An all-solid-state battery and a method for manufacturing the same

Abstract

This invention provides an all-solid-state battery and its preparation method, belonging to the field of all-solid-state battery technology. The all-solid-state battery includes a solid electrolyte layer and alternately stacked positive and negative electrodes, with the solid electrolyte layer positioned between the positive and negative electrodes. An insulating layer is disposed on the positive electrode current collector surrounding the positive electrode material region on the side where the tab is located and on the opposite side. Insulating tape is applied to the top and bottom of both sides of the positive electrode without an insulating layer. By providing an adhesive-coated ion / electron insulating layer around the tab and the opposite side of the positive electrode material region, and by applying insulating tape to the top and bottom surfaces of both sides of the positive electrode without an insulating layer, this invention effectively prevents short circuits caused by shearing at the edges of the positive and negative electrode plates under high voltage, improving the safety and reliability of the battery.

Description

Technical Field

[0001] This invention belongs to the field of all-solid-state battery technology, specifically relating to an all-solid-state battery and its preparation method. Background Technology

[0002] With the continuous growth of energy demand and the increasing severity of environmental problems, the development of new energy vehicles has become a global focus. All-solid-state batteries, as a new type of battery with high energy density, long cycle life, and high safety, are considered the ideal power source for future electric vehicles.

[0003] However, the development of all-solid-state batteries still faces some challenges. One of them is that the shearing of the positive and negative electrode edges under high voltage may cause short circuits in the battery, thus affecting the battery's performance and reliability.

[0004] In an all-solid-state battery structure, a solid electrolyte layer is placed between the positive and negative electrodes. Due to the size difference between the positive electrode, negative electrode, and electrolyte film ("negative electrode wrapping positive electrode" structure, i.e., the area of ​​the negative electrode is larger than that of the positive electrode, and the positive electrode is narrower than the negative electrode after being stacked), the edges of the positive electrode will exert shear force on the electrolyte layer during isostatic pressing or flat plate pressing after stacking. This can easily cause the edges of the positive electrode to puncture the electrolyte layer and come into contact with the negative electrode, causing a short circuit in the battery, thus affecting the battery's performance and reliability. Moreover, as the number of layers increases, in order to better reduce the cell impedance at multiple interfaces, the pressure and time of pressurization will be appropriately increased, which makes it easier to cause indentations and damage to the electrolyte layer and negative electrode.

[0005] Therefore, developing a simple and effective short-circuit-resistant all-solid-state battery structure and its fabrication method is of great practical significance. Summary of the Invention

[0006] To address at least one of the problems in the prior art, this invention provides an all-solid-state battery. By setting an ion / electron insulating region around the positive electrode active region on the side where the positive electrode tab is located and on the opposite side, and attaching insulating tape to the upper and lower surfaces of the positive electrode on both sides without insulating regions, the battery can be effectively prevented from short-circuiting, thereby improving the battery yield and safety.

[0007] One of the objectives of this invention is to provide an all-solid-state battery.

[0008] The second objective of this invention is to provide a method for preparing the all-solid-state battery.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] In a first aspect, the present invention provides an all-solid-state battery, comprising a solid electrolyte layer and alternatingly stacked positive and negative electrode plates, wherein the solid electrolyte layer is located between the positive and negative electrode plates, and the solid electrolyte layer and the negative electrode plates are of equal size;

[0011] The positive electrode sheet includes a positive current collector and a coating layer on both sides of the positive current collector. The coating layer includes a positive electrode material region and an insulating material region on both sides of the positive electrode material region. The two opposite sides are the side where the tab is located and the side opposite to it. Along the direction perpendicular to the side where the tab is located and the side opposite to it, the size of the positive electrode sheet (positive electrode material region and insulating material region) is larger than the size of the solid electrolyte layer. Along the direction where the tab is located and the side opposite to it, the size of the positive electrode sheet (positive electrode material region) is greater than or equal to the size of the solid electrolyte layer.

[0012] Insulating tape is pasted on the upper and lower surfaces of the positive electrode sheet along the side where the vertical tab is located and the opposite side. The insulating tape covers all or part of the edge of the positive electrode sheet in the width direction. After the sheets are stacked and pressed, the insulating tape is pressed into the adjacent solid electrolyte layer in all or part.

[0013] The structure of solid electrolytes will be described in detail below:

[0014] A schematic diagram of the cross-sectional structure of the insulating tape along the length of the pressure front edge during the assembly of the all-solid-state battery stack of this invention is shown below. Figure 1 As shown, a schematic diagram of the cross-sectional structure along the length of the insulating material region is as follows. Figure 2 As shown in the diagram, the surface structure of the positive electrode is as follows: Figure 3 As shown.

[0015] The all-solid-state battery includes a solid electrolyte layer 3 and alternating stacked positive electrode 1 and negative electrode 2, with the solid electrolyte layer 3 located between the positive electrode 1 and the negative electrode 2.

[0016] The positive electrode 1 includes a positive current collector 11. Coating layers (positive electrode material region 12 and insulating material region 13) are provided on both the front and back surfaces of the positive current collector 11. The insulating material region 13 is located on the side where the tab is located and on the opposite side of the positive electrode material region 12, i.e., two elongated regions. The solid electrolyte layer 3 has the same size as the negative electrode 2. Along the direction perpendicular to the side where the tab is located and on the opposite side, the length L1 of the coating layer (the length L2 of the positive electrode material region 12 in this direction + the width of two insulating material regions 13) is greater than the length of the solid electrolyte layer 3 in this direction. Along the side where the tab is located and on the opposite side, the length L3 of the coating layer (the length of the positive electrode material region 12 in this direction = the length of the insulating material region 13) is greater than or equal to the length of the solid electrolyte layer 3 in this direction.

[0017] After forming the positive electrode sheet, insulating tapes 4 are pasted on the upper and lower surfaces on both sides of the non-insulating material area of the positive electrode sheet. In the direction along the side where the tab is located and its opposite side (i.e., the width direction of the insulating tape), the insulating tape 4 partially (or completely) covers the edge of the positive electrode sheet, that is, L4 < L3, L5 ≥ L3. L2 ≤ the length of the insulating tape 4 ≤ L1( Figure 3 In Figure 3 , it is the case where the length of the insulating tape is equal to L1).

[0018] The schematic cross-sectional structure diagram along the direction of the insulating tape after being pressed is as shown in Figure 4 shown, and the schematic cross-sectional structure diagram along the direction of the insulating material area is as shown in Figure 5 shown. With the overall structure being further compressed along the insulating material area, the insulating tape will also be pressed into the adjacent solid electrolyte layer (only a little indentation).

[0019] Insulating material area:

[0020] The material of the insulating material area of the present invention is at least one of PVDF and its modified materials, PAN and its modified materials, PI and its modified materials, natural rubber NR, styrene-butadiene rubber SBR, butyl rubber IIR, hydrogenated nitrile rubber HNBR, ethylene-propylene rubber EPDM, nitrile rubber NBR, chloroprene rubber CR, silicone rubber, polyurethane, styrene-butadiene block copolymer rubber SBS and its modified material SEBS, polyisobutylene rubber PIB, or a mixture thereof with inorganic fillers.

[0021] In some embodiments, when not under force, the thickness L of the insulating material area and the thickness M of the positive electrode material area satisfy the following relationship: L - 50 μm ≤ M ≤ L + 30 μm, and the units of L and M are μm.

[0022] When not under force, the thickness of the insulating material area can be slightly larger, slightly smaller, or equal to the thickness of the positive electrode material area. When the thickness of the insulating material area is slightly larger or equal to the thickness of the positive electrode material area (i.e., L ≥ M, L - M ≤ 50 μm), both the insulating material area and the positive electrode material area are compressed under pressure, but the thickness of the insulating material area cannot be much higher than the thickness of the positive electrode material area. This is because if it is higher than 50 μm, during the rolling of the positive electrode layer / or the isostatic pressing of the battery cell, it will cause poor contact between the positive electrode layer and the electrolyte layer, and even cause the positive electrode layer to break, thus affecting the battery performance; when the thickness of the insulating material area is slightly smaller than the thickness of the positive electrode material area (i.e., L < M, M - L ≤ 30 μm), the positive electrode material area will also be slightly compressed under pressure. To ensure that it can be pressed to the insulating material area, the thickness of the insulating material area cannot be much lower than the thickness of the positive electrode material area.

[0023] This design can avoid the shearing effect of the positive electrode active material area on the electrolyte layer, also avoid the fracture of the negative electrode sheet during the pressure treatment of the battery cell due to the thickness difference, and at the same time will not have too much impact on the energy density of the battery.

[0024] In some implementations, the width of the insulating material area = (L1-L2) / 2 is 0.5 to 10 mm.

[0025] Insulating tape:

[0026] The insulating tape of the present invention is made of at least one of PI, PE, PP, PET, and PEEK.

[0027] In some implementations, the thickness of the insulating tape is 1–20 μm;

[0028] In some embodiments, the width of the insulating tape = (L5-L4) / 2 is 0.5 to 10 mm, and preferably the insulating tape completely covers the edge of the positive electrode sheet.

[0029] The length and width of the positive current collector and the positive material region of the positive electrode sheet are both less than 2000 mm.

[0030] In some embodiments, the positive current collector is aluminum foil; the positive electrode material region comprises the following components by mass percentage: 70-94% positive electrode active material, 1-3% conductive agent, 1-3% binder, and 4-28% sulfide electrolyte.

[0031] In some embodiments, the positive electrode active material is at least one selected from ternary materials, lithium iron phosphate, lithium cobalt oxide, lithium manganese iron phosphate, lithium-rich manganese-based materials, and sulfur positive electrode materials (such as composites of sulfur and carbon, or composites of sulfur and organic matter).

[0032] In some embodiments, the conductive agent is at least one selected from acetylene black, Super P, Super S, 350G, carbon fiber VGCF, carbon nanotubes CNTs, Ketjen black, graphite conductive agents (such as KS-6, KS-15, SFG-6, SFG-15) and graphene.

[0033] In some embodiments, the binder is at least one selected from polyvinylidene fluoride (PVDF) and its modified forms, polytetrafluoroethylene (PTFE) and its modified forms, polyethylene oxide (PEO), polypropylene carbonate (PPC), polyvinyl carbonate (PEC), polytrimethylene carbonate (PTMC), polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), polyolefins (polyethylene, polypropylene and their copolymers), hydrogenated styrene-butadiene block copolymer (SEBS), cyano rubber (NBR), modified SBR, fluorinated rubber, and polyurethane.

[0034] In some embodiments, the sulfide electrolyte is at least one selected from binary sulfide electrolytes, ternary sulfide electrolytes, and sulfide-germanium sulfide electrolytes, preferably lithium phosphorus sulfur chloride (Li6PS5Cl).

[0035] The thickness of the positive electrode can be 30–450 μm.

[0036] Negative electrode plate:

[0037] The negative electrode sheet includes a negative electrode current collector and negative electrode material layers on both sides. The negative electrode material layers include the following components by mass percentage: 60-90% negative electrode active material, 1-3% conductive agent, 1-3% binder, and 4-38% sulfide electrolyte.

[0038] In some implementations, the negative current collector is copper foil;

[0039] In some embodiments, the negative electrode active material is selected from at least one of carbon materials (such as conductive carbon black, carbon nanotubes, graphene, fullerene, carbon nanofibers), silicon negative electrode materials (such as silicon suboxide, nano-silicon), tin negative electrode materials (such as tin-carbon negative electrode materials), lithium metal negative electrode materials, and lithium-free negative electrode materials (such as silver-carbon negative electrode materials).

[0040] In some embodiments, the conductive agent is at least one selected from acetylene black, Super P, Super S, 350G, carbon fiber VGCF, carbon nanotubes CNTs, Ketjen black, graphite conductive agents (such as KS-6, KS-15, SFG-6, SFG-15) and graphene.

[0041] In some embodiments, the binder is at least one selected from polyvinylidene fluoride (PVDF) and its modified forms, polytetrafluoroethylene (PTFE) and its modified forms, polyethylene oxide (PEO), polypropylene carbonate (PPC), polyvinyl carbonate (PEC), polytrimethylene carbonate (PTMC), polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), polyolefins (polyethylene, polypropylene and their copolymers), hydrogenated styrene-butadiene block copolymer (SEBS), cyano rubber (NBR), modified SBR, fluorinated rubber, and polyurethane.

[0042] In some embodiments, the sulfide electrolyte is at least one selected from binary sulfide electrolytes, ternary sulfide electrolytes, and sulfide-germanium sulfide electrolytes, preferably lithium phosphorus sulfur chloride (Li6PS5Cl).

[0043] The thickness of the negative electrode can be 20–400 μm.

[0044] Solid electrolyte layer:

[0045] The solid electrolyte layer comprises the following components by mass percentage: 95–99.5% solid electrolyte and 0.5–5% binder.

[0046] In some embodiments, the solid electrolyte is at least one selected from sulfide electrolytes, oxide electrolytes, chloride electrolytes, and polymer electrolytes; preferably, it is a sulfide-germanium ore type solid electrolyte (Li6PS5X, X = Cl, Br, I), for example, lithium phosphorus-sulfur-chloride (Li6PS5Cl).

[0047] In some embodiments, the binder is at least one selected from polyvinylidene fluoride (PVDF) and its modified forms, polytetrafluoroethylene (PTFE) and its modified forms, polyethylene oxide (PEO), polypropylene carbonate (PPC), polyvinyl carbonate (PEC), polytrimethylene carbonate (PTMC), polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), polyolefins (polyethylene, polypropylene and their copolymers), hydrogenated styrene-butadiene block copolymer (SEBS), cyano rubber (NBR), modified SBR, fluorinated rubber, and polyurethane.

[0048] The thickness of the solid electrolyte layer can be 5–200 μm.

[0049] Secondly, the present invention provides a method for preparing the above-mentioned all-solid-state battery, comprising the following steps:

[0050] (a) Prepare a solid electrolyte layer by coating a negative electrode material slurry on both sides of the negative electrode current collector and drying it to obtain a negative electrode sheet with a negative electrode material layer on both sides. Cut the solid electrolyte layer to make the size of the solid electrolyte layer equal to the size of the negative electrode sheet.

[0051] (b) First, a positive electrode material slurry is coated on both sides of the positive electrode current collector. After drying, a positive electrode material region is formed. Then, an insulating material slurry is coated around the positive electrode material region located on the side where the tab is located and on the opposite side. After drying, an insulating material region is formed (or a positive electrode material slurry is coated in the middle and an insulating material slurry is coated on the edge at the same time. After drying, a positive electrode sheet containing a positive electrode material region and an insulating material region is formed). The coating layer (positive electrode material region and insulating material region) along the direction perpendicular to the side where the tab is located and on the opposite side is cut so that the size of the coating layer (positive electrode material region) along the direction where the tab is located and on the opposite side is cut is larger than the size of the solid electrolyte layer. The size of the coating layer (positive electrode material region) along the direction where the tab is located and on the opposite side is cut is greater than or equal to the size of the solid electrolyte layer, thus obtaining a positive electrode sheet. Insulating tape is pasted on the upper and lower sides of the positive electrode sheet along both sides perpendicular to the side where the tab is located and on the opposite side, so that the width of the insulating tape covers all or part of the edge of the positive electrode sheet, thus obtaining a composite positive electrode sheet.

[0052] (c) Stack the negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer and negative electrode in sequence to obtain the battery cell; and apply pressure to the battery cell.

[0053] The pressurization method includes one of isostatic pressing, flat plate pressing, or roller pressing. The pressurization temperature is 0–1000℃, the pressurization time is 0.5–30 minutes, and the pressurization pressure is between 3–1000 MPa. Through pressurization, the contact between various battery components can be made tighter, improving the battery's conductivity and stability.

[0054] Beneficial effects:

[0055] This invention forms a positive electrode by coating an ion / electron insulating layer with adhesive on the tab of the positive electrode material area and its opposite periphery, and attaches insulating tape to the upper and lower surfaces of the other two sides of the positive electrode without an insulating layer. This effectively prevents short circuits caused by shearing at the edges of the positive and negative electrode plates under high voltage, thereby improving the safety and reliability of the battery.

[0056] Improved yield: Reduced short circuits, thereby increasing battery yield and reducing production costs.

[0057] Stable performance: By selecting and specifying the materials and dimensions of the insulation layer and tape, stable performance can be ensured during battery charging and discharging, thereby improving the battery's cycle life.

[0058] Simple and easy to implement: The preparation method of the present invention is simple, easy to operate, and suitable for large-scale production.

[0059] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the cell cross-section structure in the direction of the insulating tape at the front of the pressure-bearing edge during the stacking assembly of the all-solid-state battery of the present invention;

[0061] Figure 2 This is a schematic diagram of the cell cross-section structure in the direction of the insulating material region at the pressure front edge of the all-solid-state battery stack assembly according to the present invention;

[0062] Figure 3 This is a schematic diagram of the surface structure of the positive electrode.

[0063] Figure 4 This is a schematic diagram of the cross-sectional structure of the battery cell along the direction of the insulating tape after being compressed during the stacking assembly of the all-solid-state battery of the present invention.

[0064] Figure 5 This is a schematic diagram of the cross-sectional structure of the cell along the direction of the insulating material region after the all-solid-state battery stack assembly of the present invention is subjected to pressure;

[0065] Diagram: 1-Positive electrode sheet; 11-Positive current collector; 12-Positive electrode material region; 13-Insulating material region; 2-Negative electrode sheet; 3-Solid electrolyte layer; 4-Insulating tape. Detailed Implementation

[0066] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0067] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0068] Example 1

[0069] The specific steps for preparing an all-solid-state battery are as follows:

[0070] (1) Preparation of the negative electrode: The silicon negative electrode material (silicon suboxide, SiO2) is prepared. x Type 1300, Li6PS5Cl (31% dry powder), SEBS binder (2% dry powder), and VGCF conductive agent (2% dry powder) are dispersed in xylene solvent and thoroughly stirred to form a uniform and stable negative electrode material slurry. This slurry is then coated on both sides of a copper foil with a coating amount of 4.25 mg / cm². 2 After drying and rolling, a negative electrode with a thickness of 77μm is obtained; the size of the negative electrode after cutting is 100×100mm. 2 ;

[0071] (2) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared from oxide solid electrolyte (LATP) and polytetrafluoroethylene (PTFE) using a conventional solvent-free dry process. The solid electrolyte layer contained 98.5% oxide solid electrolyte and 1.5% PTFE; its thickness was 50 μm, and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0072] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene solvent, and 811 ternary material (80% by mass of dry powder), VGCF (2% by mass of dry powder) and Li6PS5Cl (16% by mass of dry powder) were added and stirred thoroughly to form a stable cathode material slurry; aluminum foil with a size of 120×120mm was provided. 2 A positive electrode material slurry is coated on both sides of an aluminum foil. The coating size is 100×98mm. 2 (i.e., length 100mm, width 98mm), surface density 22mg / cm³ 2After coating, drying, and rolling, the thickness is 150μm, forming the positive electrode material region. SBS slurry (SBS powder and ceramic dispersed in xylene solvent at a mass ratio of 9:1, with a solid content of 50%) is coated on both sides of the outer periphery of the electrode tab and the opposite side of the positive electrode material region (i.e., both sides at 98mm). The coating thickness is 160μm, and the width is 2mm. After drying, it is cut into 100×102mm pieces. 2 For the positive electrode sheet, apply insulating tape of PI material, 10μm thick, 5mm wide and 98mm long, to the upper and lower surfaces of both sides of the positive electrode sheet that are not coated with SBS paste, so as to completely cover the edge of the positive electrode sheet.

[0073] (4) Stack the negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, and negative electrode in that order, weld the tabs, and vacuum seal to prepare an all-solid-state battery cell. The battery cell has 10 positive electrode layers, 11 negative electrode layers, and a capacity of 6Ah. The battery cell is subjected to isostatic pressing at 150℃ for 15 minutes.

[0074] Example 2

[0075] The specific steps for preparing an all-solid-state battery are as follows:

[0076] (1) Preparation of negative electrode: Lithium metal is laminated onto both sides of copper foil to form a copper-lithium composite strip. The copper foil is 10 μm thick, and the lithium layer on both sides is 15 μm thick. The negative electrode size after cutting is 100 × 100 mm. 2 ;

[0077] (2) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a conventional solvent-free dry process using a sulfide solid electrolyte (Li6PS5Cl) and polytetrafluoroethylene (PTFE). The solid electrolyte layer contained 99.5% solid electrolyte and 0.5% PTFE; its thickness was 80 μm; and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0078] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) is completely dissolved in xylene solvent, and lithium-rich cathode material (80% by mass of dry powder), VGCF (2% by mass of dry powder) and Li6PS5Cl (16% by mass of dry powder) are added and stirred thoroughly to form a stable cathode material slurry; aluminum foil with a size of 120×120mm is provided. 2 A positive electrode material slurry is coated on both sides of an aluminum foil. The coating size is 104×98mm. 2 Coating surface density: 19.5 mg / cm³ 2A 100μm thick layer is formed to create the positive electrode material region. SEBS slurry (SEBS powder and ceramic dispersed in xylene solvent at a mass ratio of 4:1, with a solid content of 40%) is coated around the tab and the outer periphery of the positive electrode material region on the opposite side. The coating thickness is 110μm, and the width is 2mm. After drying, it is cut into 104×102mm pieces. 2 For the positive electrode sheet, apply insulating tape of PI material, 10μm thick, 5mm wide and 102mm long, to the upper and lower surfaces of both sides of the positive electrode sheet that are not coated with SEBS paste, so as to completely cover the edge of the positive electrode sheet.

[0079] (4) Stack the negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, and negative electrode in that order, weld the tabs, and vacuum seal to prepare an all-solid-state battery cell. The battery cell has 10 positive electrode layers, 11 negative electrode layers, and a capacity of 6Ah. The battery cell is then subjected to hot pressing treatment at 80℃ for 10 minutes.

[0080] Example 3

[0081] The specific steps for preparing an all-solid-state battery are as follows:

[0082] (1) Preparation of the negative electrode: Tin nanomaterials (65% by mass of dry powder), Li6PS5Cl (31% by mass of dry powder), SEBS binder (2% by mass of dry powder), and VGCF conductive agent (2% by mass of dry powder) were dispersed in xylene and stirred thoroughly to form a uniform and stable negative electrode material slurry. This slurry was then coated on both sides of a copper foil with a coating amount of 6.1 mg / cm². 2 After drying and rolling, a negative electrode with a thickness of 108μm is obtained; the size of the negative electrode after cutting is 100×100mm. 2 ;

[0083] (2) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a conventional solvent-free dry process using a chloride solid electrolyte (Li3InCl6) and polytetrafluoroethylene (molecular weight 5 million, KELU). The solid electrolyte layer contained 96.5% solid electrolyte and 3.5% polytetrafluoroethylene; its thickness was 10 μm, and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0084] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) is completely dissolved in xylene solvent, and lithium iron phosphate cathode material (80% by mass of dry powder), VGCF (2% by mass of dry powder) and Li6PS5Cl (16% by mass of dry powder) are added and stirred thoroughly to form a stable cathode material slurry; aluminum foil with a size of 120×120mm is provided. 2 A positive electrode material slurry is coated on both sides of an aluminum foil. The coating size is 101×98mm. 2Coating surface density 28 mg / cm³ 2 The cathode material region is formed with a thickness of 230 μm. EPDM slurry (EPDM powder and ceramic dispersed in xylene solvent at a mass ratio of 3:1, with a solid content of 40%) is coated around the tab and the cathode material region on the opposite side. The coating thickness is 210 μm and the width is 3 mm. After drying, it is cut into 101 × 104 mm pieces. 2 For the positive electrode sheet, apply insulating tape of PET material with a thickness of 5μm, a width of 2mm, and a length of 103mm to the upper and lower surfaces of both sides of the positive electrode sheet that are not coated with EPDM paste, so as to completely cover the edge of the positive electrode sheet.

[0085] (4) Stack the negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, and negative electrode in that order, weld the tabs, and vacuum seal to prepare an all-solid-state battery cell. The battery cell has 10 positive electrode layers, 11 negative electrode layers, and a capacity of 6Ah. The battery cell is subjected to isostatic pressing at 60℃ for 20 minutes.

[0086] Example 4

[0087] The specific steps for preparing an all-solid-state battery are as follows:

[0088] (1) Preparation of the negative electrode: Artificial hard carbon negative electrode material (70% dry powder by mass), Li6PS5Cl (26% dry powder by mass), SEBS binder (2% dry powder by mass), and VGCF conductive agent (2% dry powder by mass) are dispersed in xylene and stirred thoroughly to form a uniform and stable negative electrode material slurry. This slurry is then coated on both sides of a copper foil with a coating amount of 13.2 mg / cm². 2 After drying, a negative electrode with a thickness of 226 μm was obtained; the size of the negative electrode after cutting is 100 × 100 mm. 2 ;

[0089] (2) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a wet process using a polymer electrolyte (a mixture of PEO and LiTFSI in a 4:1 mass ratio) and polyvinylidene fluoride (PVDF). The solid electrolyte layer contained 98.5% polymer solid electrolyte and 1.5% polytetrafluoroethylene; its thickness was 20 μm, and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0090] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) is completely dissolved in xylene solvent, and lithium manganese iron phosphate cathode material (80% by mass of dry powder), VGCF (2% by mass of dry powder) and Li6PS5Cl (16% by mass of dry powder) are added and stirred thoroughly to form a stable cathode material slurry; aluminum foil with a size of 120×120mm is provided. 2A positive electrode material slurry is coated on both sides of the aluminum foil. The coating size is 102×98mm. 2 Coating surface density 27 mg / cm³ 2 A 170 μm thick layer forms the positive electrode material region. A chloroprene rubber CR slurry (CR powder and ceramic dispersed in xylene solvent at a mass ratio of 8:1, with a slurry solid content of 40%) is coated around the tab and the outer periphery of the positive electrode material region on the opposite side. The coating thickness is 180 μm, and the width is 4 mm. After drying, it is cut into 102 × 106 mm pieces. 2 For the positive electrode sheet, apply insulating tape of PET material with a thickness of 5μm, a width of 3mm, and a length of 102mm to the upper and lower surfaces of both sides of the positive electrode sheet that are not coated with CR paste, so as to completely cover the edge of the positive electrode sheet.

[0091] (4) Stack the negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, and negative electrode in that order, weld the tabs, and vacuum seal to prepare an all-solid-state battery cell. The battery cell has 30 positive electrode layers, 31 negative electrode layers, and a capacity of 6Ah. The battery cell is then subjected to hot pressing treatment at 70℃ for 15 minutes.

[0092] Example 5

[0093] The specific steps for preparing an all-solid-state battery are as follows:

[0094] (1) Preparation of the negative electrode: Silver-carbon negative electrode material (silver particles with a diameter of 50 nm, carbon as SP, with a mass ratio of 1:3 and a dry powder mass fraction of 65%), Li6PS5Cl (dry powder mass fraction of 31%), SEBS binder (dry powder mass fraction of 2%), and VGCF conductive agent (dry powder mass fraction of 2%) are dispersed in xylene solvent and stirred thoroughly to form a uniform and stable negative electrode material slurry. This slurry is coated on both sides of a copper foil, dried, and rolled to obtain a negative electrode with a thickness of 30 μm. The negative electrode size after cutting is 100 × 100 mm. 2 ;

[0095] (2) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a conventional solvent-free dry process using sulfide electrolyte (Li6PS5Cl) and polytetrafluoroethylene (PTFE). The solid electrolyte layer contained 97% solid electrolyte and 3.0% PTFE; its thickness was 15 μm, and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0096] (3) Preparation of composite cathode: SBS binder (2% by mass of dry powder) is completely dissolved in xylene solvent, and lithium cobalt oxide cathode material (80% by mass of dry powder), VGCF (2% by mass of dry powder) and Li6PS5Cl (16% by mass of dry powder) are added and stirred thoroughly to form a stable cathode material slurry; aluminum foil with size 120×120mm is provided.2 A positive electrode material slurry is coated on both sides of an aluminum foil. The coating size is 100×98mm. 2 Coating surface density 24 mg / cm³ 2 A 160μm thick layer forms the positive electrode material region. A room temperature vulcanizing silicone rubber slurry (room temperature vulcanizing silicone rubber and ceramic dispersed in toluene solvent at a mass ratio of 4:1, with a solid content of 40%) is coated around the tab and the opposite side of the positive electrode material region. The coating thickness is 180μm, and the width is 4mm. After drying, it is cut into 100×106mm pieces. 2 For the positive electrode sheet, attach insulating tape made of PET material, 5μm thick, 2mm wide, and 102mm long, to the upper and lower surfaces of both sides of the positive electrode sheet that are not coated with vulcanized silicone rubber slurry, so as to completely cover the edge of the positive electrode sheet.

[0097] (4) Stack the negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, and negative electrode in that order, weld the tabs, and vacuum seal to prepare an all-solid-state battery cell. The battery cell has 30 positive electrode layers, 31 negative electrode layers, and a capacity of 6Ah. The battery cell is subjected to isostatic pressing at 90℃ for 25 minutes.

[0098] Comparative Example 1

[0099] The difference from Example 1 is that the positive electrode is not coated with an insulating material area, but only coated with a positive electrode material slurry cut into 100×102mm pieces. 2 The positive electrode is not covered with tape.

[0100] Comparative Example 2

[0101] The difference from Example 2 is that the thickness of the insulating material region is 150 μm and the thickness of the positive electrode material region is 80 μm, which does not satisfy the relationship L-50 μm≤M≤L+30 μm.

[0102] Comparative Example 3

[0103] The difference from Example 3 is that no tape is applied.

[0104] Comparative Example 4

[0105] The difference from Example 4 is that the positive electrode is not coated with an insulating material area, but only coated with a positive electrode material slurry cut into 102×106mm pieces. 2 The positive electrode (i.e., only the tape is attached).

[0106] Comparative Example 5

[0107] The difference from Example 5 is that the dimensions of the insulating material area formed after coating with vulcanized silicone rubber and the outer edge of the insulating tape after pasting are both 1 mm smaller than the negative electrode layer.

[0108] Test example:

[0109] The performance of the all-solid-state batteries prepared in the examples and comparative examples was compared, including tests on indicators such as short-circuit rate, yield, and cycle performance:

[0110] The above-mentioned pouch batteries were tested for rate performance and cycle performance using a Blue Electric electrochemical tester. The initial charge was performed at 0.1C, with a discharge cutoff voltage of 2.5V and a charge cutoff voltage of 4.3V. After the initial charge, the batteries were allowed to rest for 10 minutes, followed by two charge-discharge cycles each at current densities of 0.2C, 1C, and 5C. Cycle performance was determined by performing 100 constant-current charge-discharge cycles at 0.5C. The test temperature was room temperature, and the voltage range was 2.8–4.3V. One hundred batteries were tested, and the short-circuit rate was compared. The experimental results are shown in Table 1.

[0111] Table 1

[0112]

[0113] Experimental results show that the all-solid-state batteries of Examples 1-5 exhibit significant advantages in short-circuit rate, yield, and cycle performance, effectively solving the short-circuit problem and improving battery performance and reliability. In contrast, Comparative Example 1, lacking an insulating zone and adhesive tape, experienced a short circuit after isostatic pressing; Comparative Example 2, with an insufficient insulation layer thickness, saw a decrease in short-circuit rate and yield, and its cycle performance was also affected; Comparative Example 3, lacking adhesive tape, experienced an increased short-circuit rate and a significant decrease in yield and cycle performance; Comparative Example 4, without an insulating layer, resulted in unstable battery performance; and in Comparative Example 5, the length and width of the coated insulating layer and the applied adhesive tape layer were smaller than the negative electrode layer, leading to an increased short-circuit rate and a decrease in yield and cycle performance.

[0114] Through the above embodiments and comparative experiments, it has been demonstrated that the all-solid-state battery structure and its preparation method of the present invention can effectively prevent short circuits, improve battery performance and reliability, and have broad application prospects.

[0115] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. An all-solid-state battery, characterized in that, The all-solid-state battery includes a solid electrolyte layer and alternating stacked positive and negative electrode plates, with the solid electrolyte layer positioned between the positive and negative electrode plates; the solid electrolyte layer and the negative electrode plates are of equal size; The positive electrode sheet includes a positive current collector and a coating layer on both sides of the positive current collector. The coating layer includes a positive electrode material region and an insulating material region on the outer periphery of two opposite sides of the positive electrode material region. The two opposite sides are the side where the tab is located and the side opposite to it. Along the direction of the side where the tab is located and the side opposite to it, the size of the positive electrode sheet is greater than or equal to the size of the solid electrolyte layer. Along the direction perpendicular to the side where the tab is located and the side opposite to it, the size of the positive electrode sheet is greater than the size of the solid electrolyte layer. The insulating material region is made of at least one of the following: PVDF and its modified materials, PAN and its modified materials, PI and its modified materials, natural rubber NR, styrene-butadiene rubber SBR, butyl rubber IIR, hydrogenated nitrile rubber HNBR, ethylene propylene rubber EPDM, nitrile rubber NBR, chloroprene rubber CR, silicone rubber, polyurethane, styrene-butadiene block copolymer rubber SBS and its modified performance material SEBS, polyisobutylene rubber PIB, or a mixture thereof with inorganic fillers; The positive electrode sheet is covered with insulating tape on both the upper and lower surfaces along the direction perpendicular to the side where the tab is located and the opposite side. The insulating tape covers all or part of the edge of the positive electrode sheet in the width direction. After the sheets are stacked and pressed, the insulating tape is pressed into the adjacent solid electrolyte layer in all or part. The insulating tape is made of at least one of PI, PE, PP, PET, and PEEK.

2. The all-solid-state battery according to claim 1, characterized in that, The thickness L of the insulating material region and the thickness M of the positive electrode material region satisfy the following relationship: L-50μm≤M≤L+30μm, where the units of L and M are μm.

3. The all-solid-state battery according to claim 1, characterized in that, The width of the insulating material area is 0.5 to 10 mm.

4. The all-solid-state battery according to claim 1, characterized in that, The thickness of the insulating tape is 1–20 μm.

5. The all-solid-state battery according to claim 1, characterized in that, The width of the insulating tape is 0.5 to 10 mm.

6. The all-solid-state battery according to any one of claims 1-5, characterized in that, The positive electrode material region comprises the following components by mass percentage: 70-94% positive electrode active material, 1-3% conductive agent, 1-3% binder, and 4-28% sulfide electrolyte; The positive electrode active material is selected from at least one of ternary materials, lithium iron phosphate, lithium cobalt oxide, lithium manganese iron phosphate, lithium-rich manganese-based materials, and sulfur positive electrode materials.

7. The all-solid-state battery according to any one of claims 1-5, characterized in that, The negative electrode sheet includes a negative electrode current collector and negative electrode material layers on both sides. The negative electrode material layers include the following components by mass percentage: 60-90% negative electrode active material, 1-3% conductive agent, 1-3% binder, and 4-38% sulfide electrolyte. The negative electrode active material is selected from at least one of carbon materials, silicon negative electrode materials, tin negative electrode materials, lithium metal negative electrode materials, and lithium-free negative electrode materials.

8. The all-solid-state battery according to any one of claims 1-5, characterized in that, The solid electrolyte layer comprises the following components by weight percentage: 95-99.5% solid electrolyte and 0.5-5% binder; The solid electrolyte is selected from at least one of sulfide electrolytes, oxide electrolytes, chloride electrolytes, and polymer electrolytes.

9. A method for preparing an all-solid-state battery according to any one of claims 1-8, characterized in that, Includes the following steps: (a) Prepare a solid electrolyte layer by coating a negative electrode material slurry on both sides of the negative electrode current collector and drying it to obtain a negative electrode sheet with a negative electrode material layer on both sides. Cut the solid electrolyte layer to make the size of the solid electrolyte layer equal to the size of the negative electrode sheet. (b) First, a positive electrode material slurry is coated on both sides of the positive electrode current collector. After drying, a positive electrode material region is formed. Then, an insulating material slurry is coated around the positive electrode material region located on the side where the tab is located and on the opposite side. After drying, an insulating material region is formed. Alternatively, a positive electrode material slurry is coated in the middle and an insulating material slurry is coated on the edge at the same time. After drying, a positive electrode sheet containing a positive electrode material region and an insulating material region is formed. The sheet is cut so that the dimensions of the positive electrode material region and the insulating material region along the direction perpendicular to the side where the tab is located and on the opposite side are larger than the dimensions of the solid electrolyte layer. The dimensions of the positive electrode material region along the direction where the tab is located and on the opposite side are greater than or equal to the dimensions of the solid electrolyte layer. Insulating tape is pasted on the upper and lower surfaces of the positive electrode sheet along the two sides perpendicular to the side where the tab is located and on the opposite side, so that the width of the insulating tape covers all or part of the edge of the positive electrode sheet, thus obtaining a composite positive electrode sheet. (c) Stack the negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer and negative electrode in sequence to obtain the battery cell; and apply pressure to the battery cell.

10. The preparation method according to claim 9, characterized in that, The pressurization method in step (c) includes one of isostatic pressing, flat plate pressing, and roller pressing. The pressurization temperature is 0 to 1000℃, the pressurization time is 0.5 to 30 minutes, and the pressurization pressure is 3 to 1000 MPa.

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