Solid-state battery and electric equipment

Abstract

According to the solid-state battery and the electric equipment provided by the embodiment of the invention, the positive pole piece, the first solid-state electrolyte layer and the negative pole piece of the solid-state battery provided by the embodiment of the invention have the same active material layer length and width, so that the edges of the battery are flush, and collapse caused by a high-pressure forming process is avoided; meanwhile, the positive electrode active material layer and / or the negative electrode active material layer are / is provided with a thinned part, the thickness of the thinned part is smaller than that of the middle part, and the surface of the thinned part is covered with a second solid electrolyte layer, so that a thicker electronic insulating layer is formed on the thinned part, the risk of edge short circuit is reduced, no extra inert component without electrochemical activity is introduced, and the service life of the battery is prolonged. The battery design has higher energy density and rate capability; therefore, by adopting the solid-state battery provided by the invention, the problems of edge collapse, material falling, short circuit and other risks of the existing solid-state battery can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a solid-state battery and its electrical equipment. Background Technology

[0002] Currently, due to their non-flammable properties and the ability to achieve high specific capacity anodes, which is beneficial for improving battery energy density, all-solid-state batteries have attracted widespread attention in the industry.

[0003] In the traditional battery manufacturing process, in order to meet the process accuracy tolerance requirements of the stacking / winding process and avoid the risk of short circuit due to edge misalignment, the battery design adopts the design concept of negative-to-positive, that is, the size of the negative electrode coating is wider than the positive electrode coating area in all four directions, resulting in the so-called overhang area.

[0004] However, in order to form a tight packing and contact between solid particles, all-solid-state batteries generally include a high-pressure molding process in their manufacturing process, and they often need to be used under constrained conditions. Overhang design increases the risk of edge collapse, material loss, and short circuits in solid-state batteries during high-pressure molding and use. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a solid-state battery and an electrical device to solve the problems of edge collapse, material loss and short circuit in existing solid-state batteries.

[0006] To solve the above problems, the present invention is achieved through the following technical solution:

[0007] This invention proposes a solid-state battery, comprising a positive electrode, a first solid electrolyte layer, and a negative electrode. The positive electrode includes a positive current collector and a positive active material layer disposed on the positive current collector, and the negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector.

[0008] The positive electrode active material layer, the first solid electrolyte layer, and the negative electrode active material layer have the same length and the same width.

[0009] The positive electrode active material layer and / or the negative electrode active material layer include a middle portion and a thinned portion disposed around the middle portion. The thickness of the thinned portion is less than the thickness of the middle portion, and the surface of the thinned portion is covered with a second solid electrolyte layer.

[0010] Furthermore, in the solid-state battery, the thickness of the thinned portion decreases from the side closer to the middle portion to the side farther away from the middle portion, while the thickness of the second solid electrolyte layer increases.

[0011] Furthermore, in the solid-state battery, for any point within the thinned portion, the sum of the thickness of the thinned portion and the thickness of the second electrolyte layer is equal to the thickness of the intermediate portion.

[0012] Furthermore, in the solid-state battery, the thickness of the first solid electrolyte layer is 5µm to 800µm.

[0013] Furthermore, in the solid-state battery, the thickness of the side of the thinned portion away from the middle portion is 0-50% of the thickness of the middle portion.

[0014] Furthermore, in the solid-state battery, the width of the thinned portion is 0.1 mm to 40 mm.

[0015] Furthermore, in the solid-state battery, when the elastic modulus E1 of the electrode active material layer having the thinned portion in the positive electrode and the negative electrode, and the modulus E2 of the second solid electrolyte layer covering the thinned portion satisfy E1 / E2>5, the porosity P1 of the electrode having the thinned portion and the porosity P2 of the second solid electrolyte layer satisfy P2<P1<12%.

[0016] Furthermore, in the solid-state battery, the electronic conductivity σ of the second electrolyte layer is... e4 and the electronic conductivity σ of the first electrolyte layer e2 Satisfying σ e4 ≤σ e2 <10 -8 S / cm.

[0017] Furthermore, in the solid-state battery, the first solid electrolyte layer includes a first solid electrolyte, the second solid electrolyte layer includes a second solid electrolyte, and the first solid electrolyte and the second solid electrolyte are individually selected from one or more of oxide solid electrolyte, sulfide solid electrolyte, and halide solid electrolyte.

[0018] Furthermore, in the solid-state battery, the oxide solid electrolyte is selected from Li7La3Zr2O. 12 Li 10 One or more of Al(Ge,Si)2(PO4)7, wherein the sulfide solid electrolyte is selected from Li3PS4, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 6-x PS 5-x Cl1+x Li7P3S 11 The solid-state electrolyte is selected from one or more of Li4PS4I and Li7P2S8I, and the halide solid electrolyte is selected from one or more of Li3InCl6, Li2ZrO4, and Li3YCl6.

[0019] The present invention also proposes an electrical device, wherein the solid-state battery described above is included, and the solid-state battery serves as the power supply for the electrical device.

[0020] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0021] In this embodiment of the invention, the provided solid-state battery includes a positive electrode, a first solid electrolyte layer, and a negative electrode. The positive electrode includes a positive current collector and a positive active material layer disposed on the positive current collector. The negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector. The positive active material layer, the first solid electrolyte layer, and the negative active material layer have the same length and width. The positive active material layer and / or the negative active material layer include a middle portion and a thinned portion disposed around the middle portion. The thickness of the thinned portion is less than the thickness of the middle portion. The surface of the thinned portion is covered with a second solid electrolyte layer. The positive electrode and the first solid electrolyte layer are disposed thereon. The positive and negative electrode layers have the same length and width of active material layers, ensuring that the battery edges are flush and will not collapse due to high-pressure molding. Simultaneously, the positive and / or negative active material layers have thinned portions, with the thickness of the thinned portions being less than the thickness of the middle portions. A second solid electrolyte layer is covered on the surface of the thinned portions, forming a thicker electronic insulating layer, reducing the risk of edge short circuits. Furthermore, no additional electrochemically inactive inert components are introduced, resulting in higher energy density and rate performance in the battery design. Therefore, the solid-state battery provided by this invention can effectively improve the problems of edge collapse, material shedding, and short circuits in existing solid-state batteries.

[0022] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a solid-state battery provided in an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1-Positive electrode sheet, 11-Positive current collector, 12-Positive active material layer, 2-First solid electrolyte layer, 3-Negative electrode sheet, 31-Negative current collector, 32-Negative active material layer, 4-Second solid electrolyte layer, 51-Intermediate part, 52-Thinned part. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] In existing technologies, in order to form a tight packing and contact between solid particles, all-solid-state batteries generally include a high-pressure molding process in their manufacturing process, and they often need to be used under constrained conditions. If the overhang design in traditional battery manufacturing is still used, it will increase the risk of edge collapse, material loss, and short circuits in solid-state batteries during high-pressure molding and use.

[0028] To address the aforementioned problems, this invention provides a solid-state battery, wherein, as shown in the embodiments of the present invention... Figure 1 As shown, it includes a positive electrode 1, a first solid electrolyte layer 2, and a negative electrode 3. The positive electrode 1 includes a positive current collector 11 and a positive active material layer 12 disposed on the positive current collector 11. The negative electrode 3 includes a negative current collector 31 and a negative active material layer 32 disposed on the negative current collector 31. The positive active material layer 12, the first solid electrolyte layer 2, and the negative active material layer 32 have the same length and the same width. The positive active material layer 12 and / or the negative active material layer 32 include a middle portion 51 and a thinned portion 52 disposed around the middle portion 51. The thickness of the thinned portion 52 is less than the thickness of the middle portion 51. The surface of the thinned portion 52 is covered with a second solid electrolyte layer 4.

[0029] Figure 1 The diagram shows a solid-state battery containing two parallel battery cells, but it is only a schematic diagram. As long as the battery structure exhibits this feature, the actual number of cells can be arbitrary, and the embodiments of the present invention do not limit this.

[0030] In this design, the positive electrode active material layer, the first solid electrolyte layer, and the negative electrode active material layer are all the same length and width. This means the positive electrode sheet, the first solid electrolyte layer, and the negative electrode sheet have the same edge dimensions, ensuring the battery edges are flush and preventing collapse during the high-pressure forming process. Figure 1 As shown, the dimensions of the positive electrode, the first solid electrolyte layer, and the negative electrode satisfy: W1 = W2 = W3; where W1 is the length of the positive active material layer, W2 is the length of the first solid electrolyte layer, and W3 is the length of the negative active material layer, or W1 is the width of the positive active material layer, W2 is the width of the first solid electrolyte layer, and W3 is the width of the negative active material layer.

[0031] The positive electrode active material layer and / or negative electrode active material layer include a middle part and a thinned part arranged around the middle part. The thickness of the thinned part is less than the thickness of the middle part. The surface of the thinned part is covered with a second solid electrolyte layer so that the thinned part has a thicker electronic insulating layer, which reduces the risk of edge short circuit and does not introduce additional inert components without electrochemical activity, resulting in higher energy density and rate performance in the battery design.

[0032] Therefore, the solid-state battery provided by this invention can effectively improve the problems of edge collapse, material loss, and short circuits in existing solid-state batteries.

[0033] Optionally, in one embodiment, both the positive electrode active material layer and the negative electrode active material layer are thinned active material layers, that is, there are thinned portions at the edges, so that the thickness variation curve of the thinned portion between the positive electrode sheet and the negative electrode sheet is more suitable, which can meet the design of a better ratio (N / P) of negative electrode discharge reversible capacity to positive electrode discharge capacity at the edge.

[0034] In this implementation, such as Figure 1 As shown, the positive electrode active material layer 12 is composed of a positive electrode thinning portion 152 and a positive electrode intermediate portion 151, and the negative electrode active material layer 32 is composed of a negative electrode thinning portion 352 and a negative electrode intermediate portion 351.

[0035] Alternatively, in one embodiment, the thickness of the thinned portion decreases from the side closer to the middle portion to the side farther from the middle portion, while the thickness of the second solid electrolyte layer increases, which enables the outer side of the thinned portion to have a thicker electronic insulating layer, further reducing the risk of edge short circuits.

[0036] Optionally, in one specific embodiment, for any point within the thinned portion, the sum of the thickness of the thinned portion and the thickness of the second solid electrolyte layer is equal to 95% to 105% of the thickness of the middle portion. This ensures that the thickness of the edge and the middle portion does not deviate too much during the molding and testing process of the battery, maintaining thickness consistency. Consequently, the thinned portion can be in close contact with the first electrolyte layer, avoiding edge collapse and material loss during high-pressure molding and use.

[0037] Optionally, in one specific embodiment, for any point within the thinned portion, the sum of the thickness of the thinned portion and the thickness of the second electrolyte layer is equal to the thickness of the middle portion, so that the thickness of the edge and the middle of the battery is consistent during the molding and testing process, and the thinned portion can make closer contact with the first electrolyte layer, avoiding edge collapse and material loss during high-pressure molding and use.

[0038] This specific implementation method includes the following three situations:

[0039] Case 1: The negative electrode active material does not have a thinning section, while the positive electrode active material layer includes a middle part and a thinning section around the middle part. The thickness of the thinning section is less than the thickness of the middle part. The surface of the thinning section is covered with a second solid electrolyte layer. For any point within the thinning section, the sum of the thickness of the thinning section and the thickness of the second electrolyte layer is equal to the thickness of the middle part of the positive electrode active material layer.

[0040] In this scenario, by covering the surface of the thinned portion with a second solid electrolyte layer of the positive electrode active material layer, a thicker electronic insulating layer is formed in the thinned portion, reducing the risk of edge short circuits.

[0041] Scenario 2: The positive electrode active material does not have a thinning section, while the negative electrode active material layer includes a middle part and a thinning section around the middle part. The thickness of the thinning section is less than the thickness of the middle part. The surface of the thinning section is covered with a second solid electrolyte layer. For any point within the thinning section, the sum of the thickness of the thinning section and the thickness of the second electrolyte layer is equal to the thickness of the middle part of the positive electrode active material layer.

[0042] In this second scenario, by covering the surface of the thinned portion with a second solid electrolyte layer of negative electrode active material layer, a thicker electronic insulating layer is formed in the thinned portion, reducing the risk of edge short circuits.

[0043] Case 3: The positive electrode active material layer includes a middle part and a thinned part arranged around the middle part. The thickness of the thinned part is less than the thickness of the middle part. The surface of the thinned part is covered with a second solid electrolyte layer. For any point in the thinned part, the sum of the thickness of the thinned part and the thickness of the second electrolyte layer is equal to the thickness of the middle part of the positive electrode active material layer.

[0044] The negative electrode active material layer includes a middle part and a thinned part arranged around the middle part. The thickness of the thinned part is less than the thickness of the middle part. The surface of the thinned part is covered with a second solid electrolyte layer. For any point in the thinned part, the sum of the thickness of the thinned part and the thickness of the second electrolyte layer is equal to the thickness of the middle part of the negative electrode active material layer.

[0045] In this third scenario, by covering the thinned portions of both the positive and negative electrode active material layers with a second solid electrolyte layer, a thicker electronic insulating layer is formed in the thinned portions, reducing the risk of edge short circuits.

[0046] The first electrolyte layer is disposed between the positive and negative electrode plates, serving to isolate electron transport between the two plates and to conduct lithium ions. Optionally, such as Figure 1As shown, the thickness L2 of the first solid electrolyte layer is 5µm to 800µm, which can not only effectively reduce the risk of short circuit between the positive and negative electrode plates, but also avoid excessive impedance, which would affect battery performance and reduce battery energy density. Optionally, in one specific embodiment, L2 is 10µm to 30µm, for example, a value within the range of 10µm, 15µm, 20µm, 25µm, and 30µm, or any two of them.

[0047] Optionally, in one embodiment, the thickness of the side of the thinned portion away from the middle portion is 0 to 50% of the thickness of the middle portion, that is, the thickness of the outermost part of the thinned portion is 0 to 50% of the thickness of the middle portion, so as to provide sufficient space to set a sufficiently thick second solid electrolyte layer, thereby ensuring the overall thickness of the electronic insulation layer in the edge region and effectively suppressing edge short circuits.

[0048] For example, as shown in Figure 1, when both the positive electrode active material layer and the negative electrode active material layer have edge thinning regions, the thickness H of the outermost thinned portion of the positive electrode active material layer is... 1A The thickness L1 of its middle part satisfies 0 ≤ H 1A / L1≤50%, the outermost thickness H of the thinned portion of the negative electrode active material layer 3A The thickness L3 of its middle part satisfies 0 ≤ H 3A / L3≤50%.

[0049] Optionally, in one embodiment, the width of the thinned portion is 0.1 mm to 40 mm, where the width is the distance between the side of the thinned portion away from the middle portion and the middle portion. When the width of the thinned portion is within the above range, edge short circuits can be effectively limited while also ensuring battery energy density. Optionally, the width of the thinned portion can be one or any two of the following: 0.1 mm, 0.5 mm, 1 mm, 5 mm, 10 mm, 20 mm, 30 mm, and 40 mm.

[0050] In this embodiment of the invention, the second solid electrolyte layer is used to offset the height difference between the thinned portion and the middle portion, while making the thinned portion form a thicker electronic insulating layer, thereby reducing the risk of edge short circuits.

[0051] Optionally, in one embodiment, when the elastic modulus E1 of the active material layer and the modulus E2 of the second solid electrolyte layer covering it in the thinned electrode sheet satisfy E1 / E2>5, the porosity P1 of the thinned electrode sheet and the porosity P2 of the second solid electrolyte layer satisfy P2<P1<12%, thereby keeping the deformation rate of the compacted thinned electrode sheet and the second solid electrolyte layer close, and thus maintaining the consistency of the overall thickness of the battery.

[0052] When E1 / E2 < 5, the porosity of both can be disregarded; alternatively, P2 < P1 < 12% results in greater consistency in the thickness of the middle and edge regions of the battery.

[0053] Preferably, in one embodiment, the elastic modulus E of the positive electrode active material layer in the thinned positive electrode sheet is... 1p and the modulus E of the second solid electrolyte layer covering it 2p The space satisfies E 1p / E 2p When the porosity P of the thinned positive electrode active material layer is greater than 5, the porosity P of the thinned positive electrode sheet is greater than 5. 1p The porosity P of the second solid electrolyte layer 2p Satisfy P 2p <P 1p The deformation rate is less than 12%, ensuring that the deformation rates of the compacted, thinned positive electrode sheet and the second solid electrolyte layer remain similar, thus maintaining the consistency of the overall battery thickness. Since the positive electrode sheet is relatively thick in solid-state batteries, its parameters have a significant impact on battery performance. Meeting the above range for both the positive electrode sheet and the second solid electrolyte layer contributes more to battery performance.

[0054] Under the aforementioned modulus relationship, during the battery restraint test, the deformation of the electrolyte material in the second solid electrolyte layer is much larger than that of the electrode. It is necessary to ensure that the second solid electrolyte layer has a lower porosity so that it does not deform excessively under pressure. This prevents a large deviation between the deformation of the second solid electrolyte layer and the active material layer on the electrode, which could lead to a thickness mismatch between the middle and edge regions of the battery. Therefore, even when the positive electrode active material layer has a thinned section, the thickness relationship between the second solid electrolyte layer and the positive electrode active material layer should be maintained at 95% ≤ (H). 1a +H 4a Within the range of ) / L1≤105%, and when the negative electrode active material layer has a thinned portion, the thickness relationship between the second solid electrolyte layer and the negative electrode active material layer is maintained at 95%≤(H) / L1≤105%. 3a +H 4b Within the range of ) / L3 ≤ 105%; where H 1a H 4a These represent the thickness of the thinned portion at any point in the positive electrode active material layer and the thickness of the second solid electrolyte layer, respectively. 3a H 4b These represent the thickness of the thinned portion at any point in the negative electrode active material layer and the thickness of the second solid electrolyte layer, respectively.

[0055] Optionally, in one embodiment, the electronic conductivity σ of the second electrolyte layer is... e4 and the electronic conductivity σ of the first electrolyte layer e2 Satisfying σ e4 ≤σ e2<10 -8 S / cm can effectively ensure good electronic insulation performance at the edges.

[0056] In this embodiment of the invention, the first solid electrolyte layer includes a first solid electrolyte, and the second solid electrolyte layer includes a second solid electrolyte. Optionally, in one embodiment, the first solid electrolyte and the second solid electrolyte are each selected from one or more of phosphate-based solid electrolytes, oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

[0057] In this embodiment of the invention, a low contact resistance is selected between the first electrolyte layer and the second electrolyte layer, thereby reducing the overall battery impedance. Optionally, the first solid electrolyte and the second solid electrolyte are the same, resulting in even lower contact resistance, thus significantly reducing the overall battery impedance.

[0058] Optionally, in one specific embodiment, the phosphate-based solid electrolyte is selected from lithium aluminum titanium phosphate (LATP), and the oxide solid electrolyte is selected from Li7La3Zr2O. 12 Li 10 One or more of Al(Ge,Si)2(PO4)7, and the sulfide solid electrolyte is selected from Li3PS4, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 6-x PS 5-x Cl 1+x Li7P3S 11 One or more of Li4PS4I and Li7P2S8I, and the halide solid electrolyte is selected from one or more of Li3InCl6, Li2ZrO4, and Li3YCl6.

[0059] When using LATP oxide electrolyte, its modulus is close to that of the positive electrode, the ratio of the porosity of the edge electrolyte region to that of the positive electrode does not need to be specially controlled, and its modulus is higher and its structure is more stable, which is beneficial to improving cycle stability. However, its ionic conductivity is lower, which affects the battery's first discharge capacity.

[0060] In this embodiment of the invention, the above-mentioned positive electrode active material layer comprises a positive electrode active material, a third solid electrolyte, a conductive agent, and a polymer binder, wherein the proportion of the positive electrode active material is 40-94 wt%, the proportion of the third solid electrolyte is 5-60 wt%, the proportion of the conductive agent is 0-10%, and the proportion of the binder is 0.1-10%.

[0061] The aforementioned positive electrode active materials include one or more of the following: olivine-based, layered oxide-based, spinel-based, sulfur-based, and sulfide-based positive electrode materials. Examples of olivine-based materials include LiFePO4; layered oxide-based materials include lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), or LiCoO2; and spinel-based materials include LiMn2O4 and Li4Ti5O4. 12 The cathodes include sulfur-containing cathodes and sulfide-containing cathodes such as S8, FeS2, and CuS; the conductive agent is a commonly used conductive agent for cathodes, such as acetylene black, carbon nanotubes, carbon fibers, and carbon black; the third solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes; the polymer binder can be one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), polyacrylate, polyacrylic acid (PAA), alkyl cellulose, and polyethylene oxide (PEO), hydrogenated nitrile rubber, etc.

[0062] In some embodiments, the positive electrode sheet is prepared as follows: the components used to prepare the positive electrode sheet, such as the positive active material, binder and any other components, are dispersed in a solvent such as N-methylpyrrolidone to form a positive electrode slurry; the positive electrode slurry is coated on both sides of a positive electrode current collector such as an aluminum foil; after baking, rolling, cutting and other processes, the positive electrode sheet can be obtained.

[0063] In this embodiment of the invention, the aforementioned negative electrode active material layer comprises a negative electrode active material, which may be a negative electrode active material used in batteries, capable of absorbing and releasing metal ions (such as lithium ions), for example selected from metal negative electrode materials or non-metal negative electrode materials; the metal negative electrode material is preferably lithium metal or lithium metal alloy; the non-metal negative electrode material is preferably any one or a combination of at least two of hard carbon, soft carbon, graphite, silicon suboxide, silicon-carbon composite, Si, and silicon alloy.

[0064] Optionally, in one embodiment, when the above-mentioned negative electrode active material is selected from non-metallic negative electrode materials, the above-mentioned negative electrode sheet further includes a conductive agent, a binder, and a fourth solid electrolyte. The conductive agent is selected from at least one of acetylene black, Super P, Super S, graphene, carbon fiber, carbon nanotubes, and Ketjen black. The binder is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, and ethylene oxide-propylene oxide copolymer. The fourth solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

[0065] Optionally, in one embodiment, the aforementioned negative electrode active material layer further includes a plasticizer, wherein the plasticizer is selected from at least one of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tetrapropylene glycol dimethyl ether, 1,3-dioxolane, 1,4-dioxane, propylene carbonate, ethylene carbonate, diethyl carbonate or dimethyl carbonate, succinate, and adiponitrile.

[0066] In some embodiments, the negative electrode sheet is prepared as follows: the components used to prepare the negative electrode sheet, such as the negative electrode active material, binder and conductive agent, are dispersed in a solvent such as deionized water to form a negative electrode slurry; the negative electrode slurry is coated on both sides of a negative electrode current collector such as copper foil; after baking, rolling, cutting and other processes, the negative electrode sheet can be obtained.

[0067] In practical applications, the negative electrode sheet, polymer electrolyte membrane and positive electrode sheet are stacked in sequence and wound to obtain the core, then sealed and sorted to obtain the solid-state battery mentioned above.

[0068] After the second sealing, isostatic pressing can be used, with a molding pressure of 400–600 MPa and a temperature of 80–150°C. However, lower molding pressures affect the structural strength, resulting in slightly inferior performance of the solid-state battery.

[0069] The present invention also proposes an electrical device, wherein the solid-state battery described above is included, and the solid-state battery serves as the power supply for the electrical device.

[0070] The above-described solid-state battery embodiments and electrical device embodiments include the aforementioned polymer electrolyte and achieve the same technical effects. To avoid repetition, they will not be described again here. For relevant details, please refer to the description of the polymer electrolyte embodiments.

[0071] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0072] The present invention will be described in detail below through embodiments.

[0073] Test method:

[0074] (1) Thinning section size test: The electrode edge section is cut out using focused ion beam (FIB), and the thickness of the electrode coating area is observed using SEM. The position where the thickness is 95% of the electrode center thickness is located from the electrode edge. This distance is measured using a distance measuring tool and is the width of the thinning section.

[0075] (2) Test method for elastic modulus: The test is carried out by a nanoindenter. The nanodiamond indenter applies a load to the surface of the electrode, and the load-displacement curve is recorded by a computer, and the elastic modulus information of the corresponding material layer is output.

[0076] (3) Porosity test method: The material layer in the electrode is cut into a circular disc with a thickness of L and a diameter of D, and the mass of the disc is weighed M. Combined with the weighted average density ρ of all materials in the material layer, 理论 According to porosity P = (1 - 4M / ρ) 理论 πD 2 Calculated using L)×100%.

[0077] (4) Electronic conductivity testing method: 100 mg of powder corresponding to the electrolyte layer was weighed in an argon atmosphere glove box. An electrolyte sheet was formed using a mold with a diameter of D = 10 mm under 120 MPa pressure. The thickness L of the electrolyte sheet was recorded. Carbon-coated aluminum foil discs were added to both sides of the electrolyte sheet, and an Al|solid electrolyte|Al battery was assembled under a pressure of 380 MPa. The DC internal resistance R was tested and calculated using an electrochemical workstation (VMP-300) with DC polarization. The electronic conductivity σ was then used to determine the electronic conductivity. e =4L / πRD 2 Calculated.

[0078] (5) First cycle capacity test: The prepared battery was connected to the charge and discharge test cabinet under the constraint of a 20 MPa pressure fixture, charged to 100% SOC at a rate of 0.1C, and the charging capacity was recorded; after standing for 5 minutes, it was discharged to 0 SOC at a rate of 0.1C and the discharge capacity was recorded as the first cycle capacity.

[0079] (6) First-cycle efficiency test: Calculate the percentage of discharge capacity to charge capacity in the above process, and record it as the first-cycle efficiency.

[0080] (7) Cyclic performance test: The battery is charged and discharged at a rate of 0.33C until the battery discharge capacity is reduced to 80% of the initial discharge capacity. The number of cycles at that time is recorded as the cycle performance.

[0081] Example 1

[0082] (1) Preparation of positive electrode sheet

[0083] Single-crystal LiNi, the positive electrode active material 0.9 Co 0.05 Mn0.05 O2, solid electrolyte Li6PS5Cl1, binder hydrogenated nitrile butadiene rubber (HNBR), and conductive agent Super P are mixed evenly in N,N-dimethylformamide at a mass ratio of 80:2:1:1. The slurry is then coated onto an aluminum current collector using a scraper, with the slurry thickness decreasing within a 10mm edge width area as a thinning section. The outermost slurry thickness is 20% of the thickness of the central area. The mixture is then dried at 60℃ for 1 hour and then at 80℃ for 3 hours to obtain a positive electrode sheet. The D50 of the positive electrode active material is 3µm, and the D50 of the solid electrolyte is 1.5µm.

[0084] (2) Preparation of the first solid electrolyte layer

[0085] The first solid electrolyte layer was prepared by mixing solid electrolyte Li6PS5Cl1 and binder HNBR at a mass ratio of 99:1, wherein the particle size of the solid electrolyte was 3 μm.

[0086] (3) Preparation of negative electrode sheet

[0087] A negative electrode sheet with the same size as the positive electrode sheet was prepared by using pure Si material, hydrogenated nitrile butadiene rubber (HNBR) as binder, and conductive agent Super P in a mass ratio of 85:10:5. The slurry thickness was controlled to decrease in a region with an edge width of 10 mm as a thinning part, and the outermost slurry thickness was 20% of the slurry thickness in the central region.

[0088] (4) Preparation of the second solid electrolyte layer

[0089] solid electrolyte Li6PS5Cl 0.5 Br 0.5 The binder PVDF-HFP is mixed at a mass ratio of 90:10 and then coated onto the thinned portions of the positive and negative electrode sheets until the surface is flush with the slurry in the central area, thus preparing the second solid electrolyte layer.

[0090] (5) Solid-state battery fabrication

[0091] In an argon-filled glove box, the positive electrode, the first solid electrolyte layer, and the negative electrode are aligned and assembled in that order. Then, isostatic pressing is performed under a pressure of 500 MPa and a temperature of 80°C to produce a solid-state battery.

[0092] Example 2

[0093] The only difference from Example 1 is that in step (5), the pressure of isostatic pressing is adjusted to 400 MPa and the temperature to 80°C.

[0094] Example 3

[0095] The only difference from Example 1 is that in step (5), the pressure of isostatic pressing is adjusted to 600 MPa and the temperature to 80°C.

[0096] Example 4

[0097] The only difference from Example 1 is that in step (5), the pressure of isostatic pressing is adjusted to 100 MPa and the temperature to 25°C.

[0098] Example 5

[0099] The only difference from Example 1 is that, in step (4), the solid electrolyte is adjusted to the LATP type, specifically Li 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0100] Example 6

[0101] The only difference from Example 5 is that in step (5), the pressure of isostatic pressing is adjusted to 400 MPa and the temperature to 80°C.

[0102] Example 7

[0103] The only difference from Example 1 is that, in step (4), the solid electrolyte is adjusted to Li7P3S. 11 .

[0104] Example 8

[0105] The only difference from Example 1 is that in steps (1) and (3), the slurry thickness decreases in the area where the edge width is controlled to be 5 mm as a thinning part.

[0106] Example 9

[0107] The only difference from Example 1 is that in steps (1) and (3), the slurry thickness decreases in the area where the edge width is controlled to be 0.1 mm as a thinning section.

[0108] Example 10

[0109] The only difference from Example 1 is that in steps (1) and (3), the slurry thickness decreases in the area with a controlled edge width of 40 mm as a thinning section.

[0110] Example 11

[0111] The only difference from Example 1 is that in steps (1) and (3), the thickness of the slurry on the outermost part of the thinned section is controlled to be 40% of the thickness of the slurry in the central region.

[0112] Example 12

[0113] The difference between Example 11 and Example 1 is that, in steps (1) and (3), the thickness of the slurry on the outermost part of the thinned section is controlled to be 50% of the thickness of the slurry in the central region.

[0114] Example 13

[0115] The difference from Example 1 is that in steps (1) and (3), the thickness of the slurry on the outermost part of the thinned section is controlled to be 70% of the thickness of the slurry in the central region.

[0116] Example 14

[0117] The difference between Example 14 and Example 1 is that in steps (1) and (2), the particle size D50 of the solid is adjusted to 5 μm.

[0118] Comparative Example 1

[0119] The difference between Comparative Example 1 and Example 1 is that step (4) is omitted.

[0120] Comparative Example 2

[0121] The difference between Comparative Example 1 and Example 1 is that step (4) is omitted, and the thinning part is not provided in steps (1) and (3).

[0122] The components and parameters of the solid-state batteries in each embodiment and comparative example are shown in Table 1.

[0123] The solid-state batteries prepared in each embodiment and comparative example were subjected to tests on the thinned portion size, elastic modulus, porosity, and electronic conductivity. The test data are shown in Table 1.

[0124] The solid-state batteries prepared in each embodiment and comparative example were subjected to first-cycle capacity testing, first-cycle efficiency testing, and cycle performance testing. The test data are shown in Table 2.

[0125] Table 1

[0126]

[0127] Table 2

[0128]

[0129] Based on the above test data, thinning the active material layer at the edges of the positive and negative electrode plates and covering it with a solid electrolyte layer can form a thicker electronic insulation layer between the positive and negative electrode plates, reducing the risk of edge short circuits and achieving better cycle performance.

[0130] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0131] The present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A solid-state battery, characterized in that, It includes a positive electrode sheet, a first solid electrolyte layer, and a negative electrode sheet. The positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector. The negative electrode sheet includes a negative current collector and a negative active material layer disposed on the negative current collector. The positive electrode active material layer, the first solid electrolyte layer, and the negative electrode active material layer have the same length and the same width. The positive electrode active material layer and / or the negative electrode active material layer include a middle portion and a thinned portion disposed around the middle portion. The thickness of the thinned portion is less than the thickness of the middle portion, and the surface of the thinned portion is covered with a second solid electrolyte layer.

2. The solid-state battery according to claim 1, characterized in that, The thickness of the thinned portion decreases from the side closest to the middle portion to the side furthest from the middle portion, while the thickness of the second solid electrolyte layer increases.

3. The solid-state battery according to claim 1 or 2, characterized in that, For any point within the thinned portion, the sum of the thickness of the thinned portion and the thickness of the second solid electrolyte layer is equal to 95% to 105% of the thickness of the intermediate portion.

4. The solid-state battery according to claim 3, characterized in that, For any point within the thinned portion, the sum of the thickness of the thinned portion and the thickness of the second electrolyte layer is equal to the thickness of the intermediate portion.

5. The solid-state battery according to any one of claims 1 to 4, characterized in that, The thickness of the first solid electrolyte layer is 5µm to 800µm.

6. The solid-state battery according to any one of claims 1 to 5, characterized in that, The thickness of the thinned portion on the side away from the middle portion is 0-50% of the thickness of the middle portion.

7. The solid-state battery according to any one of claims 1 to 6, characterized in that, The width of the thinned portion is 0.1 mm to 40 mm.

8. The solid-state battery according to any one of claims 1 to 7, characterized in that, When the elastic modulus E1 of the electrode active material layer with the thinned portion in the positive electrode and the electrode negative electrode, and the elastic modulus E2 of the second solid electrolyte layer covering the thinned portion satisfy E1 / E2>5, the porosity P1 of the electrode with the thinned portion and the porosity P2 of the second solid electrolyte layer satisfy P2<P1<12%.

9. The solid-state battery according to any one of claims 1 to 8, characterized in that, The electronic conductivity σ of the second electrolyte layer e4 and the electronic conductivity σ of the first electrolyte layer e2 Satisfying σ e4 ≤σ e2 <10 -8 S / cm.

10. The solid-state battery according to claim 9, characterized in that, The first solid electrolyte layer includes a first solid electrolyte, and the second solid electrolyte layer includes a second solid electrolyte. The first solid electrolyte and the second solid electrolyte are individually selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

11. The solid-state battery according to claim 10, characterized in that, The oxide solid electrolyte is selected from Li7La3Zr2O 12 Li 10 One or more of Al(Ge,Si)2(PO4)7, wherein the sulfide solid electrolyte is selected from Li3PS4, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 6-x PS 5-x Cl 1+x Li7P3S 11 The solid-state electrolyte is selected from one or more of Li4PS4I and Li7P2S8I, and the halide solid electrolyte is selected from one or more of Li3InCl6, Li2ZrO4, and Li3YCl6.

12. An electrical appliance, characterized in that, The device includes a solid-state battery as described in any one of claims 1 to 11, wherein the solid-state battery serves as the power supply for the electrical device.

Images