a layer of cathode active material; and

[0091] The second anode / bipolar current collector is arranged adjacent to the second diaphragm.

[0092] Where N is an integer greater than 0.

[0093] Option 17. The bipolar battery pack according to Option 16, wherein:

[0094] The aluminum foil layer has a grain boundary distribution in the range of 15% to 45%.

[0095] The aluminum foil layer contains aluminum in the range of 80% to 99.9% by weight, and

[0096] The aluminum foil layer has a thickness in the range of 6 to 60 μm.

[0097] Option 18. The bipolar battery pack according to Option 16, wherein the second side of the aluminum foil layer is coated with a carbon layer.

[0098] Option 19. The bipolar battery pack according to Option 16, wherein the first side of the aluminum foil layer is anodized.

[0099] Option 20. The bipolar battery pack according to Option 16, wherein:

[0100] The S membranes contain a solid electrolyte comprising a sulfide and a poly(ethylene oxide) (PEO) binder, and

[0101] The C cathode active material layers include cathode active material and polytetrafluoroethylene (PTFE) adhesive.

Claims

1. A bipolar battery pack, comprising: A single anode / bipolar current collector, comprising an aluminum foil layer. The first side of the aluminum foil layer includes a lithium-aluminum alloy sublayer, and the second side of the aluminum foil layer includes an unreacted aluminum sublayer; S diaphragms, each including a first side arranged adjacent to a first side of a corresponding one of the A anode / bipolar current collectors; and C cathode active material layers, each comprising a first side arranged adjacent to the second side of a corresponding one of the A anode / bipolar current collectors and a second side arranged adjacent to the second side of a corresponding one of the S diaphragms. Where A, C, and S are integers greater than 1.

2. The bipolar battery pack according to claim 1, wherein the aluminum foil layer has a grain boundary distribution of more than 15%.

3. The bipolar battery pack according to claim 2, wherein the aluminum foil layer has a grain boundary distribution in the range of 20% to 45%.

4. The bipolar battery pack according to claim 1, wherein the aluminum foil layer contains aluminum in the range of 80% to 99.9% by weight.

5. The bipolar battery pack according to claim 1, wherein the aluminum foil layer has a thickness in the range of 6 to 60 μm.

6. The bipolar battery pack according to claim 1, wherein the second side of the aluminum foil layer is coated with a carbon layer.

7. The bipolar battery pack according to claim 1, wherein the first side of the aluminum foil layer is anodized.

8. The bipolar battery pack according to claim 1, wherein: The S membranes contain a solid electrolyte comprising a sulfide and a poly(ethylene oxide) (PEO) binder, and The C cathode active material layers include cathode active material and polytetrafluoroethylene (PTFE) adhesive.

9. A bipolar battery pack, comprising: The first cathode electrode includes a cathode active material layer disposed on the cathode current collector; A first diaphragm is arranged adjacent to the first cathode electrode; The N units arranged adjacent to the first diaphragm include: A first anode / bipolar current collector comprising an aluminum foil layer, wherein a first side of the aluminum foil layer comprises a lithium-aluminum alloy and a second side comprises unreacted aluminum; A cathode active material layer adjacent to the first anode / bipolar current collector arrangement; and The second diaphragm includes a first side disposed adjacent to the cathode active material layer; and The second anode / bipolar current collector is arranged adjacent to the last of the N units. Where N is an integer greater than 0.

10. The bipolar battery pack according to claim 9, wherein the aluminum foil layer has a grain boundary distribution in the range of 15% to 45%.

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