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

Abstract

This invention provides an all-solid-state battery and its fabrication 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. The positive electrode includes a positive current collector and two positive electrode material layers on each side. Each positive electrode material layer has an elastic insulating frame layer, which is a hollow quadrilateral frame structure. The perimeter of the positive electrode material layer is partially covered by the elastic insulating frame layer. This invention effectively prevents short circuits caused by shearing at the edges of the positive and negative electrode sheets under high voltage by covering the perimeter of the positive electrode material layer with a highly elastic and tough ion / electron insulating layer.

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 membrane ("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 smaller than the negative electrode after being stacked and centered), the edge of the positive electrode will exert shear force on the electrolyte layer when the stacked materials are subjected to isostatic pressing or flat plate pressing. This can easily cause the edge 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, with a large number of stacked layers, in order to better reduce the cell impedance of multiple interfaces, the pressure and time of the pressurization will be appropriately increased, which makes it easier to cause indentation and damage to the 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 that effectively prevents short circuits and improves battery yield and safety by covering the perimeter of the positive electrode material layer with a highly elastic and tough insulating frame.

[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 alternating stacked positive and negative electrode plates, wherein the solid electrolyte layer is located between the positive and negative electrode plates, the size of the positive electrode plate is smaller than the size of the negative electrode plate, and the size of the solid electrolyte layer is equal to the size of the negative electrode plate;

[0011] The positive electrode sheet includes a positive current collector and two positive electrode material layers. Each positive electrode material layer is provided with an elastic insulating frame layer. The elastic insulating frame layer is a hollow quadrilateral frame structure. The positive electrode material layer is partially covered by the elastic insulating frame layer. The inner frame size of the elastic insulating frame layer is smaller than the size of the positive electrode sheet, and the outer frame size is larger than the size of the positive electrode sheet.

[0012] After being stacked and pressurized, the elastic insulating frame layer is compressed between the positive electrode material layer and the adjacent solid electrolyte layer.

[0013] Unless otherwise specified, the dimensional relationships mentioned herein refer to length to length ratio and width to width ratio.

[0014] The cross-sectional structure of the battery cell before pressure after lamination assembly in this invention is as follows: Figure 1 As shown, from bottom to top, the layers are: negative electrode 2, solid electrolyte layer 3, elastic insulating frame layer 4, positive electrode 1, elastic insulating frame layer 4, solid electrolyte layer 3, negative electrode 2, solid electrolyte layer 3, elastic insulating frame layer 4, positive electrode 1... That is, the elastic insulating frame layer 4 is composited on the positive electrode material layers on both sides of the positive electrode 1. The elastic insulating frame layer 4 is a quadrilateral frame that partially covers the edges of the positive electrode material layers. The cross-sectional structure of the cell under pressure is shown below. Figure 2 As shown, the elastic insulating frame layer 4 will be further compressed between the positive electrode 1 and the solid electrolyte layer 3 under pressure.

[0015] The dimensional relationships of each part are as follows: the inner frame size of the elastic insulating frame is smaller than the positive electrode sheet (positive electrode material layer), and the outer frame size is larger than the positive electrode sheet (positive electrode material layer). That is, the elastic insulating frame can partially cover the edge of the positive electrode sheet (positive electrode material layer). This design ensures that when the positive electrode sheet moves under pressure, the edge of the positive electrode sheet remains within the width of the insulating frame due to the high elastic deformation. This prevents the shearing action generated at the edge of the positive electrode sheet during the pressurization process from damaging the electrolyte, thereby causing a short circuit between the positive and negative electrodes. It is understood that the inner frame size of the elastic insulating frame is also smaller than the negative electrode sheet. There are no special requirements for the outer frame size and the size of the negative electrode sheet, but it is preferable that the outer frame size is greater than or equal to the size of the negative electrode sheet.

[0016] Flexible insulating frame layer (quadrilateral frame):

[0017] The elastic insulating frame layer of this invention is a highly elastic and tough ionic / electronic insulating layer. Its material is selected from at least one of the following: natural rubber (NR), styrene-butadiene rubber (SBR), butyl rubber (IIR), hydrogenated nitrile rubber (HNBR), ethylene propylene diene monomer (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. These materials possess excellent insulation properties, elasticity, and toughness, meeting the requirements for battery use.

[0018] In some embodiments, the elastic modulus of the material of the elastic insulating frame layer is between 1 and 100 MPa, and the elongation at break is between 30% and 1000%. This allows the insulating layer to maintain good elasticity and mechanical properties during battery charging and discharging, preventing the insulating layer from cracking or being damaged.

[0019] In some implementations, the thickness of the elastic insulating frame layer is 0.5-20 μm. Within this thickness range, the insulating frame can effectively resist the shearing damage caused by the edge of the positive electrode during the cell pressurization process without affecting other performance characteristics of the cell.

[0020] In some implementations, the difference between the outer frame dimension and the inner frame dimension of the elastic insulating frame layer (twice the frame width) is 0.5-20 mm. That is, the width is 0.2-10 mm.

[0021] The flexible insulating frame can be a single structure or composed of four frame strips.

[0022] Positive electrode tablets:

[0023] The positive electrode sheet includes a positive current collector and positive electrode material layers on both sides. The positive electrode material layers include the following components by mass percentage: 70-94% positive electrode active material, 1-3% conductive agent, 1-3% binder, and 4-28% sulfide electrolyte.

[0024] In some implementations, the positive current collector is aluminum foil;

[0025] 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).

[0026] 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.

[0027] 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.

[0028] 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).

[0029] The thickness of the positive electrode can be 30–450 μm.

[0030] Negative electrode plate:

[0031] 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.

[0032] In some implementations, the negative current collector is copper foil;

[0033] 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).

[0034] 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.

[0035] 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.

[0036] 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).

[0037] The thickness of the negative electrode can be 20–400 μm.

[0038] Solid electrolyte layer:

[0039] The solid electrolyte layer comprises the following components by mass percentage: 95–99.5% solid electrolyte and 0.5–5% binder.

[0040] 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).

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

[0043] Secondly, the present invention provides a method for preparing the above-mentioned all-solid-state battery, comprising the following steps:

[0044] (a) Prepare a solid electrolyte layer by coating a negative electrode material slurry on both sides of the negative electrode current collector, drying it to obtain a negative electrode sheet, and cutting it so that the size of the solid electrolyte layer is equal to the size of the negative electrode sheet;

[0045] (b) A positive electrode material slurry is coated on both sides of the positive electrode current collector and dried to obtain a positive electrode sheet with positive electrode material layers on both sides. The positive electrode sheet is cut so that its size is smaller than that of the negative electrode sheet. A hollow quadrilateral frame structure is prepared using an elastic insulating material to obtain an elastic insulating frame layer. The inner frame size of the elastic insulating frame layer is smaller than that of the positive electrode sheet, and the outer frame size is larger than that of the positive electrode sheet. The elastic insulating frame layer is composited onto the positive electrode material layers on both sides so that the elastic insulating frame layer partially covers the perimeter of the positive electrode material layer to obtain a composite positive electrode sheet.

[0046] (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.

[0047] The elastic insulating frame layer can be integrally injection molded from elastic insulating material to the required size and then laminated with the positive electrode sheet (this lamination can be achieved through bonding). Alternatively, it can be prepared by coating an elastic insulating material slurry onto a substrate, drying it, and then peeling it off the substrate and cutting it to the required size. Both methods can effectively prepare short-circuit resistant elastic insulating layers. The choice of method depends on actual production needs and process conditions.

[0048] 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.

[0049] Beneficial effects:

[0050] The high-elasticity and high-toughness insulating frame covering the positive electrode layer of this invention can elongate and deform with the displacement of the positive electrode during the cell pressurization process, ensuring that the edge of the positive electrode will not come into contact with the negative electrode due to shear effect. At the same time, the material of the insulating layer has good elasticity and toughness, and can withstand the expansion and contraction of the positive and negative electrode sheets during isostatic pressure and battery charging and discharging, thereby maintaining stable insulation performance.

[0051] 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

[0052] Figure 1 This is a cross-sectional view of a cell structure before pressure is applied during the stacking of an all-solid-state battery according to one embodiment of the present invention.

[0053] Figure 2 This is a cross-sectional view of a cell structure after being compressed during the stacking of all-solid-state batteries according to one embodiment of the present invention;

[0054] Diagram: 1-Positive electrode; 2-Negative electrode; 3-Solid electrolyte layer; 4-Elastic insulating frame layer. Detailed Implementation

[0055] 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.

[0056] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0057] Example 1

[0058] The specific steps for preparing an all-solid-state battery are as follows:

[0059] (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 ;

[0060] (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 99.5% oxide solid electrolyte and 0.5% PTFE; its thickness was 50 μm, and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0061] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene, 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; the cathode material slurry was coated on both sides of the aluminum foil, with a coating size of 98×98mm. 2 Surface density 22 mg / cm³ 2 The material is dried and rolled to form a positive electrode material layer with a thickness of 150μm, and then cut to obtain a positive electrode sheet. SBR is injected into a square frame with an inner frame of 97×97mm and an outer frame of 103×103mm, with a thickness of 10μm, to obtain an elastic insulating frame layer. Then, the elastic insulating frame layer is bonded to the positive electrode material layers on both sides of the positive electrode, partially covering the perimeter of the positive electrode material layer, to obtain a composite positive electrode.

[0062] (4) Stack the electrodes in the following order: negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, negative electrode. Weld the tabs and vacuum seal the electrode to prepare an all-solid-state battery cell. The battery cell has 10 positive electrode layers and 11 negative electrode layers, with a capacity of 6Ah. The battery cell is subjected to isostatic pressing at 50°C for 15 minutes.

[0063] Example 2

[0064] The specific steps for preparing an all-solid-state battery are as follows:

[0065] (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 metal layer on each side is 20 μm thick. The negative electrode size after cutting is 100 × 100 mm. 2 ;

[0066] (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 98.5% solid electrolyte and 1.5% PTFE; its thickness was 80 μm, and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0067] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) was 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) were added and stirred thoroughly to form a stable cathode material slurry; the cathode material slurry was coated on both sides of the aluminum foil, with a coating size of 98×98mm. 2 Coating surface density: 19.5 mg / cm³ 2 The thickness is 100μm. After drying, the positive electrode sheet with positive electrode material layers on both sides is obtained. Hydrogenated nitrile rubber is injected into a square frame with an inner frame of 97×97mm and an outer frame of 103×103mm, with a thickness of 10μm, to obtain an elastic insulating frame layer. Then, the elastic insulating frame layer is bonded to the positive electrode material layers on both sides of the positive electrode, partially covering the perimeter of the positive electrode material layers, to obtain a composite positive electrode.

[0068] (4) Stack the electrodes in the following order: negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, negative electrode. Weld the tabs and vacuum seal the electrode to prepare an all-solid-state battery cell. The battery cell has 10 positive electrode layers and 11 negative electrode layers, with a capacity of 6Ah. The battery cell is then subjected to hot pressing treatment at 100℃ for 10 minutes.

[0069] Example 3

[0070] The specific steps for preparing an all-solid-state battery are as follows:

[0071] (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 layer slurry. This negative electrode material slurry was then coated on both sides of a copper foil with a coating amount of 6.1 mg / cm². 2After 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 ;

[0072] (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 (PTFE). The solid electrolyte layer contained 99% solid electrolyte and 1% PTFE; its thickness was 100 μm, and the dimensions of the cut solid electrolyte layer were 100 × 100 mm. 2 ;

[0073] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene solvent, and lithium iron phosphate (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; the cathode material slurry was coated on aluminum foil with a coating size of 97×97mm. 2 The coating thickness is 230μm. After drying and rolling, a positive electrode material layer is formed, which is then cut to obtain a positive electrode sheet. Ethylene propylene diene monomer (EPDM) (molecular weight 300,000) is injected into a square frame with an inner frame of 96×96mm and an outer frame of 101×101mm, with a thickness of 15μm, to obtain an elastic insulating frame layer. Then, the elastic insulating frame layer is bonded to the positive electrode material layers on both sides of the positive electrode, partially covering the perimeter of the positive electrode material layer, to obtain a composite positive electrode.

[0074] (4) Stack the electrodes in the following order: negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, negative electrode. Weld the tabs and vacuum seal the electrode to prepare an all-solid-state battery cell. The battery cell has 10 positive electrode layers and 11 negative electrode layers, with a capacity of 6Ah. The battery cell is subjected to isostatic pressing at 60°C for 20 minutes.

[0075] Example 4

[0076] The specific steps for preparing an all-solid-state battery are as follows:

[0077] (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 ;

[0078] (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 ;

[0079] (3) Preparation of composite cathode: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene solvent, and lithium manganese iron phosphate (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; the cathode material slurry was coated on both sides of the aluminum foil, with a coating size of 98×98mm. 2 Coating thickness 170μm, areal density 27mg / cm³ 2 The cathode sheet with positive electrode material layers on both sides is obtained by drying and cutting. Chloroprene rubber and ceramic inorganic filler (D50 is 1.5μm) are blended by twin screw press at a mass ratio of 4:1 and injected into a square frame with an inner frame of 97×97mm and an outer frame of 103×103mm, with a thickness of 14μm, to obtain an elastic insulating frame layer. The elastic insulating frame layer is then bonded to the positive electrode material layer, partially covering the perimeter of the positive electrode material layer, to obtain a composite positive electrode.

[0080] (4) Stack the electrodes in the following order: negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, negative electrode. Weld the tabs and vacuum seal the electrode to prepare an all-solid-state battery cell. The battery cell has 30 positive electrode layers and 31 negative electrode layers, with a capacity of 6Ah. The battery cell is then subjected to hot pressing treatment at 70°C for 15 minutes.

[0081] Example 5

[0082] The specific steps for preparing an all-solid-state battery are as follows:

[0083] (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 ;

[0084] (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 ;

[0085] (3) Preparation of composite cathode: SBS binder (2% by mass of dry powder) was completely dissolved in xylene solvent, and lithium cobalt oxide (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; the cathode material slurry was coated on both sides of aluminum foil, with a coating size of 98×98mm. 2 The coating thickness is 170 μm, and the areal density is 24 mg / cm³. 2 After drying, rolling, and cutting, a positive electrode sheet with positive electrode material layers on both sides is formed; room temperature vulcanized silicone rubber is injected into a square frame with an inner frame of 97×97mm and an outer frame of 103×103mm, with a thickness of 10μm, to obtain an elastic insulating frame layer. Then, the elastic insulating frame layer is bonded to the positive electrode material layers on both sides of the positive electrode, partially covering the perimeter of the positive electrode material layers, to obtain a composite positive electrode.

[0086] (4) Stack the electrodes in the following order: negative electrode, solid electrolyte layer, composite positive electrode, solid electrolyte layer, negative electrode. Weld the tabs and vacuum seal the electrode to prepare an all-solid-state battery cell. The battery cell has 10 positive electrode layers and 11 negative electrode layers, with a capacity of 6Ah. The battery cell is subjected to isostatic pressing at 90℃ for 25 minutes.

[0087] Comparative Example 1

[0088] The difference from Example 1 is that the SBR elastic insulating frame layer is not provided.

[0089] Comparative Example 2

[0090] The difference from Example 2 is that the thickness of the elastic insulating frame layer is 25μm, which does not meet the requirement of a thickness of 0.5-20μm.

[0091] Comparative Example 3

[0092] The difference from Example 3 is that the EPDM has a molecular weight of 100,000, an elastic modulus of 0.1 MPa, and an elongation at break of 20%, which does not meet the requirements.

[0093] Comparative Example 4

[0094] The difference from Example 4 is that the outer frame of the insulating frame is 0.5 mm smaller than the size of the positive electrode sheet.

[0095] Comparative Example 5

[0096] The difference from Example 4 is that the inner frame of the insulating frame is 0.5 mm larger than the positive electrode sheet.

[0097] Test example:

[0098] 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 and cycle performance:

[0099] 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.

[0100] Table 1

[0101]

[0102]

[0103] 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 elastic insulating layer, experienced a short circuit during charging; Comparative Example 2, with an insufficiently thick elastic insulating layer, saw an increased short-circuit rate, a decreased yield, and some impact on cycle performance; Comparative Example 3, with insufficient elastic modulus and elongation at break of the elastic insulating layer material, experienced an increased short-circuit rate and a significant decrease in yield and cycle performance; Comparative Example 4, with an insulating frame smaller than the positive electrode size, caused the positive electrode edge to shear and recombine with the negative electrode, increasing the battery's short-circuit rate and causing performance instability; Comparative Example 5, with an inner frame larger than the positive electrode size, caused the positive electrode edge to shear and recombine with the negative electrode during pressurization, further increasing the battery's short-circuit rate, decreasing yield, and reducing cycle performance. Through these examples and comparative experiments, it is demonstrated that the all-solid-state battery structure and its preparation method of this invention can effectively prevent short circuits, improve battery performance and reliability, and have broad application prospects.

[0104] 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 located between the positive and negative electrode plates. The size of the positive electrode plate is smaller than that of the negative electrode plate, and the size of the solid electrolyte layer is equal to that of the negative electrode plate. The positive electrode sheet includes a positive current collector and two positive electrode material layers. Each positive electrode material layer has an elastic insulating frame layer. The elastic insulating frame layer is a hollow quadrilateral frame structure. The positive electrode material layer is partially covered by the elastic insulating frame layer. The inner frame size of the elastic insulating frame layer is smaller than the size of the positive electrode sheet, and the outer frame size is larger than the size of the positive electrode sheet. After stacking and pressing, the elastic insulating frame layer is compressed between the positive electrode material layer and the adjacent solid electrolyte layer.

2. The all-solid-state battery according to claim 1, characterized in that, The thickness of the elastic insulating frame layer before compression is 0.5-20 μm.

3. The all-solid-state battery according to claim 1, characterized in that, The material of the elastic insulating frame layer is selected from at least one of natural rubber, styrene-butadiene rubber, butyl rubber, hydrogenated nitrile rubber, ethylene propylene rubber, nitrile rubber, chloroprene rubber, silicone rubber, polyurethane, styrene-butadiene block copolymer rubber and its modified materials, polyisobutylene rubber, or a mixture thereof with inorganic fillers.

4. The all-solid-state battery according to claim 3, characterized in that, The elastic modulus of the material of the elastic insulating frame layer is 1 to 100 MPa, and the elongation at break is 30% to 1000%.

5. The all-solid-state battery according to claim 1, characterized in that, The width of the elastic insulating frame layer before compression is 0.2-10mm.

6. The all-solid-state battery according to any one of claims 1-5, characterized in that, The positive electrode material layer comprises the following components by weight 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, drying it to obtain a negative electrode sheet, and cutting it so that the size of the solid electrolyte layer is equal to the size of the negative electrode sheet; (b) A positive electrode material slurry is coated on both sides of the positive electrode current collector and dried to obtain a positive electrode sheet with positive electrode material layers on both sides. The positive electrode sheet is cut so that its size is smaller than that of the negative electrode sheet. A hollow quadrilateral frame structure is prepared using an elastic insulating material to obtain an elastic insulating frame layer. The inner frame size of the elastic insulating frame layer is smaller than that of the positive electrode sheet, and the outer frame size is larger than that of the positive electrode sheet. The elastic insulating frame layer is composited onto the positive electrode material layers on both sides so that the elastic insulating frame layer partially covers the perimeter of the positive electrode material layer to obtain 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 pressing method in step (c) 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 pressure is 3–1000MPa.

Images