Annealed pre-lithiated aluminum anode active material layer with high grain boundary distribution

Abstract

The invention relates to an annealed pre-lithiated aluminum anode active material layer with high grain boundary distribution. A method for manufacturing an anode electrode includes rolling a first aluminum foil layer; annealing the first aluminum foil layer to form a first annealed aluminum foil layer; mechanically bonding a first lithium metal foil layer between an anode current collector and the first annealed aluminum foil layer; and aging the anode electrode to pre-lithiate the first annealed aluminum foil layer.

Description

Technical Field

[0001] This disclosure relates to battery packs, and more particularly to the anodic active material layer of the anode electrode of a battery pack. Background Technology

[0002] The information provided in this section is intended to provide a general overview of the background of this disclosure. The work of the currently named inventors described in this section, and the aspects of the specification that may not have been otherwise identified as prior art at the time of filing, are 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 electric motors and a battery pack system comprising 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] The battery pack includes a cathode electrode, an anode electrode, and a separator. The cathode electrode includes a layer of cathode active material disposed on a cathode current collector. The anode electrode includes a layer of anode active material disposed on an anode current collector. Summary of the Invention

[0005] A method for manufacturing an anode electrode includes rolling a first aluminum foil layer; annealing the first aluminum foil layer to produce a first annealed aluminum foil layer; mechanically bonding a first lithium metal foil layer between an anode current collector and the first annealed aluminum foil layer; and aging the anode electrode to pre-lithiate the first annealed aluminum foil layer.

[0006] Among other features, the thickness of the first annealed aluminum foil layer is from 2 μm to 80 μm. The thickness of the first annealed aluminum foil layer is from 30 μm to 50 μm. The first annealed aluminum foil layer contains 94.0 to 99.99% by weight of aluminum. The annealing of the first annealed aluminum foil layer is performed at a temperature of 250°C to 550°C.

[0007] Among other features, the annealing period of the first annealed aluminum foil layer is from 10 minutes to 24 hours. The grain boundary distribution (>15°) of the first annealed aluminum foil layer after annealing is 46% to 80%. The pre-lithiation period is from 1 minute to 14 days.

[0008] Among other features, prior to the mechanical bonding, the method includes arranging a second lithium metal foil layer adjacent to the opposite side of the anode current collector and a second annealed aluminum foil layer adjacent to the second lithium metal foil layer. The mechanical bonding further includes mechanically bonding the first annealed aluminum foil layer, the first lithium metal foil layer, the anode current collector, the second lithium metal foil layer, and the second annealed aluminum foil layer. The aging further includes aging the anode electrode to pre-lithiate the second annealed aluminum foil layer.

[0009] A method for manufacturing an anode electrode includes rolling an aluminum foil layer; annealing the aluminum foil layer to form an annealed aluminum foil layer; mechanically bonding an insulating layer and the annealed aluminum foil layer to opposite sides of a lithium metal foil layer; and aging the anode electrode to pre-lithiate the annealed aluminum foil layer.

[0010] Among other features, the spacer layer includes a polymer layer. The thickness of the annealed aluminum foil layer is 2 μm to 80 μm. The thickness of the annealed aluminum foil layer is 30 μm to 50 μm. The annealed aluminum foil layer contains 94.0 to 99.99% by weight of aluminum. The annealing of the annealed aluminum foil layer is performed at a temperature of 250°C to 550°C.

[0011] Among other characteristics, the annealing period of the annealed aluminum foil layer is from 10 minutes to 24 hours. The grain boundary distribution (>15°) of the annealed aluminum foil layer is from 46% to 80%.

[0012] A method for manufacturing an anode electrode includes rolling an aluminum foil layer; annealing the aluminum foil layer to form an annealed aluminum foil layer; mechanically bonding a first lithium metal foil layer and a second lithium metal foil layer to opposite sides of the annealed aluminum foil layer; and aging the anode electrode to pre-lithiate the annealed aluminum foil layer.

[0013] Among other features, the annealing of the annealed aluminum foil layer is carried out at a temperature of 250°C to 550°C. The annealing period of the annealed aluminum foil layer is from 10 minutes to 24 hours.

[0014] Among other features, the annealed aluminum foil layer has a thickness of 2 μm to 80 μm, contains 94.0% to 99.99% by weight of aluminum, and has a grain boundary distribution (>15°) of 46% to 80%.

[0015] The present invention discloses the following solutions:

[0016] Option 1. A method for manufacturing an anode electrode, comprising:

[0017] Rolling the first aluminum foil layer;

[0018] The first aluminum foil layer is annealed to form a first annealed aluminum foil layer;

[0019] The first lithium metal foil layer is mechanically bonded between the anode current collector and the first annealed aluminum foil layer; and

[0020] The anode electrode is aged to pre-lithiate the first annealed aluminum foil layer.

[0021] Option 2. According to the method of Option 1, the thickness of the first annealed aluminum foil layer is 2 μm to 80 μm.

[0022] Option 3. According to the method of Option 1, the thickness of the first annealed aluminum foil layer is 30 μm to 50 μm.

[0023] Option 4. The method according to Option 1, wherein the first annealed aluminum foil layer comprises 94.0% to 99.99% by weight of aluminum.

[0024] Option 5. According to the method of Option 1, wherein the annealing of the first annealed aluminum foil layer is carried out at a temperature of 250°C to 550°C.

[0025] Option 6. The method according to Option 1, wherein the annealing period of the first annealed aluminum foil layer is from 10 minutes to 24 hours.

[0026] Option 7. The method according to Option 1, wherein the grain boundary distribution (>15°) of the first annealed aluminum foil layer after annealing is 46% to 80%.

[0027] Option 8. The method according to Option 1, wherein the pre-lithiation period is from 1 minute to 14 days.

[0028] Option 9. The method according to Option 1, further comprising:

[0029] Prior to the mechanical bonding, a second lithium metal foil layer adjacent to the opposite side of the anode current collector and a second annealed aluminum foil layer adjacent to the second lithium metal foil layer are arranged.

[0030] The mechanical bonding further includes mechanically bonding the first annealed aluminum foil layer, the first lithium metal foil layer, the anode current collector, the second lithium metal foil layer, and the second annealed aluminum foil layer.

[0031] The aging process further pre-lithiates the second annealed aluminum foil layer.

[0032] Option 10. A method for manufacturing an anode electrode, comprising:

[0033] Rolled aluminum foil layer;

[0034] The aluminum foil layer is annealed to form an annealed aluminum foil layer;

[0035] The separator layer and the annealed aluminum foil layer are mechanically bonded to opposite sides of the lithium metal foil layer; and

[0036] The anode electrode is aged to pre-lithiate the annealed aluminum foil layer.

[0037] Option 11. The method according to Option 10, wherein the spacer layer comprises a polymer layer.

[0038] Option 12. The method according to Option 10, wherein the thickness of the annealed aluminum foil layer is from 2 μm to 80 μm.

[0039] Option 13. The method according to Option 10, wherein the thickness of the annealed aluminum foil layer is 30 μm to 50 μm.

[0040] Option 14. The method according to Option 10, wherein the annealed aluminum foil layer comprises 94.0 to 99.99% by weight of aluminum.

[0041] Option 15. The method according to Option 10, wherein the annealing of the annealed aluminum foil layer is performed at a temperature of 250°C to 550°C.

[0042] Option 16. The method according to Option 10, wherein the annealing period of the annealed aluminum foil layer is from 10 minutes to 24 hours.

[0043] Option 17. The method according to Option 10, wherein the grain boundary distribution (>15°) of the annealed aluminum foil layer is 46% to 80%.

[0044] Option 18. A method for manufacturing an anode electrode, comprising:

[0045] Rolled aluminum foil layer;

[0046] The aluminum foil layer is annealed to form an annealed aluminum foil layer;

[0047] The first lithium metal foil layer and the second lithium metal foil layer are mechanically bonded to opposite sides of the annealed aluminum foil layer; and

[0048] The anode electrode is aged to pre-lithiate the annealed aluminum foil layer.

[0049] Option 19. The method according to Option 18, wherein:

[0050] The annealing of the annealed aluminum foil layer is carried out at a temperature of 250°C to 550°C, and

[0051] The annealing period for the annealed aluminum foil layer is from 10 minutes to 24 hours.

[0052] Option 20. The method according to Option 18, wherein:

[0053] The thickness of the annealed aluminum foil layer is from 2 μm to 80 μm.

[0054] The annealed aluminum foil layer contains 94.0% to 99.99% by weight of aluminum, and

[0055] The grain boundary distribution (>15°) of the annealed aluminum foil layer is 46% to 80%.

[0056] The further applicability of this disclosure will be apparent from the detailed description, claims, and drawings. The detailed description and specific embodiments are intended to be illustrative only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0057] This disclosure will be more fully understood from the detailed description and the accompanying drawings, in which:

[0058] Figure 1 This is a side cross-sectional view of an example of a battery pack according to the present disclosure.

[0059] Figure 2A and Figure 2B These are side cross-sectional views of an example of an anode electrode according to this disclosure before and after aging / pre-lithiation;

[0060] Figure 3 It is used to form Figure 2A and 2B Functional block diagram of an example of the rolling process for the anodic active material layer;

[0061] Figure 4A and Figure 4B These are side cross-sectional views of another example of the anode electrode according to this disclosure before and after aging / pre-lithiation;

[0062] Figure 5 It is used to form Figure 4A and 4B Functional block diagram of another example of the rolling process for the anodic active material layer;

[0063] Figure 6A and Figure 6B These are side cross-sectional views of another example of the anode electrode according to this disclosure before and after aging / pre-lithiation;

[0064] Figure 7 It is used to form Figure 6A and 6B Functional block diagram of another example of the rolling process for the anodic active material layer;

[0065] Figure 8 The molecular structures of aluminum foil and annealed pre-lithiated aluminum foil according to this disclosure are shown;

[0066] Figure 9A and9B Examples of grain boundary distribution (>15°) for aluminum foil and annealed aluminum foil are shown respectively;

[0067] Figure 10 An example of a lithium-ion diffusion path within a LiAl alloy according to this disclosure is shown;

[0068] Figure 11 Examples are energy dispersive spectral elemental diagrams of double-sided pre-lithiated aluminum foil and double-sided annealed pre-lithiated aluminum foil according to this disclosure; and

[0069] Figure 12 Examples of X-ray diffusion maps of aluminum foil, pre-lithiated aluminum foil, annealed aluminum foil, and annealed pre-lithiated aluminum foil are shown.

[0070] In the accompanying drawings, reference numerals may be used repeatedly to identify similar and / or identical elements. Detailed Implementation

[0071] Although the battery pack according to this disclosure is shown in the context of an electric vehicle, the battery pack can be used in stationary applications and / or other applications.

[0072] Aluminum has attracted attention as an anode active material for high-energy-density all-solid-state battery packs (ASSB). Aluminum is abundant and inexpensive, and possesses a suitable operating potential (~0.3V vs Li). + Aluminum has a theoretical capacity of 990 mAh / g (from Al (α phase, fcc) to LiAl (β phase, cubic)) and a volume change of 96%, which is lower than the 310% volume change of silicon anode electrodes. However, even after pre-lithiation, aluminum exhibits poor initial coulombic efficiency and capacity delivery, likely due to diffusion trapping and mechanical fracture of active lithium.

[0073] This disclosure relates to aluminum anode electrodes for use in battery packs, such as ASSB. According to this disclosure, aluminum foil is rolled and annealed to refine the aluminum grains and increase the sharpness of the grain boundaries (GBs). The annealed aluminum foil is then subjected to a pretreatment process (pre-lithiation). During pre-lithiation, the use of annealed aluminum foil effectively increases the GB distribution and promotes lithium-ion diffusion within the anode electrode. The pretreatment triggers a spontaneous transition from the α phase (aluminum structure) to the β phase (LiAl), which compensates for the loss of active lithium to enhance battery cycling.

[0074] Now for reference Figure 1The battery pack 10 includes C cathode electrodes 20, A anode electrodes 40, and S separators 32 arranged in a predetermined order within the battery pack stack 12, where C, S, and A are integers greater than zero. In some instances, the battery pack is an all-solid-state battery pack. The battery pack stack 12 is arranged within a housing 50. The C cathode electrodes 20-1, 20-2, ..., 20-C include a cathode active material layer 24 on one or both sides of the cathode current collector 26. The A anode electrodes 40-1, 40-2, ..., 40-A include an anode active material layer 42 and an anode current collector 46.

[0075] During charging / discharging, A anode electrodes 40 and C cathode electrodes 20 exchange lithium ions. In some instances, the cathode active material layer 24 includes a coating applied to the current collector, the coating comprising one or more active materials, one or more optional conductive additives, and / or one or more optional binder materials. In some instances, the S separators include a solid electrolyte or a separator layer such as a polymer layer.

[0076] In some instances, the cathode current collector 26 comprises metal foil, metal mesh, perforated metal, 3D metal foam, and / or expanded metal. In some instances, the current collector is made of one or more materials selected from stainless steel, aluminum, and / or alloys thereof. External tabs 28 and 48 are connected to the current collectors of the cathode and anode electrodes, respectively, and may be arranged on the same or different sides of the battery pack stack 12. External tabs 28 and 48 are connected to the terminals of the battery pack stack 12.

[0077] Now for reference Figures 2A to 3 An example of an anode electrode 120 according to the present disclosure during processing is shown. The anode electrode 120 includes aluminum foil layers 112 and 116, which are rolled (pressed and / or heated) multiple times using one or more sets of rolls and annealed before being mechanically bonded to lithium metal foil layers 114 and 115 and an anode current collector 117.

[0078] Aluminum foil layers 112 and 116 are rolled once or multiple times to ensure precise control over foil thickness and shape. In some examples, the rolled aluminum foil thickness is from 2 μm to 80 μm. In some examples, the rolled aluminum foil thickness is from 30 μm to 50 μm (e.g., 40 μm). In some examples, aluminum foil layers 112 and 116 contain 94.0 wt% to 99.99 wt% aluminum. In some examples, aluminum foil layers 112 and 116 contain 98.0 wt% to 99.95 wt% aluminum (e.g., 99 wt%).

[0079] After rolling, aluminum foil layers 112 and 116 are annealed. During annealing, recrystallization and polygonization begin to refine the grains and increase the sharpness of the grain boundaries. In some examples, annealing is performed at temperatures ranging from 250°C to 550°C. In some examples, annealing is performed at temperatures ranging from 300°C to 400°C (e.g., 350°C). In some examples, the annealing period is from 10 minutes to 24 hours. In some examples, the annealing period is from 30 minutes to 90 minutes (e.g., 60 minutes).

[0080] In some instances, the grain boundary distribution (>15°) after annealing is 46% to 80%. In some instances, the grain boundary distribution (>15°) after annealing is 60% to 70% (e.g., 65%).

[0081] After rolling and annealing, aluminum foil layers 112 and 116 are mechanically bonded to lithium metal foil layers 114 and 115 disposed on opposite sides of the anode current collector 117 (e.g., copper layer).

[0082] exist Figure 2B In the diagram, the anode electrode 120 is shown as anode electrode 120' after aging. Aluminum foil layers 112 and 116 and lithium metal foil layer 114 are aged for a predetermined period to allow pre-lithiation to occur. After aging, anode electrode 120' comprises bilayers 144 and 145, each layer comprising an outer aluminum layer and an inner lithium-aluminum layer.

[0083] exist Figure 3 In this process, rollers 150 and 152, comprising lithium metal foil layers 114 and 115, are supplied between a pair of rollers 154. Roller 153 supplies anode current collector 117 between the pair of rollers 154. Rollers 156 and 158 supply annealed aluminum foil layers 112 and 116 between the pair of rollers 154. The pair of rollers 154 mechanically bond the layers to form anode electrode 120, which is collected onto roller 172. Following the rolling process is an aging process to allow spontaneous pre-lithiation and formation of the lithium-aluminum layer 144.

[0084] In some examples, the thickness of the lithium metal foil layer 114 is from 2 μm to 50 μm. In some examples, the thickness of the lithium metal foil layer 114 is from 10 μm to 30 μm (e.g., 20 μm). In some examples, the pre-lithiation period is from 1 minute to 14 days. In some examples, the pre-lithiation period is from 6 hours to 10 hours (e.g., 8 hours).

[0085] Now for reference Figures 4A to 5 The anode electrode 220 is shown. Figure 4AThe image shows an anode electrode 220 before aging / pre-lithiation. The anode electrode 220 includes a mechanically bonded separator layer 212, a lithium metal foil layer 214, and an annealed aluminum foil layer 216. In some examples, the separator layer 212 includes a polymer layer. In some examples, the polymer layer includes a polyethylene terephthalate (PET) film, although other materials may also be used.

[0086] exist Figure 4B In this embodiment, the anode electrode 220 is shown as an anode electrode 220' after aging for a predetermined period to allow pre-lithiation to occur. After aging, the anode electrode 220' comprises a double layer 190, which includes an annealed aluminum layer-lithium aluminum (LiAl) layer arranged adjacent to the separator layer 212. In this example, the annealed aluminum foil layer may include terminals that serve as anode current collector connections.

[0087] exist Figure 5 In this process, a roller 150, including a lithium metal foil layer 214, is supplied between a pair of rollers 154. A roller 156 supplies an annealed aluminum foil layer 216 between the pair of rollers 154. A roller 260 supplies a spacer layer 212 between the pair of rollers 154. Pressure and / or heat are applied to the rollers 154 to mechanically bond the layers of the anode electrode 220, which is then collected onto a roller 172 and allowed to age to allow pre-lithiation as described above to occur.

[0088] Now for reference Figures 6A to 7 The anode electrode 320 is shown. Figure 8 The image shows an anode electrode 320 after pressing and before aging / pre-lithiation. The anode electrode 320 includes lithium metal foil layers 312 and 316 disposed on opposite sides of an annealed aluminum foil layer 314.

[0089] exist Figure 6B In the diagram, the anode electrode 320 is shown as an aged anode electrode 320'. The anode electrode 320' includes two double layers 342 and 346 (each double layer comprising lithium aluminum (LiAl)-annealed aluminum) on opposite sides of an annealed aluminum foil layer 314. In this example, the annealed aluminum foil layer may include terminals for use as anode current collector connections.

[0090] exist Figure 7 In this process, a roller 350, including an annealed aluminum foil layer 314, is supplied between a pair of rollers 154. Rollers 356 and 360 supply lithium metal foil layers 312 and 316 between the pair of rollers 154. The pair of rollers 154 apply pressure and / or heat to mechanically bond the layers of the anode electrode 320, which is collected on roller 172 and allowed to age to allow pre-lithiation to occur as described above.

[0091] Now for reference Figures 8 to 9BThe pre-lithiation step triggers a spontaneous transition from the α phase (Al structure, face-centered cubic, fcc) to the β phase (LiAl, cubic), in which the formed LiAl compensates for the loss of active lithium to enhance battery cycling. Figure 8 (Aluminum atoms 406, lithium atoms 408). In Figure 9A and 9B The image shows aluminum foil before annealing (at 420°C) and after annealing (at 410°C). It can be seen that annealing adjusts the grain boundary distribution.

[0092] Now for reference Figure 10 and 11 Grain boundary diffusion is the fastest diffusion pathway. When Al-Al GB transforms into LiAl-Al or LiAl-LiAl GB (intense GB sliding), the phase transition alters the grain boundary (GB) morphology. The free volume of GB increases in situ, thereby enhancing the diffusion capacity of Li along the GB to counteract future Li intrusion. Conversely, for Li atom diffusion at the LiAl / Al phase boundary (PB), the interface changes are minimal due to the vertical movement of PB and the relatively unchanged PB interface (maintaining relatively low diffusion capacity). Compared to other pathways (phase boundaries, dislocation nuclei, or lattice), GB diffusion is the fastest diffusion pathway. Annealing of Al foil significantly increases the GB distribution, which greatly promotes lithium-ion diffusion.

[0093] exist Figure 11 The diagram shows an anode active material layer 510 comprising double-sided pre-lithiated aluminum foil and an anode active material layer 520 comprising double-sided annealed pre-lithiated aluminum foil after the same pre-lithiation period (7 days). The anode active material layer 520 comprising double-sided annealed pre-lithiated aluminum foil produces more Li-Al, indicating faster lithium-ion diffusion.

[0094] Now for reference Figure 12 The X-ray diffraction patterns of the aluminum foil at position 610, the pre-lithiated aluminum foil at position 614, the annealed aluminum foil at position 618, and the annealed pre-lithiated aluminum foil at position 622 are shown. The peaks of the pre-lithiated and annealed aluminum foils are in excellent agreement with the standard data for LiAl crystals in the Inorganic Crystal Structure Database (ICSD).

[0095] 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.

[0096] Various terms are used to describe spatial and functional relationships between components (e.g., between 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 the first and second components in the foregoing disclosure, the relationship can be a direct relationship in which no other intermediary components exist between the first and second components, or an indirect relationship in which one or more intermediary components exist between the first and second components (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 of A, at least one of B, and at least one of C.”

Claims

1. A method for manufacturing an anode electrode, comprising: Rolling the first aluminum foil layer; The first aluminum foil layer is annealed to form a first annealed aluminum foil layer; The first lithium metal foil layer is mechanically bonded between the anode current collector and the first annealed aluminum foil layer; and The anode electrode is aged to pre-lithiate the first annealed aluminum foil layer.

2. The method according to claim 1, wherein the thickness of the first annealed aluminum foil layer is 2 μm to 80 μm.

3. The method according to claim 1, wherein the thickness of the first annealed aluminum foil layer is 30 μm to 50 μm.

4. The method of claim 1, wherein the first annealed aluminum foil layer comprises 94.0 to 99.99% by weight of aluminum.

5. The method according to claim 1, wherein the annealing of the first annealed aluminum foil layer is carried out at a temperature of 250°C to 550°C.

6. The method according to claim 1, wherein the annealing period of the first annealed aluminum foil layer is from 10 minutes to 24 hours.

7. The method according to claim 1, wherein the grain boundary distribution (>15°) of the first annealed aluminum foil layer after annealing is 46% to 80%.

8. The method of claim 1, wherein the pre-lithiation period is from 1 minute to 14 days.

9. The method of claim 1, further comprising: Prior to the mechanical bonding, a second lithium metal foil layer adjacent to the opposite side of the anode current collector and a second annealed aluminum foil layer adjacent to the second lithium metal foil layer are arranged. The mechanical bonding further includes mechanically bonding the first annealed aluminum foil layer, the first lithium metal foil layer, the anode current collector, the second lithium metal foil layer, and the second annealed aluminum foil layer. The aging process further pre-lithiates the second annealed aluminum foil layer.

10. A method for manufacturing an anode electrode, comprising: Rolled aluminum foil layer; The aluminum foil layer is annealed to form an annealed aluminum foil layer; The separator layer and the annealed aluminum foil layer are mechanically bonded to the opposite side of the lithium metal foil layer; and The anode electrode is aged to pre-lithiate the annealed aluminum foil layer.

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