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 electrode sheets, with the solid electrolyte layer situated between the positive and negative electrode sheets. An insulating frame layer is also provided between the positive and negative electrode sheets. The insulating frame layer is a hollow quadrilateral frame structure, with the inner frame dimension smaller than the positive electrode sheet dimension and the outer frame dimension larger than the positive electrode sheet dimension. This invention can prevent the shearing action generated at the electrode edges under high voltage from damaging the structural integrity of the electrolyte layer, thus preventing short circuits caused by contact between the positive and negative electrode sheets. This significantly improves the yield of lithium-ion batteries, reduces the short-circuit rate, and improves the cycle performance of the batteries.

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] Energy shortages and environmental pollution are two major global challenges. Considering the energy supply and exhaust pollution issues associated with traditional automobiles, developing new energy vehicles has become a crucial need for countries worldwide, and the complete replacement of traditional gasoline-powered vehicles by new energy vehicles is now on the agenda. For new energy vehicles to continue competing with traditional gasoline-powered vehicles in the market, they must be comparable in terms of range and cost. This requires battery cell energy density to reach 350Wh / kg or even higher. However, as the energy density of individual batteries increases, so does the safety risk. Improving the safety of power batteries has become a key focus for the industry. Solid-state batteries, which use solid electrolytes, can reduce or even eliminate the use of liquid electrolytes, theoretically effectively reducing the probability of fires and explosions. They are considered to address the safety issues of new energy vehicles at their root and have become a key development direction in the power battery field.

[0003] 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 and negative electrodes (the negative electrode is larger than the positive electrode), the edge of the positive electrode will exert shear force on the electrolyte layer during isostatic pressing or flat plate pressing during the stacking assembly. This can easily cause the edge of the positive electrode to pierce the electrolyte layer and come into contact with the negative electrode, resulting in a short circuit in the battery. This affects the performance and reliability of the battery. Moreover, as the number of stacked electrodes increases, the possibility of the positive electrode causing shearing, indentation or damage to the electrolyte layer is higher, and the probability of a short circuit between the positive and negative electrodes is greater. Summary of the Invention

[0004] To address at least one of the problems in the prior art, the present invention provides an all-solid-state battery that, by setting a high-strength, high-modulus insulating frame, can reduce the short-circuit rate of the solid-state battery and improve its cycle performance.

[0005] One of the objectives of this invention is to provide an all-solid-state battery.

[0006] The second objective of this invention is to provide a method for preparing the all-solid-state battery.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] 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 positive electrode plate is smaller than the negative electrode plate (i.e., the length of the positive electrode plate is slightly smaller than the length of the negative electrode plate, and the width of the positive electrode plate is slightly smaller than the width of the negative electrode plate), and the solid electrolyte layer is equal to the negative electrode plate (length and width are equal).

[0009] An insulating frame layer is provided between the positive electrode and the negative electrode. The insulating frame layer is a hollow quadrilateral frame structure, with the inner frame size smaller than the positive electrode size and the outer frame size larger than the positive electrode size; the thickness of the insulating frame layer is 0.5 to 20 μm.

[0010] After stacking and pressurizing, the insulating frame layer is embedded or partially embedded in the adjacent solid electrolyte layer.

[0011] In this invention, the positive electrode sheet is smaller than the negative electrode sheet. This size difference makes it easy for the edge of the positive electrode sheet to pierce the electrolyte layer during pressing, thus contacting the negative electrode sheet and causing a short circuit in the battery. To solve this problem, this invention inserts a high-strength, high-modulus insulating frame between the positive and negative electrode sheets, preventing the edge of the positive electrode from damaging the electrolyte layer or the negative electrode and causing a short circuit after being pressed.

[0012] In some implementations, the cross-sectional structure of the cell before pressure application after lamination assembly is as follows: Figure 1 As shown, from bottom to top, the layers are: negative electrode 2, solid electrolyte layer 3, insulating frame layer 4, positive electrode 1, insulating frame layer 4, solid electrolyte layer 3, negative electrode 2, solid electrolyte layer 3, insulating frame layer 4, positive electrode 1... That is, the insulating frame layer 4 is entirely located between the positive electrode 1 and the solid electrolyte layer 3. The cross-sectional structure of the cell under pressure is shown below. Figure 2 As shown, the insulating frame layer 4 is embedded or partially embedded in the adjacent solid electrolyte layer 3.

[0013] In other embodiments, the cross-sectional structure of the cell before pressure application after lamination assembly is as follows: Figure 3 As shown, from bottom to top, the layers are: negative electrode 2, solid electrolyte layer 3, insulating frame layer 4, positive electrode 1, solid electrolyte layer 3, insulating frame layer 4, negative electrode 2, solid electrolyte layer 3, insulating frame layer 4, positive electrode 1, solid electrolyte layer 3, insulating frame layer 4, negative electrode 2... That is, the insulating frame layer 4 is alternately located between the positive electrode 1 and the solid electrolyte layer 3, and between the negative electrode 2 and the solid electrolyte layer 3 (i.e., it is located between the positive electrode 1 and the solid electrolyte layer 3 one time, and between the negative electrode 2 and the solid electrolyte layer 3 the next time). The cross-sectional structure of the cell under pressure is shown below. Figure 4 As shown, the insulating frame layer 4 is embedded or partially embedded in the adjacent solid electrolyte layer 3.

[0014] Dimensional diagrams of each part are shown below. Figure 5As shown in the figure, the dimensional relationships are as follows: e < a < c, f < b < d, f < h, e < g; h = n; g = m; the inner frame size of the insulating frame is smaller than that of the positive electrode plate, and the outer frame size is larger than that of the positive electrode plate, that is, the edge of the positive electrode plate is within the range of the insulating frame (equivalent to the positive electrode plate being supported on the insulating frame, and the insulating frame partially covers the positive electrode plate). Such a design can prevent the electrolyte from being damaged by the shearing force generated at the edge of the positive electrode plate during the pressurization process of the battery cell, thereby causing short circuit between the positive and negative electrode plates; it can be understood that the inner frame size of the insulating frame is also smaller than that of the negative electrode plate, and there are no special requirements for the outer frame size of the insulating frame compared with that of the negative electrode plate, which can be slightly larger, slightly smaller or equal. Preferably, the outer frame size is greater than or equal to the size of the negative electrode plate.

[0015] Unless otherwise specified, the dimensional relationships mentioned in the present invention herein refer to the comparison of length with length and width with width.

[0016] The thickness of the insulating frame layer of the present invention is 0.5 - 20 μm. Within this thickness range, the insulating frame can effectively resist the shearing and damaging effect generated at the edge of the positive electrode plate during the pressurization process of the battery cell, and does not affect other properties of the battery cell. If the thickness is too thin, the effect of resisting the shearing damage of the positive electrode plate is not good, and the risk of short circuit increases. If the thickness is too thick, in a multi-layer battery, due to the frame, the thickness around the battery cell will be higher than the center area without the frame, which is likely to cause the positive electrode plate to break, and may also cause the battery cell to be unable to be pressurized during the later application process due to inconsistent thickness, affecting the performance of the battery cell.

[0017] Insulating frame layer (quadrilateral frame structure):

[0018] In some embodiments, the material of the insulating frame layer includes one or more of polytetrafluoroethylene and its copolymers, polyvinylidene fluoride and its copolymers, polyethylene and its copolymers, polypropylene and its copolymers, polyimide, polyetherimide, aramid, PET, PEEK. Preferably, the tensile strength of these materials is ≥ 20 MPa, the elastic modulus is ≥ 0.1 GPa, and the compressive strength is ≥ 10 MPa; if the strength and modulus are lower than this range, the effect of the insulating frame resisting the shearing damage of the positive electrode plate will be weakened, and the short circuit rate of the battery will increase.

[0019] In some embodiments, the difference between the outer frame size and the inner frame size of the quadrilateral frame of the insulating frame layer (i.e., 2 × width) is 0.5 - 20 mm, that is, 0.5 mm < c - e < 20 mm; 0.5 mm < d - f < 20 mm.

[0020] The quadrilateral frame structure can be an integral structure or composed of four side frames.

[0021] Positive electrode plate:

[0022] 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.

[0023] In some implementations, the positive current collector is aluminum foil;

[0024] 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).

[0025] 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.

[0026] 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.

[0027] 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).

[0028] The thickness of the positive electrode can be 30–450 μm.

[0029] Negative electrode plate:

[0030] 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.

[0031] In some implementations, the negative current collector is copper foil;

[0032] 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).

[0033] 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.

[0034] 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.

[0035] 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).

[0036] The thickness of the negative electrode can be 20–400 μm.

[0037] Solid electrolyte layer:

[0038] The solid electrolyte layer comprises the following components by mass percentage: 95–99.5% solid electrolyte and 0.5–5% binder.

[0039] In some embodiments, the solid electrolyte is at least one selected from sulfide electrolytes, oxide electrolytes, chloride electrolytes, and polymer electrolytes; preferably lithium phosphorus sulfide chloride (Li6PS5Cl).

[0040] 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.

[0041] The thickness of the solid electrolyte layer can be 5–200 μm.

[0042] Secondly, the present invention provides a method for preparing the above-mentioned all-solid-state battery, comprising one of the following methods:

[0043] Method 1:

[0044] A solid electrolyte layer is provided; a negative electrode material slurry is coated on both sides of the negative electrode current collector and dried to obtain a negative electrode sheet; a positive electrode material slurry is coated on both sides of the positive electrode current collector and dried to obtain a positive electrode sheet; the solid electrolyte layer is cut to make the size of the solid electrolyte layer equal to the size of the negative electrode sheet, and the size of the positive electrode sheet is smaller than the size of the negative electrode sheet;

[0045] A hollow quadrilateral frame structure insulating frame layer is provided, wherein the inner frame size of the 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; the thickness of the insulating frame layer is 0.5–20 μm; the insulating frame layer is composited onto a solid electrolyte layer to obtain a composite solid electrolyte layer;

[0046] The electrodes are stacked sequentially in the following order: negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer, and negative electrode. The insulating frame layer is connected to the positive electrode to obtain the battery cell (e.g., ...). Figure 1 (as shown);

[0047] The battery cell is pressurized to obtain a pressurized battery cell (such as...). Figure 2 (as shown);

[0048] Method 2:

[0049] A solid electrolyte layer is provided; a negative electrode material slurry is coated on both sides of the negative electrode current collector and dried to obtain a negative electrode sheet; a positive electrode material slurry is coated on both sides of the positive electrode current collector and dried to obtain a positive electrode sheet; the solid electrolyte layer is cut to make the size of the solid electrolyte layer equal to the size of the negative electrode sheet, and the size of the positive electrode sheet is smaller than the size of the negative electrode sheet;

[0050] A hollow quadrilateral frame structure insulating frame layer is provided, wherein the inner frame size of the 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; the thickness of the insulating frame layer is 0.5–20 μm; the insulating frame layer is composited onto a solid electrolyte layer to obtain a composite solid electrolyte layer;

[0051] The electrodes are stacked sequentially in the following order: negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer, and negative electrode. The insulating frame layer is alternately connected to the positive and negative electrodes to obtain the battery cell (e.g., ...). Figure 3 (as shown);

[0052] The battery cell is pressurized to obtain a pressurized battery cell (such as...). Figure 4 (As shown).

[0053] The positive electrode, solid electrolyte layer, and negative electrode are obtained through conventional processes; then the positive electrode, solid electrolyte layer, and negative electrode are cut.

[0054] When the insulating frame is combined with the solid electrolyte layer, electrostatic adsorption or adhesive coating can be used.

[0055] Preferably, the pressurization method includes one of isostatic pressing, flat plate pressing, and roller pressing, with a pressurization temperature of 0 to 1000°C, a pressurization time of 0.5 to 30 minutes, and a pressure of 3 to 1000 MPa.

[0056] Beneficial effects:

[0057] This invention involves composited with a high-strength, high-modulus insulating frame layer on a solid electrolyte layer between the positive and negative electrodes. Under pressure, the frame structure is partially or completely embedded within the solid electrolyte layer, with the edge of the positive electrode within the insulating frame. This design prevents the shearing action at the electrode edges under high pressure from damaging the structural integrity of the electrolyte layer, thus preventing short circuits caused by contact between the positive and negative electrodes. This significantly improves the yield rate of lithium-ion batteries, reduces the short-circuit rate, and enhances cycle performance.

[0058] 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

[0059] 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.

[0060] 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;

[0061] Figure 3 This is a cross-sectional view of the cell structure before pressure is applied during the stacking of an all-solid-state battery according to another embodiment of the present invention.

[0062] Figure 4 This is a cross-sectional view of a cell structure after being compressed during the stacking of all-solid-state batteries according to another embodiment of the present invention;

[0063] Figure 5 This is a schematic diagram showing the dimensions of each part of the all-solid-state battery of the present invention.

[0064] Diagram: 1-Positive electrode; 2-Negative electrode; 3-Solid electrolyte layer; 4-Insulating frame layer. Detailed Implementation

[0065] 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.

[0066] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0067] Example 1

[0068] The specific steps for preparing an all-solid-state battery are as follows:

[0069] (1) Preparation of the positive electrode sheet: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene solvent. 811 ternary positive electrode material (80% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder), and Li6PS5Cl (16% by mass of dry powder) were added and stirred thoroughly to form a stable positive electrode material slurry. This slurry was then coated onto both sides of a 12μm thick aluminum foil with a coating amount of 18mg / cm². 2 After drying, the positive electrode sheet is rolled to obtain a thickness of 150μm. The size of the positive electrode sheet after cutting is 57×77mm. 2 (i.e., 57mm×77mm);

[0070] (2) Preparation of the negative electrode sheet: The silicon suboxide negative electrode material (60% by mass of dry powder), Li6PS5Cl (36% by mass of dry powder), SEBS binder (2% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder), and xylene solvent were thoroughly stirred to form a uniform and stable negative electrode material slurry. This slurry was then coated onto both sides of a 6μm copper foil with a coating amount of 5 mg / cm². 2 After drying, a negative electrode sheet with a thickness of 86μm was obtained. The size of the negative electrode sheet after cutting is 60×80mm. 2 ;

[0071] (3) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a conventional solvent-free dry process using a 651-type sulfide solid electrolyte, Li6PS5Cl, and polytetrafluoroethylene (PTFE). The solid electrolyte layer contained 99.5% 651-type sulfide solid electrolyte and 0.5% PTFE; its thickness was 50 μm, and the dimensions of the cut solid electrolyte layer were 60 × 80 mm. 2 ;

[0072] (4) Provide a hollow quadrilateral frame structure with an insulating frame layer: made of polytetrafluoroethylene, with a thickness of 1μm, a tensile strength of 30MPa, an elastic modulus of 0.2GPa, a compressive strength of 15MPa, and inner frame dimensions after cutting: 55×75mm. 2 Outer frame dimensions: 62×82mm 2 .

[0073] (5) The insulating frame layer is laminated onto one side of the solid electrolyte layer to obtain the composite solid electrolyte layer; the negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer and negative electrode are stacked in sequence (the geometric centers of the positive electrode, solid electrolyte layer, negative electrode and insulating frame are aligned), and the insulating frame layer is connected to the positive electrode to obtain the battery cell. The number of positive and negative electrode layers of the battery cell is 10 positive and 11 negative, and the designed capacity is 2Ah.

[0074] (6) The stacked cells are subjected to isostatic pressing at 200°C for 10 minutes at a pressure of 200MPa.

[0075] Example 2

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

[0077] (1) Preparation of the positive electrode sheet: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene, and lithium iron phosphate positive electrode material (80% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder) and Li6PS5Cl (16% by mass of dry powder) were added and stirred thoroughly to form a stable positive electrode material slurry. The slurry was then coated on both sides of an aluminum foil with a thickness of 12 μm, with a coating amount of 22 mg / cm². 2 After drying, the positive electrode sheet is rolled to obtain a thickness of 212μm. The size of the positive electrode sheet after cutting is 57×77mm. 2 ;

[0078] (2) Preparation of negative electrode sheet: Lithium metal is laminated onto copper foil to form a copper-lithium composite strip. The copper foil is 6μm thick, and the lithium metal layers on both sides are 20μm thick. The size of the negative electrode sheet after cutting is 60×80mm. 2 ;

[0079] (3) Preparation of solid electrolyte layer: LLZO oxide solid electrolyte, PEO, and lithium salt are dissolved in NMP. In the solid electrolyte layer, the content of oxide solid electrolyte is 40%, the content of PEO is 40%, and the content of lithium salt is 20%. The thickness is 50μm. The size of the solid electrolyte layer after cutting is 60×80mm. 2 ;

[0080] (4) Provide a hollow quadrilateral frame structure insulation layer: material is polyvinylidene fluoride, thickness is 1μm, tensile strength is 70MPa, elastic modulus is 0.2GPa, compressive strength is 15MPa, inner frame size after cutting: 42×62mm 2 Outer frame dimensions: 62×82mm 2 (Frame width 10mm).

[0081] (5) Coat the insulating frame with solvent-free epoxy adhesive and attach it to the single-sided electrolyte layer to form a composite solid electrolyte layer; stack the negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer and negative electrode in sequence (align the geometric centers of the positive electrode, solid electrolyte layer, negative electrode and insulating frame), and connect the insulating frame layer to the positive electrode to obtain the battery cell. The number of positive and negative electrode layers of the battery cell is 10 positive and 11 negative, with a designed capacity of 1.7Ah.

[0082] (6) The stacked cells are subjected to isostatic pressing at 30°C for 0.5 minutes at a pressure of 3MPa.

[0083] Example 3

[0084] The specific steps for preparing an all-solid-state battery are as follows:

[0085] (1) Preparation of the positive electrode sheet: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene, and lithium cobalt oxide positive electrode material (80% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder), and Li6PS5Cl (16% by mass of dry powder) were added and stirred thoroughly to form a stable positive electrode material slurry. This slurry was then coated on both sides of an aluminum foil with a thickness of 12 μm, with a coating amount of 20 mg / cm². 2 After drying, the positive electrode sheet is rolled to obtain a thickness of 155μm. The size of the positive electrode sheet after cutting is 57×77mm. 2 ;

[0086] (2) Preparation of the negative electrode sheet: The silicon suboxide negative electrode material (60% by mass of dry powder), Li6PS5Cl (36% by mass of dry powder), SEBS binder (2% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder), and xylene solvent were thoroughly stirred to form a uniform and stable negative electrode material slurry. This slurry was then coated onto both sides of a 6μm copper foil with a coating amount of 5 mg / cm². 2 After drying, a negative electrode sheet with a thickness of 86μm was obtained. The size of the negative electrode sheet after cutting is 60×80mm. 2 ;

[0087] (3) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a conventional solvent-free dry process using a 651-type sulfide solid electrolyte and polytetrafluoroethylene (PTFE). The solid electrolyte layer contained 99.0% 651-type sulfide solid electrolyte and 1% PTFE; its thickness was 50 μm, and the dimensions of the cut solid electrolyte layer were 60 × 80 mm. 2 ;

[0088] (4) Provide a hollow quadrilateral frame structure insulation layer: material: polyethylene-styrene copolymer, thickness: 20μm, tensile strength: 130MPa, elastic modulus: 0.5GPa, compressive strength: 10MPa, inner frame dimensions after cutting: 56.8×76.8mm2 Outer frame dimensions: 61×80mm 2 .

[0089] (5) The insulating frame layer is laminated onto one side of the solid electrolyte layer to obtain the composite solid electrolyte layer; the negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer and negative electrode are stacked in sequence (the geometric centers of the positive electrode, solid electrolyte layer, negative electrode and insulating frame are aligned), and the insulating frame layer is connected to the positive electrode to obtain the battery cell. The number of positive and negative electrode layers of the battery cell is 10 positive and 11 negative, and the designed capacity is 2Ah.

[0090] (6) The stacked cells are subjected to isostatic pressing at 80°C for 10 minutes at a pressure of 600MPa.

[0091] Example 4

[0092] The specific steps for preparing an all-solid-state battery are as follows:

[0093] (1) Preparation of the positive electrode sheet: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene solvent. Lithium-rich manganese-based solid solution LMO positive electrode material (70% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder), and Li6PS5Cl (26% by mass of dry powder) were added and stirred thoroughly to form a stable positive electrode slurry. This slurry was then coated onto both sides of a 12μm thick aluminum foil with a coating amount of 17.5 mg / cm². 2 After drying, the positive electrode sheet is rolled to obtain a thickness of 164μm. The size of the positive electrode sheet after cutting is 57×77mm. 2 ;

[0094] (2) Preparation of the negative electrode sheet: Silver-carbon lithium-free negative electrode material (80% dry powder by mass, where the carbon material in silver-carbon is carbon nanotubes and the silver is silver nanoparticles, with a silver-to-carbon mass ratio of 1:9), Li6PS5Cl (16% dry powder by mass), SEBS binder (2% dry powder by mass), VGCF conductive agent (2% dry powder by mass), and xylene solvent were thoroughly stirred to form a uniform and stable negative electrode material slurry. This slurry was then coated onto both sides of a 6μm copper foil with a coating amount of 5 mg / cm². 2 After drying, a negative electrode sheet with a thickness of 75μm was obtained. The size of the negative electrode sheet after cutting is 60×80mm. 2 ;

[0095] (3) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a conventional solvent-free dry process using a 651-type sulfide solid electrolyte and polytetrafluoroethylene (PTFE). The solid electrolyte layer contained 98% 651-type sulfide solid electrolyte and 2% PTFE; its thickness was 30 μm, and the dimensions of the cut solid electrolyte layer were 60 × 80 mm. 2 ;

[0096] (4) Provide a hollow quadrilateral frame structure with an insulating frame layer: material is polyimide, thickness is 4μm, tensile strength is 160MPa, elastic modulus is 1.5GPa, compressive strength is 30MPa, and inner frame dimensions after cutting are 55×75mm. 2 Outer frame dimensions: 61×80mm 2 .

[0097] (5) The insulating frame layer is laminated onto one side of the solid electrolyte layer to obtain the composite solid electrolyte layer; the negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer and negative electrode are stacked in sequence (the geometric centers of the positive electrode, solid electrolyte layer, negative electrode and insulating frame are aligned, and the insulating frame is in contact with the positive electrode), and the insulating frame layer is connected to the positive electrode to obtain the cell. The number of positive and negative electrode layers of the cell is 10 positive and 11 negative, and the design capacity is 2Ah.

[0098] (6) The stacked cells are subjected to isostatic pressing at 80°C for 10 minutes at a pressure of 600MPa.

[0099] Example 5

[0100] The specific steps for preparing an all-solid-state battery are as follows:

[0101] (1) Preparation of the positive electrode sheet: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene solvent, and lithium manganese iron phosphate positive electrode material (70% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder) and Li6PS5Cl (26% by mass of dry powder) were added and stirred thoroughly to form a stable positive electrode material slurry. The slurry was then coated on both sides of a 12μm thick aluminum foil with a coating amount of 23mg / cm. 2 After drying, the positive electrode sheet is rolled to obtain a thickness of 231 μm. The size of the positive electrode sheet after cutting is 57 × 77 mm. 2 ;

[0102] (2) Preparation of the negative electrode sheet: Nano-silicon negative electrode material (65% by mass of dry powder), Li6PS5Cl (30% by mass of dry powder), SEBS binder (3% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder), and xylene solvent were thoroughly stirred to form a uniform and stable negative electrode material slurry. This slurry was then coated onto both sides of a 6μm copper foil with a coating amount of 1.9 mg / cm². 2 After drying, a negative electrode sheet with a thickness of 40μm was obtained. The size of the negative electrode sheet after cutting is 60×80mm. 2 ;

[0103] (3) Preparation of the solid electrolyte layer: The solid electrolyte layer was prepared by a conventional solvent-free dry process using a 651-type sulfide solid electrolyte and polytetrafluoroethylene (PTFE). The solid electrolyte layer contained 96% 651-type sulfide solid electrolyte and 4% PTFE; its thickness was 40 μm, and the dimensions of the cut solid electrolyte layer were 60 × 80 mm. 2 ;

[0104] (4) Provide a hollow quadrilateral frame structure insulation layer: material aramid, thickness 10μm, tensile strength 100MPa, elastic modulus 0.5GPa, compressive strength 25MPa, inner frame dimensions after cutting: 55×75mm 2 Outer frame dimensions: 61×80mm 2 .

[0105] (5) The insulating frame layer is laminated onto one side of the solid electrolyte layer to obtain the composite solid electrolyte layer; the negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer and negative electrode are stacked in sequence (the geometric centers of the positive electrode, solid electrolyte layer, negative electrode and insulating frame are aligned, and the insulating frame is in contact with the positive electrode), and the insulating frame layer is connected to the positive electrode to obtain the battery cell. The number of positive and negative electrode layers of the battery cell is 10 positive and 11 negative, and the designed capacity is 2Ah.

[0106] (6) The stacked cells are subjected to isostatic pressing at 150°C for 10 minutes at a pressure of 1000MPa.

[0107] Example 6

[0108] The specific steps for preparing an all-solid-state battery are as follows:

[0109] (1) Preparation of the positive electrode sheet: The SEBS binder (2% by mass of dry powder) was completely dissolved in xylene, and the 9-series ternary positive electrode material (NCM90) (80% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder), and Li6PS5Cl (16% by mass of dry powder) were added and stirred thoroughly to form a stable positive electrode material slurry. This slurry was then coated on both sides of an aluminum foil with a thickness of 12 μm, with a coating amount of 18 mg / cm². 2 After drying, the positive electrode sheet is rolled to obtain a thickness of 150μm. The size of the positive electrode sheet after cutting is 57×77mm. 2 ;

[0110] (2) Preparation of the negative electrode: The silicon suboxide negative electrode material (60% by mass of dry powder), Li6PS5Cl (36% by mass of dry powder), SEBS binder (2% by mass of dry powder), VGCF conductive agent (2% by mass of dry powder) and xylene solvent are thoroughly stirred to form a uniform and stable negative electrode material slurry, which is then coated on both sides of a 6μm copper foil with a coating amount of 5mg / cm. 2After drying, a negative electrode sheet with a thickness of 86μm was obtained. The size of the negative electrode sheet after cutting is 60×80mm. 2 ;

[0111] (3) Preparation of the solid electrolyte layer: An electrolyte membrane was obtained by wet coating of 651 type sulfide solid electrolyte and SEBS. The solid electrolyte layer contained 98% 651 type sulfide solid electrolyte and 2% SEBS; its thickness was 50 μm, and the dimensions of the cut solid electrolyte layer were 60 × 80 mm. 2 ;

[0112] (4) Provide a hollow quadrilateral frame structure with an insulating frame layer: material is polyimide, thickness is 6μm, tensile strength is 200MPa, elastic modulus is 1.2GPa, compressive strength is 35MPa, and inner frame dimensions after cutting are 55×75mm. 2 Outer frame dimensions: 62×82mm 2 .

[0113] (5) The insulating frame layer is laminated onto one side of the solid electrolyte layer to obtain the composite solid electrolyte layer; the negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer and negative electrode are stacked in sequence (the geometric centers of the positive electrode, solid electrolyte layer, negative electrode and insulating frame are aligned, and the insulating frame is in contact with the positive electrode), and the insulating frame layer is connected to the positive electrode to obtain the battery cell. The number of positive and negative electrode layers of the battery cell is 10 positive and 11 negative, and the designed capacity is 2Ah.

[0114] (6) The stacked cells are subjected to isostatic pressing at 50°C for 10 minutes at a pressure of 400MPa.

[0115] Comparative Example 1

[0116] The difference from Example 1 is that no insulating frame layer is used.

[0117] Comparative Example 2

[0118] The difference from Example 2 is that the insulating frame material used is polyethylene oxide (PEO) with a tensile strength of 10 MPa, which is lower than the 20 MPa required by this invention.

[0119] Comparative Example 3

[0120] The difference from Example 3 is that the thickness of the insulating frame layer is 25 μm, which exceeds the 0.5-20 μm range specified in this invention.

[0121] Comparative Example 4

[0122] The difference from Example 4 is that the insulating frame layer is made of ordinary plastic PE with an elastic modulus of 0.05 GPa, which is lower than the 0.1 GPa required by the present invention.

[0123] Comparative Example 5

[0124] The difference from Example 3 is that the inner frame dimensions after cutting the insulating frame are 56.9 × 76.9 mm. 2 Outer frame dimensions: 57×77mm 2 .

[0125] Comparative Example 6

[0126] The difference from Example 3 is that the inner frame size after cutting the insulating frame is 57×77mm. 2 Outer frame dimensions: 59×79mm 2 .

[0127] Comparative Example 7

[0128] The difference from Example 3 is that the inner frame dimensions after cutting the insulating frame are 56.9 × 76.9 mm. 2 Outer frame dimensions: 58×77mm 2 .

[0129] test:

[0130] 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.

[0131] Table 1

[0132]

[0133]

[0134] 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. An insulating frame layer is provided between the positive electrode and the negative electrode. The insulating frame layer is a hollow quadrilateral frame structure. The inner frame size of the quadrilateral frame is smaller than the size of the positive electrode, and the outer frame size is larger than the size of the positive electrode. The thickness of the insulating frame layer is 0.5 to 20 μm. The insulating frame layer is made of one or more of the following materials: polytetrafluoroethylene and its copolymers, polyvinylidene fluoride and its copolymers, polyethylene and its copolymers, polypropylene and its copolymers, polyimide, polyetherimide, aramid, PET, and PEEK. The insulating frame layer has a tensile strength ≥20MPa, an elastic modulus ≥0.1GPa, and a compressive strength ≥10MPa. After stacking and pressurizing, the insulating frame layer is embedded or partially embedded in the adjacent solid electrolyte layer.

2. The all-solid-state battery according to claim 1, characterized in that, The insulating frame layer is entirely located between the positive electrode plate and the solid electrolyte layer.

3. The all-solid-state battery according to claim 1, characterized in that, The insulating frame layer is alternately located between the positive electrode and the solid electrolyte layer, and between the negative electrode and the solid electrolyte layer.

4. The all-solid-state battery according to claim 1, characterized in that, The outer frame dimension of the quadrilateral frame of the insulating frame layer is greater than or equal to the dimension of the negative electrode sheet.

5. The all-solid-state battery according to claim 1, characterized in that, The difference between the outer frame size and the inner frame size of the quadrilateral frame of the insulating frame layer is 0.5-20mm.

6. The all-solid-state battery according to any one of claims 1-5, characterized in that, 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. 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 one of the following methods: Method 1: A solid electrolyte layer is provided; a negative electrode material slurry is coated on both sides of the negative electrode current collector and dried to obtain a negative electrode sheet; a positive electrode material slurry is coated on both sides of the positive electrode current collector and dried to obtain a positive electrode sheet; the solid electrolyte layer is cut to make the size of the solid electrolyte layer equal to the size of the negative electrode sheet, and the size of the positive electrode sheet is smaller than the size of the negative electrode sheet; A hollow quadrilateral frame structure insulating frame layer is provided. The inner frame size of the 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. The thickness of the insulating frame layer is 0.5 to 20 μm. The insulating frame layer is composited on the four edges of the solid electrolyte layer to obtain a composite solid electrolyte layer. The negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer, and negative electrode are stacked in sequence, with the insulating frame layer connected to the positive electrode to obtain the battery cell. The battery cells are subjected to pressure treatment; Method 2: A solid electrolyte layer is provided; a negative electrode material slurry is coated on both sides of the negative electrode current collector and dried to obtain a negative electrode sheet; a positive electrode material slurry is coated on both sides of the positive electrode current collector and dried to obtain a positive electrode sheet; the solid electrolyte layer is cut to make the size of the solid electrolyte layer equal to the size of the negative electrode sheet, and the size of the positive electrode sheet is smaller than the size of the negative electrode sheet; A hollow quadrilateral frame structure insulating frame layer is provided. The inner frame size of the 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. The thickness of the insulating frame layer is 0.5 to 20 μm. The insulating frame layer is composited on the four edges of the solid electrolyte layer to obtain a composite solid electrolyte layer. The cells are formed by stacking the negative electrode, composite solid electrolyte layer, positive electrode, composite solid electrolyte layer, and negative electrode in sequence, with the insulating frame layer alternately connected to the positive and negative electrode. The battery cells are subjected to pressure treatment.

10. The preparation method according to claim 9, characterized in that, The pressing 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 pressure is 3–1000MPa.

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