HIGH-PERFORMANCE SOLID-STATE BATTERY CELL WITH SULFIDE SOLID ELECTROLYTE AND SILICON ANODE ELECTRODE

Abstract

A solid-state battery cell comprises A anode electrodes, each comprising an anode active material layer disposed on an anode current collector. The anode current collector has a roughened outer surface, the anode active material layer comprises silicon, and the outer surface of the anode active material layer has a plurality of convex spherical shapes. C cathode electrodes each comprise a cathode active material layer disposed on a cathode current collector. The cathode active material layer comprises cathode active material and a sulfide solid electrolyte. The cathode active material is selected from a group consisting of LiNixMnyCo1-xy-yO2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), LiNxAlyCo1-xy-yO2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), and LiNixMnyAlzCo1-xy-zO2 (where 0.95 > x ≥ 0.33; y ≥ 0.01; and Z ≥ 0.01). Separators comprise a sulfide membrane, where A, C, and S are integers greater than one.

Description

INTRODUCTION

[0001] The information contained in this section is intended to provide a general context for the disclosure. Work by the presently named inventors, to the extent described in this introduction, as well as aspects of the description that might not otherwise be considered prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against this disclosure.

[0002] The present disclosure relates to battery cells and, more particularly, to high performance solid state battery cells.

[0003] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, comprise one or more electric motors and a battery system with 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 system during charging and / or driving.

[0004] Battery cells comprise cathode electrodes, anode electrodes, and separators. The cathode electrodes comprise a cathode active material layer disposed on a cathode current collector. The anode electrodes comprise an anode active material layer disposed on an anode current collector. SUMMARY OF THE INVENTION

[0005] A solid-state battery cell comprises A anode electrodes, each having an anode active material layer arranged on an anode current collector. The anode current collector has a roughened outer surface, the anode active material layer comprises silicon, and the outer surface of the anode active material layer has a plurality of convex spherical shapes. C cathode electrodes each comprise a cathode active material layer arranged on a cathode current collector. The cathode active material layer comprises cathode active material and a sulfide solid electrolyte. The cathode active material is selected from a group consisting of LiNi x Mn y Co 1-x-y O2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), LiN x Al y Co 1-x-y O2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), and LiNi x Mn y Al z Co 1-x-y-zO2 (where 0.95 > x ≥ 0.33; y ≥ 0.01; and Z ≥ 0.01). S separators comprise a sulfide membrane, where A, C, and S are integers greater than one.

[0006] In other features, the anode current collector is made of a material selected from a group consisting of copper, stainless steel, nickel, iron, titanium, tin, and their alloys. The anode current collector has a thickness in the range of 10 µm to 20 µm. The roughened outer surface has a roughness in the range of 0.1 µm to 12 µm.

[0007] In other features, a D50 particle size of the second cathode active material ranges from 2 µm to 10 µm. The cathode active material comprises an outer coating layer of lithium niobate (LiNbO3). The outer coating layer comprises 0.5 wt% to 5 wt% of the cathode active material coated with the outer coating layer. The sulfide solid electrolyte comprises Li6PS5Cl.

[0008] In other features, the cathode active material layer comprises cathode active material in the range of 40 wt% to 90 wt%, sulfide solid electrolytes in the range of 10 wt% to 50 wt%, a conductive additive in the range of 0.1 wt% to 10 wt%, and a binder in the range of 0.1 wt% to 3 wt%. The maximum thickness of the anode active material layer is in the range of 5 µm to 20 µm.

[0009] In other features, the peak-to-valley distance of the plurality of convex spherical surfaces ranges from 0.1 µm to 5 µm. The sulfide membrane consists of a sulfide solid electrolyte and a binder. The sulfide solid electrolyte comprises Li6PS5Cl, and the binder comprises poly(ethylene oxide) (PEO). The S separators comprise sulfide solid electrolytes in the range of 85 to 99 wt%, binders in the range of 1 to 10 wt%, and a filler in the range of 0.1 to 1 wt%.

[0010] In other features, the S separators comprise a lithium salt in the range of 0.1 wt% to 5 wt% of the sulfide membrane, wherein the lithium salt is selected from a group consisting of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), and combinations thereof.

[0011] In other features, the filler is selected from a group consisting of an oxide-based sulfide solid electrolyte and a ceramic oxide.

[0012] A solid-state battery cell comprises A anode electrodes, each having an anode active material layer arranged on an anode current collector. The anode current collector has a roughened outer surface, the anode active material layer comprises silicon, and the outer surface of the anode active material layer has a plurality of convex spherical shapes. C cathode electrodes each comprise a cathode active material layer arranged on a cathode current collector. The cathode active material layer comprises cathode active material and a sulfide solid electrolyte comprising Li6PS5Cl. The cathode active material is selected from a group consisting of LiNi x Mn y Co 1-x-y O2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), LiN x Al y Co 1-x-y O2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), and LiNi x Mn y Al z Co 1-x-y-zO2 (where 0.95 > x ≥ 0.33; y ≥ 0.01; and Z ≥ 0.01). The cathode active material comprises an outer coating layer of lithium niobate (LiNbO3). Separators comprise a sulfide membrane containing Li6PS5Cl and a binder containing poly(ethylene oxide) (PEO), where A, C, and S are integers greater than one.

[0013] In other features, the anode current collector is made of a material selected from a group consisting of copper, stainless steel, nickel, iron, titanium, tin, and their alloys. The anode current collector has a thickness in the range of 10 µm to 20 µm. The roughened outer surface has a roughness in the range of 0.1 µm to 12 µm.

[0014] In other features, the peak-to-valley distance of the plurality of convex spherical surfaces ranges from 0.1 µm to 5 µm. The S separators comprise sulfide solid electrolytes in the range of 85 to 99 wt%, a binder in the range of 1 to 10 wt%, and a filler in the range of 0.1 to 1 wt%.

[0015] In other features, the S separators comprise a lithium salt in the range of 0.1 wt% to 5 wt% of the sulfide membrane. The filler is selected from a group consisting of an oxide-based sulfide solid electrolyte and a ceramic oxide.

[0016] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present disclosure will be better understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a side cross-sectional view of an exemplary solid-state battery cell having cathode electrodes, anode electrodes, and separators according to the present disclosure; Fig. 2A is a side cross-sectional view of an exemplary cathode electrode according to the present disclosure; Fig. 2B is a side cross-sectional view of an exemplary cathode active material particle having an outer coating layer according to the present disclosure; Fig. 3 is a side cross-sectional view of an exemplary anode electrode according to the present disclosure; Fig. 4 is a side cross-sectional view of an exemplary anode electrode, cathode electrode, and separator of a solid-state battery cell according to the present disclosure; Fig. 5 and Fig. 6 are graphs showing capacity versus cycles and voltage versus capacity, respectively, at different discharge rates of an exemplary solid-state battery according to the present disclosure; Fig. 7 is a graph showing voltage versus capacity at different charging rates of an exemplary solid-state battery according to the present disclosure; Fig. 8 is a graph showing voltage versus capacity in the 3C charge / discharge cycling of an exemplary solid-state battery according to the present disclosure; and Fig. 9 is a graph showing capacity and Coulombic efficiency as a function of cycles in the 3C charge / discharge cycling of an exemplary solid-state battery according to the present disclosure.

[0018] Reference symbols may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0019] Although battery cells according to the present disclosure are shown in the context of electric vehicles, the solid-state battery cells may also be used in stationary applications and / or other applications.

[0020] Solid-state battery cells offer greater safety and a wide operating temperature range. However, the safe integration of electrode active material to enable high performance while maintaining long-term cycling is a technical challenge. Solid-state battery cells conduct lithium ions less efficiently at the micro level between the active material and the solid electrolyte particles, and lithium ions less efficiently at the macro level between the electrode layer and the solid electrolyte layer.

[0021] An advanced solid-state battery according to the present disclosure with good cell performance and cyclability comprises a dry-film cathode electrode, a separator with a sulfide solid electrolyte membrane with high ionic conductivity, and a silicon anode electrode. The silicon anode electrode comprises a plurality of convex, spherical surfaces formed by depositing silicon on a roughened anode current collector using physical vapor deposition (PVD).

[0022] The solid-state battery cell forms favorable lithium-ion conduction at the particle and layer interfaces. The convex spherical surfaces of the silicon anode electrode reduce the stress generated during cycling and allow the lithiated silicon to expand, improving the cell's cyclability. The solid-state battery cell offers good discharge rates and fast charging capabilities. The solid-state battery cell enables stable cycling of the battery cell for more than 600 cycles.

[0023] In some examples, the cathode electrodes are manufactured using a dry roll-to-roll process. In some examples, a cathode active material layer comprises cathode active material, a sulfide solid electrolyte, and a fibrillating binder (e.g., polytetrafluoroethylene (PTFE)). The dry manufacturing process eliminates the use of solvents and prevents their influence on the lithium-ion conduction of the sulfide solid electrolyte. The dry process also eliminates the need for drying equipment to remove the solvent from the cathode active material layer after casting.

[0024] In some examples, the separators comprise a membrane with a sulfide solid electrolyte and a binder (e.g., poly(ethylene oxide) (PEO)). In some examples, the separators are fabricated using a wet process to enable a low thickness. The separators can be cast onto the cathode or anode electrode or fabricated as a freestanding membrane on a removable substrate. In some examples, the PEO binder is pretreated with LiTFSI and Si2O particles to reduce the crystallinity of the polymer binder and improve ionic conductivity.

[0025] In some examples, the anode electrodes comprise silicon active material with a plurality of convex spherical surfaces deposited on a roughened anode current collector. The plurality of convex spherical surfaces allows for a larger surface area that can interact with the sulfide solid electrolyte of the separator membrane to increase lithium ion conduction pathways and enhance the performance of the solid-state battery cell. The plurality of convex spherical surfaces also contributes to stress relief during cycling by allowing expansion of the lithiated silicon.

[0026] With reference to Fig. 1, a solid-state battery cell 10 comprises C cathode electrodes 20, A anode electrodes 40, and S separators 32 arranged in a predetermined order in a battery cell stack 12, where C, A, and S are integers greater than one. The battery cell stack 12 is housed in a casing 50. The C cathode electrodes 20-1, 20-2, ..., and 20-C include cathode active material layers 24 arranged on one or both sides of a cathode current collector 26.

[0027] The anode electrodes 40-1, 40-2, ..., and 40-A include anode active material layers 42 disposed on one or both sides of the anode current collectors 46. During charging / discharging, the A-anode electrodes 40 and the C-cathode electrodes 20 exchange lithium ions. In some examples, the cathode active material layers 24 are formed using a dry process. A mixture of one or more cathode active materials, a sulfide solid electrolyte, and / or one or more binders is mixed / sheared to form fibrils, transferred to the cathode current collectors, and calendered.

[0028] In some examples, the cathode current collector 26 and / or the anode current collector 46 comprise a metal foil, a metal mesh, perforated metal, three-dimensional (3D) metal foam, and / or expanded metal. The outer tabs 28 and 48 are connected to the current collectors of the cathode and anode electrodes, respectively, and can be arranged on the same or different sides of the battery cell stack 12. The outer tabs 28 and 48 are connected to terminals of the solid-state battery cells.

[0029] With reference to Fig. 2A and Fig. 2B shows one of the C cathode electrodes 20 in more detail. In Fig. 2A, the cathode active material layer 24 of the C cathode electrodes 20 comprises cathode active material 62, the sulfide solid electrolyte 64, and a fibrillating binder 66, which are mixed / sheared to form fibrils and transferred to the cathode current collector in a dry roll-to-roll process.

[0030] In some examples, the cathode active material comprises LiNi x Mn y Co 1-x-y O2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05). In some examples, a D50 particle size of the cathode active material is in the range of 2 µm to 10 µm. In some examples, the capacity of the cathode active material is in the range of 140 to 200 mAh / g (1C). In some examples, the BET value (Brunauer, Emmett, and Teller) of the cathode active material is in the range of 0.1 to 1.0 m 2 / G.

[0031] In some examples, the cathode active material comprises LiN x Al y Co 1-x-yO2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05). In some examples, a D50 particle size of the cathode active material is in the range of 2 µm to 10 µm. In some examples, the capacity of the cathode active material is in the range of 140 to 200 mAh / g (1C). In some examples, the BET value (Brunauer, Emmett, and Teller) of the cathode active material is in the range of 0.1 to 1.0 m 2 / G.

[0032] In some examples, the cathode active material comprises LiNi x Mn y Al z Co 1-x-y-z O2 (where 0.95 > x ≥ 0.33; y ≥ 0.01; and Z ≥ 0.01). In some examples, a D50 particle size of the cathode active material is in the range of 2 µm to 10 µm. In some examples, the capacity of the cathode active material is in the range of 140 to 180 mAh / g (1C). In some examples, the BET value (Brunauer, Emmett, and Teller) of the cathode active material is in the range of 0.1 to 1.0 m 2 / G.

[0033] In some examples, the cathode active material comprises an outer coating layer 68 ( Fig. 2B). In some examples, the outer coating layer 68 comprises lithium niobate (LiNbO3). In some examples, the outer coating layer 68 comprises 0.5 wt.% to 5 wt.% of the coated cathode active material.

[0034] In some examples, the cathode active material layer comprises cathode active material in the range of 40 wt.% to 90 wt.%, sulfide solid electrolytes in the range of 10 wt.% to 50 wt.%, an optional conductive additive (e.g., carbon black) in the range of 0 wt.% to 10 wt.% (e.g., 0.1 wt.% to 10 wt.%), and a binder (e.g., polytetrafluoroethylene (PTFE)) in the range of 0.1 wt.% to 3 wt.%. In some examples, the cathode current collector comprises an aluminum foil with a thickness in the range of 8 μm to 20 μm and a density in the range of 3.6 to 3.8 g / cm 3. In some examples, the capacity load is in the range of 1 to 6 mAh / cm 2 (with one-sided coating and at 1C and room temperature).

[0035] With reference to Fig. 3, one of the anode electrodes 40 is shown in more detail. The anode active material layer 42 comprises silicon active material 72 having a plurality of convex spherical surfaces 74. Silicon anodes having a plurality of convex spherical surfaces are described, for example, in commonly assigned U.S. patent applications Ser. Nos. XX / XXX,XXX and XX / XXX,XXX (C-5391 and C-53970), which are hereby incorporated by reference.

[0036] In some examples, the anode current collector 46 has a thickness in the range of 10 µm to 20 µm. In some examples, the roughened surface of the anode current collector 46 has a roughness (R a) in the range of 0.1 µm to 12 µm. In some examples, the anode current collector 46 is made of a material selected from a group consisting of copper, stainless steel, nickel, iron, titanium, tin, and their alloys.

[0037] In some examples, the anode active material is deposited onto the anode current collector 46 by physical vapor deposition (PVD). This creates the anode electrode without binders or conductive additives. In some examples, an outer surface of the silicon active material 72 includes a plurality of convex spherical surfaces 74 to increase the interface with the sulfide solid electrolyte of the S separators 32, which increases the lithium ion conduction paths and increases the performance of the solid-state battery cell. The plurality of convex spherical surfaces 74 also relieves the stress generated during cycling (e.g., by allowing expansion and contraction (as shown by arrows)) and improves the cyclability of the solid-state battery cell. Removing the binder, which acts as an ion insulator, increases performance.Removing the carbon additive prevents unwanted reactions, thereby extending the lifespan of the solid-state battery cell.

[0038] In some examples, a maximum thickness (from a peak of the plurality of convex spherical surfaces 74 to a valley of the roughened anode current collector 46) is in the range of 5 µm to 20 µm. In some examples, the distance between the peak and valley of the plurality of convex spherical surfaces 74 is in the range of 0.1 µm to 5 µm. In some examples, the A anode electrodes 40 have a total thickness in the range of 15 µm to 40 µm and a surface loading in the range of 3 to 10 mAh / cm 2 .

[0039] With reference to Fig. 4, the S separators 32 comprise a membrane with a sulfide solid electrolyte 82, a binder 84, an optional lithium salt, and a filler. In some examples, the sulfide solid electrolyte comprises lithium argyrodite (Li6PS5Cl or LPSCl for short). In some examples, the S separators 32 comprise sulfide solid electrolyte in the range of 85 to 99 wt.%, binder in the range of 1 to 10 wt.%, the optional lithium salt in the range of 0 wt.% to 5 wt.% (e.g., 0.1 wt.% to 5 wt.%), and a filler in the range of 0.1 wt.% to 1 wt.%. In some examples, the binder 84 comprises poly(ethylene oxide) (PEO) having an average molecular weight (Mv) in the range of 100,000 to 600,000 (nominal) and a transition temperature in the range of 60 to 70°C.

[0040] In some examples, the filler comprises an oxide-based sulfide solid electrolyte (e.g., garnet type, perovskite type, NASICON type, and / or LISICON type) or a ceramic oxide (Al2O3, SiO2, TiO2, and / or ZrO2) and has a particle diameter in the range of 2 nm to 200 nm. In some examples, the lithium salt is selected from a group consisting of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), etc. In some examples, the S separators 32 have a thickness in the range of 20 to 80 µm and an ionic conductivity in the range of 0.1 to 2 mS / cm at 30 °C. In some examples, the N / P ratio (capacitance ratio between anode and cathode) ranges from 1.5 to 2.8.

[0041] With reference to Fig. 5 and Fig. Figure 6 shows the discharge performance of an exemplary solid-state battery cell. The cathode active material layer comprises NMC532 / Li6PS5Cl / carbon black / PTFE binder in a ratio of 56 / 40 / 4 / 1 wt.% and a loading of 1.5 mAh / cm 2 . The S separators 32 comprise a sulfide membrane with LiPS5Cl / PEO / LiTFSI / SiO2 in a ratio of 95 / 5 / 0.5 / 0.2 wt% and a load of 3.7 mAh / cm 2 As you can see, the solid-state battery cell has a good discharge rate even at 10C.

[0042] With reference to Fig. 7 to 9 is the charging and charging / discharging performance of the exemplary solid-state battery cell from Fig. 5 and Fig. 6. As shown in Fig. 7 and Fig. As can be seen in Figure 8, the solid-state battery cell shows good fast charging capability. Fig. 9, the solid-state battery cell shows excellent cyclability after 600 cycles.

[0043] The foregoing description is merely illustrative and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be embodied in a variety of forms. While this disclosure includes specific examples, its true scope should not be limited thereto, since other modifications will become apparent upon review of the drawings, the specification, and the following claims. It is understood that one or more steps within a method may be performed in different orders (or simultaneously) without altering the principles of the present disclosure.Furthermore, although the embodiments are each described above as having specific features, any one or more of these features described with respect to one embodiment of the disclosure may be implemented and / or combined with features of any of the other embodiments, even if such combination is not expressly described. In other words, the described embodiments are not mutually exclusive, and interchanging one or more embodiments for one another remains within the scope of this disclosure.

[0044] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaging," "coupled," "adjacent," "beside," "on top of," "above," "below," and "disposed." Where a relationship between first and second elements is not explicitly described as "direct" in the above disclosure, that relationship may be a direct relationship, with no other intervening elements between the first and second elements, or an indirect relationship, with one or more intervening elements (either spatial or functional) between the first and second elements.The phrase "at least one of A, B or C" as used herein should be interpreted as logical (A OR B OR C) using a non-exclusive logical OR operator and should not be understood as "at least one of A, at least one of B and at least one of C".

[0045] In the figures, the direction of an arrow, indicated by the arrowhead, generally shows the flow of information (such as data or instructions) that is relevant to the illustration. For example, if element A and element B exchange a lot of information, but the information transferred from element A to element B is relevant to the illustration, the arrow can point from element A to element B. However, this unidirectional arrow does not mean that no other information is transferred from element B to element A. Furthermore, for information sent from element A to element B, element B can send requests or acknowledgments for the information to element A.

Claims

[1] Solid-state battery cell, comprising: A anode electrodes each having an anode active material layer arranged on an anode current collector, wherein the anode current collector has a roughened outer surface, the anode active material layer comprises silicon, and the outer surface of the anode active material layer has a plurality of convex spherical shapes; C cathode electrodes each having a cathode active material layer arranged on a cathode current collector, wherein the cathode active material layer comprises cathode active material and a sulfide solid electrolyte, wherein the cathode active material is selected from a group consisting of LiNi x Mn y Co 1-x-y O2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), LiN x Al y Co 1-x-y O2 (where 0.95 > x ≥ 0.33; and y ≥ 0.05), and LiNi x Mn y AlzCo 1-x-y-zO2 (where 0.95 > x ≥ 0.33; y ≥ 0.01; and Z ≥ 0.01); and S separators with a sulfide membrane, where A, C and S are integers greater than one. [2] The solid-state battery cell of claim 1, wherein the anode current collector is made of a material selected from a group consisting of copper, stainless steel, nickel, iron, titanium, tin, and alloys thereof. [3] Solid-state battery cell according to claim 1, wherein the anode current collector has a thickness in the range of 10 µm to 20 µm, and the roughened outer surface has a roughness in the range of 0.1 µm to 12 µm. [4] The solid-state battery cell according to claim 1, wherein the D50 particle size of the cathode active material is in the range of 2 µm to 10 µm. [5] A solid-state battery cell according to claim 1, wherein the cathode active material comprises an outer coating layer of lithium niobate (LiNbO3). [6] The solid-state battery cell of claim 5, wherein the outer coating layer comprises 0.5 wt% to 5 wt% of the cathode active material coated with the outer coating layer. [7] The solid-state battery cell of claim 1, wherein the sulfide solid electrolyte comprises Li6PS5Cl. [8] A solid-state battery cell according to claim 1, wherein the cathode active material layer: Cathode active material in the range of 40 wt% to 90 wt%, Sulfide solid electrolytes in the range of 10 wt% to 50 wt%, a conductive additive in the range of 0.1 wt% to 10 wt% and a binder in the range of 0.1 wt% to 3 wt%. [9] A solid-state battery cell according to claim 1, wherein the maximum thickness of the anode active material layer is in the range of 5 µm to 20 µm. [10] A solid-state battery cell according to claim 1, wherein the distance between the peak and the valley of the plurality of convex spherical surfaces is in the range of 0.1 µm to 5 µm.

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