Anti-short-circuit positive pole piece and all-solid-state battery comprising same

Abstract

The utility model provides an anti-short-circuit positive pole piece and an all-solid-state battery comprising the same, and relates to the technical field of solid-state batteries. The all-solid-state battery comprises an anti-short-circuit positive pole piece, and the anti-short-circuit positive pole piece comprises a positive pole material central area, an edge solid electrolyte protection area of the positive pole material central area and a surface solid electrolyte protection layer. According to the all-solid-state battery, the surface and the edge of the positive electrode coating are covered with the solid electrolyte protection layer in advance, so that the problem of battery short circuit caused by shear stress generated by the positive electrode to the negative electrode in the whole life cycle of the all-solid-state battery can be solved, and meanwhile, the lamination efficiency and the alignment degree are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to solid battery technical field, concretely relates to a positive pole piece of preventing short circuit and full solid battery containing the pole piece. BACKGROUND

[0002] Full solid battery is the battery containing solid electrolyte, because full solid battery uses solid electrolyte to replace traditional liquid electrolyte, makes full solid battery's safety performance greatly promotes. However, because each component and interface in full solid battery are solid-solid contact, so the contact effect is all very poor. In order to let the battery can normally charge and discharge, and release the performance satisfying requirement, in the assembly and use process, generally all want to pass through the external application huge pressure to assist the battery, and the assembly pressure will be at 200MPa~600MPa, and the test pressure will be at 15~45MPa.

[0003] Because the lithium ion conduction between the positive pole and the negative pole needs overhang (some design excess part or redundancy design of battery monomer or battery pack in physical structure, performance index or safety design) area, so usually the positive pole will be a little smaller than the negative pole size, when the pressure is added after the lamination assembly, because the pressure exerting characteristic of isostatic pressing and the edge gap caused by the size difference between the positive pole and the negative pole, the negative pole will be bent inward after being stressed, causing the pole piece damage short circuit. In the test process, due to the external pressure usually being plane pressure, the flatness of the pole piece is uneven, and the alignment of the stacked positive pole and negative pole is inconsistent, which can cause uneven stress on the pole piece, thereby causing cracks on the electrolyte film, damage, leading to battery short circuit, and obviously reducing the yield of the battery. The prior art still has deficiencies for solving the problem of battery short circuit caused by the shear stress of the positive pole to the negative pole. UTILITARIAN CONTENT

[0004] In order to solve the problem of battery short circuit caused by the shear stress of the positive pole to the negative pole in the whole life cycle of the full solid battery. The utility model applies electrolyte protective layer on the center area and surface of the positive pole material four edges, and the edge protection area can ensure the existence of the overhang area, and can also play a filling role on the gap between the positive pole and the negative pole when the pole piece is assembled and tested under pressure. The surface solid electrolyte protective layer can make up for the unevenness of the positive pole coating, and reduce or eliminate the cracks and damage of the electrolyte film during assembly and testing, so that the overall stress of the battery is uniform.

[0005] One of the purposes of the utility model is to provide a positive pole piece for preventing short circuit.

[0006] The second purpose of the utility model is to provide a full solid battery comprising the above-mentioned positive pole piece.

[0007] In order to achieve the above-mentioned purposes of the utility model, the following technical solutions are adopted:

[0008] The utility model provides a positive pole piece of preventing short circuit, and the positive pole piece of preventing short circuit includes: positive pole current collector, both sides of positive pole current collector are sequentially provided with positive pole coating and surface solid state electrolyte protection layer, the positive pole coating includes positive pole material center area and edge solid state electrolyte protection area, the edge solid state electrolyte protection area surrounds the four around positive pole material center area, and the surface solid state electrolyte protection layer completely covers on positive pole material center area and edge solid state electrolyte protection area.

[0009] Referring to Figure 1 The positive pole piece of preventing short circuit includes positive pole current collector 1, both sides of positive pole current collector 1 are sequentially provided with positive pole coating 2 and surface solid state electrolyte protection layer 3, positive pole coating 2 is divided into positive pole material center area 21 and edge solid state electrolyte protection area 22, edge solid state electrolyte protection area 22 surrounds the four around positive pole material center area 21 (four edges, frame structure), and is covered with surface solid state electrolyte protection layer 3.

[0010] The positive pole current collector 1 can be aluminum foil or the like.

[0011] The positive pole material center area 21 can be a positive pole active material layer of a conventional all-solid-state battery, for example, composed of a positive pole active material, a solid state electrolyte, a conductive agent and a binder.

[0012] The edge solid state electrolyte protection area 22 is an edge protection area formed by a solid state electrolyte.

[0013] The surface solid state electrolyte protection layer 3 is a surface protection layer formed by a solid state electrolyte.

[0014] The solid state electrolyte is a solid state electrolyte of a conventional all-solid-state battery, for example, a sulfide electrolyte, an oxide electrolyte, a halide electrolyte, a polymer electrolyte, etc., and a typical example is lithium phosphorus sulfur chloride (Li6PS5Cl).

[0015] In some embodiments, the thickness of the edge solid state electrolyte protection area is 1-300 μm, which is the same as the thickness of the positive pole material center area after rolling;

[0016] In some embodiments, the width of the edge solid state electrolyte protection area is 0.5-5 mm, so that the size of the positive pole piece is consistent with the size of the negative pole coating area. Preferably, the frame structure of the edge solid state electrolyte protection area is of equal width.

[0017] In some embodiments, the thickness of the surface solid state electrolyte protection layer is 1-100 μm;

[0018] In some embodiments, the length of the surface solid-state electrolyte protective layer is 1-10 mm longer than the length of the positive electrode material central region, and the width of the surface solid-state electrolyte protective layer is 1-10 mm wider than the width of the positive electrode material central region.

[0019] The short-circuit prevention positive electrode sheet can be prepared by the following method:

[0020] The positive electrode active material, the solid-state electrolyte, the conductive agent, and the binder are fully mixed and dispersed to obtain a positive electrode material slurry;

[0021] The positive electrode material slurry is coated on both sides of the positive electrode current collector, and then rolled to obtain a positive electrode material central region;

[0022] The solid-state electrolyte and the binder are fully mixed and dispersed to obtain a solid-state electrolyte slurry;

[0023] The solid-state electrolyte slurry is coated around the edges of the positive electrode material central region by extrusion coating to obtain an edge solid-state electrolyte protective region; and the solid-state electrolyte slurry is coated on the surface of the positive electrode material central region and the edge solid-state electrolyte protective region by extrusion coating to form a surface solid-state electrolyte protective layer.

[0024] In a second aspect, the utility model provides a kind of full solid battery, including solid-state electrolyte layer, and the short-circuit prevention positive electrode sheet and negative electrode sheet of alternative stacking described above, the solid-state electrolyte layer is between the short-circuit prevention positive electrode sheet with the negative electrode sheet.

[0025] The size of the solid-state electrolyte layer is equal to the size of the negative electrode sheet, and the size of the negative electrode sheet is equal to the size of the short-circuit prevention positive electrode sheet.

[0026] The negative electrode sheet and the solid-state electrolyte layer are conventional negative electrode sheets and solid-state electrolytes in full solid batteries.

[0027] The full solid battery can be prepared by the following method:

[0028] The solid-state electrolyte layer is compounded on both sides of the negative electrode sheet to obtain a composite negative electrode sheet: for example, a negative electrode active material, a sulfide electrolyte, a conductive agent and a binder are fully mixed and dispersed to obtain a negative electrode material slurry; the negative electrode material slurry is coated on the negative electrode current collector to obtain a negative electrode sheet; the solid-state electrolyte and the binder are fully mixed and dispersed to obtain a solid-state electrolyte slurry; the solid-state electrolyte slurry is coated on the positive electrode current collector to obtain a solid-state electrolyte layer; and the solid-state electrolyte layer is transferred on both sides of the negative electrode sheet by rolling or isostatic pressing to obtain a composite negative electrode sheet.

[0029] Then the short-circuit prevention positive pole piece and the composite negative pole piece are stacked through a lamination process to obtain a bare battery cell; the bare battery cell is welded with a tab, placed into an aluminum plastic film, and vacuum packaged; an isostatic pressing process is used to obtain a full solid-state battery.

[0030] Technical effects:

[0031] The short-circuit prevention positive pole piece of the utility model includes a positive material center area, an edge solid-state electrolyte protection area and a surface solid-state electrolyte protection layer of the positive material center area, a solid-state electrolyte protection layer is pre-covered on the surface and the edge of the positive coating layer, the short circuit of the battery caused by the shear stress of the positive electrode to the negative electrode in the whole life cycle of the full solid-state battery can be solved, and the lamination efficiency and the alignment degree are improved.

[0032] The utility model has been described in detail in the foregoing, but the above-mentioned implementation is only illustrative in nature, and is not intended to limit the utility model. In addition, this paper is not limited by any theory described in the foregoing prior art or utility model content or the following examples. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is cross section structure schematic diagram of short-circuit prevention positive pole piece of the utility model;

[0034] Figure: 1-positive current collector;2-positive coating;21-positive material center area;22-edge solid-state electrolyte protection area;3-surface solid-state electrolyte protection layer. DETAILED DESCRIPTION

[0035] The utility model will be further described in combination with examples, and it should be noted that the following examples are provided only for illustrative purposes and do not constitute a limitation on the scope of protection required by the utility model.

[0036] Example 1

[0037] (1) preparation of short-circuit prevention positive pole piece:

[0038] Add positive active material NMC811, sulfide electrolyte Li6PS5Cl, conductive agent VGCF and binder SEBS according to the weight ratio of 70:25:2.5:2.5;The binder is dissolved in dimethylbenzene to form SEBS glue solution;The glue solution is mixed and stirred with NMC811, Li6PS5Cl and VGCF for 2h to obtain a positive slurry, the slurry is coated on both sides of the carbon-coated aluminum foil, the size is 14cm×19.4cm, 55℃ drying to remove solvent, the coating is rolled to obtain a positive material center area;

[0039] The sulfide electrolyte Li6PS5Cl and the binder SEBS are added in a weight ratio of 98:2, the binder is dissolved in xylene to form a SEBS glue solution, the glue solution is mixed with Li6PS5Cl and stirred for 2 h to obtain an electrolyte slurry, the electrolyte slurry is coated on the edge of the positive electrode material central area, the total width of the two sides is 4 mm, and the thickness is the same as that of the positive electrode material central area after rolling; the electrolyte slurry is coated on the surface of the positive electrode material central area and the edge coating (edge solid-state electrolyte protection area) on both sides, the coating size is just enough to cover the surface of the positive electrode material central area and the edge coating, and the thickness is 30 μm; and the electrode piece is cut into a required size.

[0040] (2) Preparation of electrolyte layer and composite negative electrode piece:

[0041] The SiO / C material, the sulfide electrolyte Li6PS5Cl, the conductive agent VGCF, and the binder SEBS are added in a weight ratio of 70:24:3:3; the binder is dissolved in xylene to form a SEBS glue solution; the glue solution is mixed with the SiO / C material, Li6PS5Cl, and VGCF and stirred for 2 h to obtain a negative electrode slurry; the slurry is coated on both surfaces of the carbon-coated copper foil, the size is 14.4 cm x 19.8 cm, and the slurry is dried at 55°C to remove the solvent, thereby obtaining a negative electrode piece.

[0042] The sulfide electrolyte Li6PS5Cl and the binder SEBS are added in a weight ratio of 98:2, the binder is dissolved in xylene to form a SEBS glue solution; the glue solution is mixed with Li6PS5Cl and stirred for 2 h to obtain an electrolyte slurry, which is coated on an aluminum foil and transferred to the surface of the negative electrode on both sides by rolling, and the electrode piece is cut into a required size, thereby obtaining a composite negative electrode piece.

[0043] (3) Assembly and testing of the all-solid-state battery:

[0044] The short-circuit-preventing positive electrode piece and the composite negative electrode piece with the same size of 14.4 cm x 19.8 cm are aligned and stacked into one body to form a structure of an electrolyte layer, a negative electrode coating, a copper foil, a negative electrode coating, an electrolyte layer, a surface coating, a positive electrode coating, an aluminum foil, a positive electrode coating, a surface coating, an electrolyte layer, a negative electrode coating, a copper foil, a negative electrode coating, and an electrolyte layer, the positive and negative electrode tabs are welded, the aluminum plastic film is vacuum packaged, 4 min of isostatic pressing at 350 MPa is performed, and an all-solid-state battery cell is obtained, and the battery performance is tested at 40 MPa.

[0045] Example 2

[0046] (1) Preparation of a short-circuit-preventing positive electrode piece:

[0047] The positive active material lithium cobaltate LiCoO2, the oxide electrolyte Li7La3Zr2O 12Super P and binder PVDF; the binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution; the glue solution is mixed with LiCoO2, Li7La3Zr2O 12 Super P and binder PVDF to form an electrolyte slurry, which is coated on the edge of the positive material center area, with a total width of 3 mm on both sides and the same thickness as the positive material center area after rolling; the electrolyte slurry is coated on the surface of the positive material center area and the edge coating, with a coating size just covering the surface of the positive material center area and the edge coating, and a thickness of 20 μm; the electrode piece is cut to the required size.

[0048] The oxide electrolyte Li7La3Zr2O 12 and the binder PVDF are added in a weight ratio of 97:3; the binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution; the glue solution is mixed with Li7La3Zr2O 12 for 2 h to obtain an electrolyte slurry, which is coated on the edge of the positive material center area, with a total width of 3 mm on both sides and the same thickness as the positive material center area after rolling; the electrolyte slurry is coated on the surface of the positive material center area and the edge coating, with a coating size just covering the surface of the positive material center area and the edge coating, and a thickness of 20 μm; the electrode piece is cut to the required size.

[0049] (2) Preparation of electrolyte layer and composite negative electrode piece:

[0050] The artificial graphite negative electrode, sulfide electrolyte Li6PS5Cl, conductive agent Super P and binder PVDF are added in a weight ratio of 60:35:2:3; the binder is dissolved in dimethylbenzene to form a PVDF glue solution; the glue solution is mixed with artificial graphite, Li6PS5Cl and Super P for 2 h to obtain a negative electrode slurry, which is coated on both sides of a carbon-coated copper foil with a size of 12.3 cm x 16.3 cm; the solvent is removed by drying at 80°C to obtain a negative electrode piece.

[0051] The sulfide electrolyte Li6PS5Cl and the binder PVDF are added in a weight ratio of 96:4; the binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution; the glue solution is mixed with Li6PS5Cl for 2 h to obtain an electrolyte slurry, which is coated on an aluminum foil and transferred to the surface of the negative electrode by rolling, and the electrode piece is cut to the required size to obtain a composite negative electrode piece.

[0052] (3) Assembly and testing of all-solid-state battery:

[0053] The short-circuit prevention positive electrode sheet and the composite negative electrode sheet with the same size of 12.3 cm x 16.3 cm are aligned and stacked into one body to form a structure of electrolyte layer, negative electrode coating layer, copper foil, negative electrode coating layer, electrolyte layer, surface coating layer, positive electrode coating layer, aluminum foil, positive electrode coating layer, surface coating layer, electrolyte layer, negative electrode coating layer, copper foil, negative electrode coating layer, and electrolyte layer. The positive and negative electrode tabs are welded, the aluminum plastic film is vacuum packaged, and 300 MPa isostatic pressing is performed for 3 min to obtain a full solid-state battery cell. The battery performance is tested at 35 MPa.

[0054] Example 3

[0055] (1) Preparation of short-circuit prevention positive electrode sheet:

[0056] The positive electrode active material LiFeO4, the polymer electrolyte PEO, the conductive agent acetylene black, and the binder PVDF are added in a weight ratio of 85:10:2:3. The binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution. The glue solution is mixed with LiFeO4, PEO, and acetylene black for 2 h to obtain a positive electrode slurry. The slurry is coated on both sides of the carbon-coated aluminum foil with a size of 10 cm x 15 cm. The coating is dried at 80°C to remove the solvent, and then rolled to obtain a positive electrode material center zone.

[0057] The polymer electrolyte PEO and the binder PVDF are added in a weight ratio of 96:4. The binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution. The glue solution is mixed with PEO for 2 h to obtain an electrolyte slurry. The electrolyte slurry is coated on the edges of the positive electrode material center zone with a total width of 3 mm and a thickness equal to that of the rolled positive electrode material center zone. The electrolyte slurry is coated on the surface of the positive electrode material center zone and the edge coating layer with a size just covering the positive electrode material center zone and the edge coating layer surface, and a thickness of 25 μm. The sheet is cut to the desired size.

[0058] (2) Preparation of electrolyte layer and composite negative electrode sheet:

[0059] The silicon negative electrode, the sulfide electrolyte Li6PS5Cl, the conductive agent acetylene black, and the binder PVDF are added in a weight ratio of 75:20:2:3. The binder is dissolved in dimethylbenzene to form a PVDF glue solution. The glue solution is mixed with the negative electrode, the sulfide electrolyte, and the conductive agent for 2 h to obtain a negative electrode slurry. The slurry is coated on both sides of the carbon-coated copper foil with a size of 10.3 cm x 15.3 cm. The coating is dried at 80°C to remove the solvent to obtain a negative electrode sheet.

[0060] The sulfide electrolyte Li6PS5Cl and the binder PVDF are added in a weight ratio of 97:3, the binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution; the glue solution is mixed with Li6PS5Cl and stirred for 2 h to obtain an electrolyte slurry, which is coated on an aluminum foil and transferred to the surface of the negative electrode by rolling to form a composite negative electrode sheet.

[0061] (3) Assembly and testing of the all-solid-state battery:

[0062] The short-circuit-preventing positive electrode sheet and the composite negative electrode sheet with the same size of 10.3 cm x 15.3 cm are aligned and stacked into one body to form a structure of an electrolyte layer, a negative electrode coating layer, a copper foil, a negative electrode coating layer, an electrolyte layer, a surface coating layer, a positive electrode coating layer, an aluminum foil, a positive electrode coating layer, a surface coating layer, an electrolyte layer, a negative electrode coating layer, a copper foil, a negative electrode coating layer, and an electrolyte layer, the positive and negative electrode tabs are welded, the aluminum plastic film is vacuum packaged, and the isostatic pressing is performed at 320 MPa for 3.5 min to obtain an all-solid-state battery cell, and the battery performance is tested at 38 MPa.

[0063] Example 4

[0064] (1) Preparation of the short-circuit-preventing positive electrode sheet:

[0065] The positive electrode active material lithium manganate LiMn2O4, the halide electrolyte Li3InCl6, the conductive agent Super P, and the binder PTFE are added in a weight ratio of 60:35:2.5:2.5; the binder is dispersed in ethanol to form a PTFE glue solution; the glue solution is mixed with lithium manganate, Li3InCl6, and Super P and stirred for 2 h to obtain a positive electrode slurry, the slurry is coated on both surfaces of a carbon-coated aluminum foil with a size of 13 cm x 18 cm, the solvent is removed by drying at 60°C, and the coating layer is rolled to obtain a positive electrode material center zone.

[0066] The halide electrolyte Li3InCl6 and the binder PTFE are added in a weight ratio of 99:1, the binder is dispersed in ethanol to form a PTFE glue solution; the glue solution is mixed with Li3InCl6 and stirred for 2 h to obtain an electrolyte slurry, the electrolyte slurry is coated on the edges of the positive electrode material center zone with a total width of 3 mm and a thickness same as that of the positive electrode material center zone after rolling; the electrolyte slurry is coated on the surface of the positive electrode material center zone and the edge coating layer with a thickness of 35 μm, and the sheet is cut into the required size.

[0067] (2) Preparation of the electrolyte layer and the composite negative electrode sheet:

[0068] The tin negative electrode, sulfide electrolyte Li6PS5Cl, conductive agent Super P and binder PTFE are added in a weight ratio of 65:30:2:3; the binder is dissolved in xylene to form a PTFE glue solution; the glue solution is mixed and stirred with the negative electrode, sulfide electrolyte and conductive agent for 2 h to obtain a negative electrode slurry, the slurry is coated on both sides of the carbon-coated copper foil with a size of 13.3 cm x 18.3 cm, and the solvent is removed by drying at 60°C to obtain a negative electrode sheet.

[0069] The sulfide electrolyte Li6PS5Cl and the binder PTFE are added in a weight ratio of 98:2, the binder is dispersed in ethanol to form a PTFE glue solution; the glue solution is mixed and stirred with Li6PS5Cl for 2 h to obtain an electrolyte slurry, which is coated on an aluminum foil and transferred to the surface of the negative electrode by rolling to form a composite negative electrode sheet.

[0070] (3) Assembly and testing of all-solid-state battery:

[0071] The short-circuit-proof positive electrode sheet and the composite negative electrode sheet with the same size of 13.3 cm x 18.3 cm are aligned and stacked into one body to form a structure of electrolyte layer, negative electrode coating, copper foil, negative electrode coating, electrolyte layer, surface coating, positive electrode coating, aluminum foil, positive electrode coating, surface coating, electrolyte layer, negative electrode coating, copper foil, negative electrode coating, electrolyte layer, and the positive and negative electrode tabs are welded, the aluminum plastic film is vacuum packaged, and the isostatic pressing is performed at 380 MPa for 4.5 min to obtain an all-solid-state battery cell, and the battery performance is tested at 42 MPa.

[0072] Example 5

[0073] (1) Preparation of short-circuit-proof positive electrode sheet:

[0074] The positive electrode active material LiNi0.5Mn1.5O4, oxide electrolyte LiAlTi(PO4)3, conductive agent graphene and binder PAA are added in a weight ratio of 75:20:2.5:2.5; the binder is dissolved in water to form a PAA glue solution; the glue solution is mixed and stirred with LiNi0.5Mn1.5O4, LiAlTi(PO4)3 and graphene for 2 h to obtain a positive electrode slurry, which is coated on both sides of a carbon-coated aluminum foil with a size of 11 cm x 16 cm, and the solvent is removed by drying at 70°C, and the coating is rolled to obtain a positive electrode material center zone. 0.5 Mn 1.5 O4, oxide electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3, conductive agent graphene and binder PAA; the binder is dissolved in water to form a PAA glue solution; the glue solution is mixed and stirred with LiNi0.5Mn1.5O4, LiAlTi(PO4)3 and graphene for 2 h to obtain a positive electrode slurry, which is coated on both sides of a carbon-coated aluminum foil with a size of 11 cm x 16 cm, and the solvent is removed by drying at 70°C, and the coating is rolled to obtain a positive electrode material center zone. 0.5 Mn 1.5 O4, oxide electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3 and graphene for 2 h to obtain a positive electrode slurry, which is coated on both sides of a carbon-coated aluminum foil with a size of 11 cm x 16 cm, and the solvent is removed by drying at 70°C, and the coating is rolled to obtain a positive electrode material center zone.

[0075] Solid-state electrolyte Li was added in a weight ratio of 98.5:1.5 1.3 Al 0.3 Ti 1.7 (PO4)3and binder PAA, the binder was dissolved in water to form a PAA glue solution; the glue solution was mixed with the solid-state electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3for 2h to obtain an electrolyte slurry, the electrolyte slurry was coated on the edge of the positive electrode material central region, with a total width of 3mm on both sides, and a thickness the same as that of the positive electrode material central region after rolling; the electrolyte slurry was coated on the surface of the positive electrode material central region and the edge coating layer, with a size just covering the positive electrode material central region and the surface of the edge coating layer, and a thickness of 30μm; the electrode piece was cut into the required size.

[0076] (2) Preparation of electrolyte layer and composite negative electrode piece:

[0077] SiO / C negative electrode, sulfide electrolyte Li6PS5Cl, conductive agent graphene and binder PAA were added in a weight ratio of 70:25:2:3; the binder was dissolved in xylene to form a PAA glue solution; the glue solution was mixed with the negative electrode, the sulfide electrolyte and the conductive agent for 2h to obtain a negative electrode slurry, which was coated on both surfaces of the carbon-coated copper foil with a size of 11.3cm×16.3cm, and dried at 70℃ to remove the solvent, thereby obtaining a negative electrode piece.

[0078] Sulfide electrolyte Li6PS5Cl and binder PAA were added in a weight ratio of 97:3, the binder was dissolved in xylene to form a PAA glue solution; the glue solution was mixed with Li6PS5Cl for 2h to obtain an electrolyte slurry, which was coated on an aluminum foil and transferred to the surface of the negative electrode by rolling, and the electrode piece was cut into the required size, thereby obtaining a composite negative electrode piece.

[0079] (3) Assembly and testing of all-solid-state battery:

[0080] The short-circuit prevention positive electrode piece and the composite negative electrode piece with the same size of 11.3cm×16.3cm were aligned and stacked into one body to form a structure of electrolyte layer, negative electrode coating layer, copper foil, negative electrode coating layer, electrolyte layer, surface coating layer, positive electrode coating layer, aluminum foil, positive electrode coating layer, surface coating layer, electrolyte layer, negative electrode coating layer, copper foil, negative electrode coating layer, electrolyte layer, and the positive and negative electrode tabs were welded, the aluminum plastic film was vacuum packaged, and the isostatic pressing was performed at 360MPa for 4min, thereby obtaining an all-solid-state battery cell, and the battery performance was tested at 40MPa.

[0081] Comparative Example 1

[0082] The steps for preparing the positive electrode piece were the same as those in Example 1, but no edge solid-state electrolyte protection zone and surface solid-state electrolyte protection layer were provided.

[0083] (1) Preparation of positive electrode sheet:

[0084] Add positive active material NMC811, sulfide electrolyte Li6PS5Cl, conductive agent VGCF and binder SEBS according to the weight ratio of 70:25:2.5:2.5; dissolve the binder in dimethylbenzene to form SEBS glue solution; mix and stir the glue solution with NMC811, Li6PS5Cl and VGCF for 2h to obtain positive electrode slurry; coat the slurry on both sides of the carbon-coated aluminum foil with a size of 14cmx19.4cm; dry at 55℃ to remove the solvent; roll the coating to obtain a positive electrode coating; and cut the electrode sheet into the required size.

[0085] (2) Preparation of electrolyte layer and composite negative electrode sheet is the same as in Example 1.

[0086] (3) Assembly and testing of the all-solid-state battery is similar to Example 1.

[0087] Comparative Example 2

[0088] When preparing the positive electrode sheet, the width of the edge protection zone is 0.2mm, and the other steps are the same as in Example 1.

[0089] (1) Preparation of short-circuit-proof positive electrode sheet:

[0090] Add positive active material NMC811, sulfide electrolyte Li6PS5Cl, conductive agent VGCF and binder SEBS according to the weight ratio of 70:25:2.5:2.5; dissolve the binder in dimethylbenzene to form SEBS glue solution; mix and stir the glue solution with NMC811, Li6PS5Cl and VGCF for 2h to obtain positive electrode slurry; coat the slurry on both sides of the carbon-coated aluminum foil with a size of 14cmx19.4cm; dry at 55℃ to remove the solvent; roll the coating to obtain a positive electrode material center zone;

[0091] Add sulfide electrolyte Li6PS5Cl and binder SEBS according to the weight ratio of 98:2; dissolve the binder in dimethylbenzene to form SEBS glue solution; mix and stir the glue solution with Li6PS5Cl for 2h to obtain electrolyte slurry; coat the electrolyte slurry on the edges of the positive electrode material center zone with a total width of 0.2mm on both sides and a thickness equal to that of the positive electrode material center zone after rolling; coat the electrolyte slurry on both sides of the positive electrode material center zone and the edge coating surface with a thickness of 30μm; and cut the electrode sheet into the required size.

[0092] (2) Preparation of electrolyte layer and composite negative electrode sheet is the same as in Example 1.

[0093] (3) The assembly and test of the all-solid-state battery are similar to those of Example 1.

[0094] Comparative Example 3

[0095] The steps of preparing the positive electrode tab are the same as those of Example 3, but no surface solid-state electrolyte protective layer is provided.

[0096] (1) Preparation of the short-circuit-proof positive electrode tab:

[0097] The positive electrode active material LiFeO4, the polymer electrolyte PEO, the conductive agent acetylene black and the binder PVDF are added in a weight ratio of 85:10:2:3; the binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution; the glue solution is mixed with LiFeO4, PEO and acetylene black for 2 h to obtain a positive electrode slurry, the slurry is coated on both sides of a carbon-coated aluminum foil with a size of 10 cm x 15 cm, and the coating is dried at 80°C to remove the solvent, and then the coating is rolled to obtain a positive electrode material center zone.

[0098] The polymer electrolyte PEO and the binder PVDF are added in a weight ratio of 96:4, the binder is dissolved in N-methyl pyrrolidone to form a PVDF glue solution; the glue solution is mixed with PEO for 2 h to obtain an electrolyte slurry, and the electrolyte slurry is coated on the edges of the positive electrode material center zone with a total width of 3 mm on both sides, and the thickness is the same as that of the positive electrode material center zone after rolling, and the tab is cut into the required size.

[0099] (2) The preparation of the electrolyte layer and the composite negative electrode tab is the same as that of Example 3.

[0100] (3) The assembly and test of the all-solid-state battery are similar to those of Example 3.

[0101] Comparative Example 4

[0102] When preparing the positive electrode tab, the thickness of the edge protective layer is 5 μm less than that of the positive electrode material center zone, and the other steps are the same as those of Example 4.

[0103] (1) Preparation of the short-circuit-proof positive electrode tab:

[0104] The positive electrode active material lithium manganate LiMn2O4, the halide electrolyte Li3InCl6, the conductive agent Super P and the binder PTFE are added in a weight ratio of 60:35:2.5:2.5; the binder is dispersed in ethanol to form a PTFE glue solution; the glue solution is mixed with lithium manganate LiMn2O4, Li3InCl6 and Super P for 2 h to obtain a positive electrode slurry, and the slurry is coated on both sides of a carbon-coated aluminum foil with a size of 13 cm x 18 cm, and the coating is dried at 60°C to remove the solvent, and then the coating is rolled to obtain a positive electrode material center zone.

[0105] The halide electrolyte Li3InCl6 and the binder PTFE are added in a weight ratio of 99:1, the binder is dispersed in ethanol to form a PTFE glue solution; the glue solution is mixed with Li3InCl6 and stirred for 2h to obtain an electrolyte slurry, the electrolyte slurry is coated on the edge of the center area of the positive electrode material, and the total width of the two sides is 3mm, and the thickness is 5um less than that of the center area of the positive electrode material; the electrolyte slurry is coated on the surface of the center area and the edge coating of the positive electrode material, and the coating size is just enough to cover the surface of the center area and the edge coating of the positive electrode material, and the thickness is 35um; and the electrode piece is cut into a required size.

[0106] (2) The preparation of the electrolyte layer and the composite negative electrode piece is the same as that in Example 4.

[0107] (3) The assembly and test of the full solid-state battery are similar to those in Example 4.

[0108] Test method:

[0109] The battery is subjected to charge-discharge test under the condition of 40-80℃ environment, and the pressure applied is 35MPa to 42MPa, the charge-discharge rate is 0.1C, and the voltage range is 2.5-4.3V.

[0110] The test results are shown in Table 1.

[0111] Table 1

[0112]

[0113] Through the battery performance test of the examples and the comparative examples, the results show that the full solid-state battery containing the short-circuit prevention positive electrode piece in the examples is obviously superior to the comparative examples in terms of discharge specific capacity, initial efficiency and starting voltage.

[0114] The above examples are only used to illustrate the technical solutions of the utility model, and not to limit them. Although the utility model has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified or some or all of the technical features can be replaced equivalently without departing from the spirit and essence defined in the claims of the utility model; and these modifications or replacements are still within the scope defined in the claims of the utility model.

Claims

1. A positive electrode sheet capable of preventing short circuit, characterized by comprising: The short-circuit prevention positive electrode sheet comprises a positive electrode current collector, both sides of the positive electrode current collector are sequentially provided with a positive electrode coating and a surface solid-state electrolyte protection layer, the positive electrode coating comprises a positive electrode material central region and an edge solid-state electrolyte protection region, the edge solid-state electrolyte protection region surrounds the positive electrode material central region, and the surface solid-state electrolyte protection layer completely covers the positive electrode material central region and the edge solid-state electrolyte protection region.

2. The short circuit prevention positive electrode plate of claim 1, wherein, The thickness of the edge solid-state electrolyte protection region is 1-300 μm, and the width of the edge solid-state electrolyte protection region is 0.5-5 mm.

3. The short circuit prevention positive electrode plate of claim 1, wherein, The thickness of the surface solid-state electrolyte protection layer is 1-100 μm.

4. An all-solid battery, characterized by, The short-circuit prevention positive electrode sheet comprises a positive electrode current collector, both sides of the positive electrode current collector are sequentially provided with a positive electrode coating and a surface solid-state electrolyte protection layer, the positive electrode coating comprises a positive electrode material central region and an edge solid-state electrolyte protection region, the edge solid-state electrolyte protection region surrounds the positive electrode material central region, and the surface solid-state electrolyte protection layer completely covers the positive electrode material central region and the edge solid-state electrolyte protection region. The thickness of the edge solid-state electrolyte protection region is 1-300 μm, and the width of the edge solid-state electrolyte protection region is 0.5-5 mm. The thickness of the surface solid-state electrolyte protection layer is 1-100 μm. The short-circuit prevention positive electrode sheet comprises a positive electrode current collector, both sides of the positive electrode current collector are sequentially provided with a positive electrode coating and a surface solid-state electrolyte protection layer, the positive electrode coating comprises a positive electrode material central region and an edge solid-state electrolyte protection region, the edge solid-state electrolyte protection region surrounds the positive electrode material central region, and the surface solid-state electrolyte protection layer completely covers the positive electrode material central region and the edge solid-state electrolyte protection region. The thickness of the edge solid-state electrolyte protection region is 1-300 μm, and the width of the edge solid-state electrolyte protection region is 0.5-5 mm. The thickness of the surface solid-state electrolyte protection layer is 1-100 μm.

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