Dry electrode sheets containing solid electrolytes, their preparation methods and applications

Abstract

This invention discloses a dry-process electrode sheet containing a solid electrolyte, its preparation method, and its application. A sulfide solid electrolyte is incorporated into the positive electrode active layer, and a composite binder of polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR) is used. Unlike traditional dry-process electrode sheet preparation methods, this application eliminates the need for coating the current collector surface with an adhesive layer or adding other additives, thus avoiding the adverse effects of additional adhesive layers or additives on the conductivity of the positive electrode active layer. Simultaneously, this application uses a composite binder of PTFE and SBR to construct a three-dimensional network of adsorption between the positive electrode active material and PTFE, adsorption between PTFE and SBR, and adsorption between SBR and the positive electrode current collector. This improves the adhesion between the positive electrode active layer and the positive electrode current collector, thereby increasing the electron transport speed within the electrode sheet and reducing the internal resistance of the dry-process electrode sheet. Furthermore, the spraying, heating softening, and rolling processes of this application are all continuous processes, enabling continuous industrial production.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, specifically to a dry electrode sheet containing a solid electrolyte, its preparation method, and its application. Background Technology

[0002] Compared to liquid lithium-ion batteries, all-solid-state batteries offer superior safety performance due to their use of solid-state electrolytes. There are many types of solid-state electrolytes, among which sulfide solid-state electrolytes possess advantages such as strong ionic conductivity, good safety performance, good thermal stability, and a wide electrochemical stability window, making them an important research direction for solid-state battery electrolytes.

[0003] Traditional lithium-ion battery electrode sheets are coated using a wet coating method, which involves dissolving the conductive agent, active material, and binder in an organic solvent. However, sulfide solid electrolytes are unstable in most solvents, resulting in a decrease in their ionic conductivity.

[0004] Due to the instability of sulfide solid electrolytes with solvents, solvents cannot be used when sulfides are used as electrolytes. However, in dry processes for electrode fabrication without solvents, there is a problem of poor interfacial adhesion between the active material and the current collector. Methods to increase adhesion include coating the current collector surface with an adhesive layer or adding other additives; however, this affects the interfacial contact between the active material and the current collector, thus hindering electron transport within the cell, increasing internal resistance, and affecting the cell's cycle life. Summary of the Invention

[0005] In view of the above-mentioned problems in the prior art, the purpose of the present invention is to provide a dry electrode sheet containing solid electrolyte, its preparation method and application. The dry electrode sheet containing solid electrolyte can significantly enhance the adhesion between the positive current collector and the positive active layer attached to the positive current collector without coating with a glue layer or adding other additives.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A dry-process electrode sheet containing a solid electrolyte includes a positive current collector and a positive active layer attached to the positive current collector. The positive active layer includes a positive active material, a sulfide solid electrolyte, a conductive agent, and a composite binder. The composite binder is polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR).

[0008] In one embodiment, the sulfide solid electrolyte includes one or more of Li2S-P2S5, Li2S-SiS2, and Li2S-B2S3.

[0009] In one embodiment, the positive current collector comprises aluminum foil.

[0010] In one embodiment, the positive electrode active material is one or more of LiCoO2, NCM (811) and NCA.

[0011] In one embodiment, the conductive agent includes one or more of conductive carbon black, conductive graphite, superconducting carbon black, acetylene black, Ketjen black, carbon nanotubes, nanofibers (VGCF), and graphene.

[0012] In one embodiment, the powder comprises a positive electrode active material, a solid electrolyte, a conductive agent, and a composite binder in a mass ratio of (60–93):(20–5):(10–1):(10–1). The composite binder comprises polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR) in a mass ratio of (1–5):1.

[0013] This invention also provides a method for preparing a dry electrode sheet containing a solid electrolyte, comprising the following steps:

[0014] The positive electrode active material, sulfide solid electrolyte, conductive agent and composite binder are mixed and ball-milled to prepare the powder.

[0015] The powder is sprayed onto the surface of the positive electrode current collector to prepare a powder-sprayed positive electrode sheet;

[0016] The positive electrode sheet coated with the powder is heated, softened, and rolled to prepare the positive electrode and solid electrolyte composite component.

[0017] In one embodiment, during the mixing and ball milling process, the mass ratio of the total mass of the milling beads to the positive electrode active material, the sulfide solid electrolyte, the conductive agent and the composite binder is (5-20):(0.5-3).

[0018] In one embodiment, the process parameters for powder spraying are: electrostatic voltage 50–100 kV, compressed argon pressure 4–8 kg / cm². 2 The electrostatic current is 10-20 μA, the powder flow rate and pressure are 0.2-0.8 MPa, the atomization pressure is 0.2-0.7 MPa, and the distance between the positive electrode current collector and the powder is 20-50 mm.

[0019] In one embodiment, the temperature at which the powder-coated positive electrode sheet is heated and softened is 150–250°C.

[0020] The present invention also provides a full battery, the full battery comprising a dry electrode sheet containing a solid electrolyte as described in any of the above embodiments, and a negative electrode sheet stacked on the surface of the solid electrolyte.

[0021] The present invention also provides an electrical device comprising a dry electrode sheet containing a solid electrolyte as described in any of the above embodiments or a full battery as described in any of the above embodiments.

[0022] Compared with existing technologies, the present invention has the following beneficial effects:

[0023] This invention provides a dry-process electrode sheet containing a solid electrolyte. A solid sulfide electrolyte is incorporated into the positive electrode active layer, and a composite binder is used. The composite binder is composed of polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR). Unlike traditional dry-process electrode sheet preparation methods, this application eliminates the need to coat the current collector surface with an adhesive layer or add other additives, thus avoiding the adverse effects of additional adhesive layers or additives on the conductivity of the positive electrode active layer. Furthermore, this application uses the composite binder of PTFE and SBR to construct a three-dimensional network of adsorption between the positive electrode active material and PTFE, adsorption between PTFE and SBR, and adsorption between SBR and the positive electrode current collector. This improves the adhesion between the positive electrode active layer and the positive electrode current collector, thereby increasing the electron transport speed within the electrode sheet and reducing the internal resistance of the dry-process electrode sheet. Detailed Implementation

[0024] The following detailed description, in conjunction with specific embodiments, illustrates the dry-process electrode sheet containing solid electrolyte and the method for preparing the dry-process electrode sheet containing solid electrolyte of the present invention. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] This invention provides a dry-process electrode sheet containing a solid electrolyte. The composite dry electrode includes a positive current collector and a positive active layer attached to the positive current collector. The positive active layer includes a positive active material, a sulfide solid electrolyte, a conductive agent, and a composite binder. The composite binder is polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR). By selecting PTFE and SBR as binders, the two binders can be effectively bonded together. PTFE can adsorb the positive active material onto the polymer network, while SBR can effectively bond with the positive current collector, thereby enhancing the adhesion between the positive active layer and the positive current collector.

[0027] In one example, no solvent, especially an organic solvent, is used in the preparation of the dry electrode sheet containing the solid electrolyte.

[0028] In one example, the dry electrode sheet containing a solid electrolyte does not include an adhesive layer.

[0029] In one example, the dry electrode sheet containing solid electrolyte does not include polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl ethylene carbonate, polycarbonate, polyamide resin, methyl acrylate, ethyl acrylate, methyl 2-methacrylate, ethyl 2-methacrylate, polyphenylene ether, or other additives.

[0030] In one example, the sulfide solid electrolyte includes one or more of Li2S-P2S5, Li2S-SiS2, and Li2S-B2S3.

[0031] In one example, the current collector comprises aluminum foil.

[0032] In one example, the aluminum foil is 12 μm thick.

[0033] In one example, the conductive agent includes one or more of conductive carbon black, conductive graphite, superconducting carbon black, acetylene black, Ketjen black, carbon nanotubes, nanofibers (VGCF), and graphene.

[0034] In one example, the positive electrode active material includes a ternary material, which includes one or more of LiCoO2, NCM (811) and NCA.

[0035] In one example, the powder comprises a positive electrode active material, a solid electrolyte, a conductive agent, and a composite binder in a mass ratio of (60–93):(20–5):(10–1):(10–1). Specifically, the mass ratio of the positive electrode active material, solid electrolyte, conductive agent, and composite binder in the powder includes, but is not limited to, 60:20:10:10, 61:19:10:10, 70:10:10:10, 80:10:5:5, 84:11:2:3, 85:10:2:3, 86:9:2:3, 92:3:3:2, or 93:5:1:1.

[0036] In one example, the mass ratio of polytetrafluoroethylene (PTFE) to styrene-butadiene rubber (SBR) in the composite adhesive is (1–5):1. Specifically, the mass ratio of PTFE to SBR in the composite adhesive includes, but is not limited to, 2:1, 3:1, 4:1, 5:1, or 1:1. By mixing the two adhesives, a three-dimensional network can be constructed, consisting of adsorption by the active material and PTFE, adsorption by PTFE and SBR, and adsorption by SBR and aluminum foil, thereby enhancing the adhesion between the current collector and the active material.

[0037] This invention also provides a method for preparing a dry electrode sheet containing a solid electrolyte, comprising the following steps:

[0038] The positive electrode active material, sulfide solid electrolyte, conductive agent and composite binder are mixed and ball-milled to prepare the powder.

[0039] The powder is sprayed onto the surface of the positive electrode current collector to prepare a powder-sprayed positive electrode sheet;

[0040] The positive electrode sheet coated with the powder is heated, softened, and rolled to prepare the dry electrode sheet containing solid electrolyte.

[0041] In one example, the powder is sprayed onto both sides of the positive current collector to prepare a positive electrode sheet with powder spraying on both sides.

[0042] In one example, during the ball milling process, the mass ratio of the grinding balls to the total mass of the positive electrode active material, sulfide solid electrolyte, conductive agent, and composite binder is (20–5):(0.5–3). Specifically, the mass ratio of the grinding balls to the total mass of the positive electrode active material, sulfide solid electrolyte, conductive agent, and composite binder includes, but is not limited to, 20:0.5, 20:3, 19:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, or 5:1.

[0043] In one example, the ball milling process includes large balls and small balls with a mass ratio of (1-10):1 and a diameter ratio of (2-4):1. Specifically, the mass ratio of large balls to small balls includes, but is not limited to, 10:1, 9:1, 8:1, 5:1, 4:1:3:1, 2:1, or 1:1, and the diameter ratio of large balls includes, but is not limited to, 2:1, 3:1, or 4:1.

[0044] In one example, the rotational speed during the ball milling process is (200-500) r / min. Specifically, the rotational speed during the ball milling process includes, but is not limited to, 200 r / min, 210 r / min, 220 r / min, 250 r / min, 300 r / min, 310 r / min, 320 r / min, 350 r / min, 360 r / min, 390 r / min, 400 r / min, 450 r / min, 480 r / min, 490 r / min, or 500 r / min.

[0045] In one example, the ball milling time during the mixing process is (30-100 min). Specifically, the ball milling time includes, but is not limited to, 30 min, 31 min, 32 min, 39 min, 40 min, 41 min, 49 min, 50 min, 55 min, 59 min, 60 min, 61 min, 69 min, 70 min, 80 min, 90 min, 99 min, or 100 min.

[0046] In one example, the process parameters for powder spraying are: electrostatic voltage 50–100 kV, compressed argon pressure 4–8 kg / cm². 2 The electrostatic current is 10–20 μA, the powder flow rate and pressure are 0.2–0.8 MPa, the atomization pressure is 0.2–0.7 MPa, and the distance between the positive current collector and the powder is 20–50 mm. Specifically, the electrostatic voltage includes, but is not limited to, 50 kV, 51 kV, 55 kV, 59 kV, 60 kV, 65 kV, 69 kV, 70 kV, 75 kV, 79 kV, 80 kV, 85 kV, 89 kV, 90 kV, 95 kV, or 100 kV, and the compressed argon pressure includes, but is not limited to, 4 kg / cm³. 2 4.1 kg / cm 2 4.5kg / cm 2 4.9kg / cm 2 5kg / cm 2 5.5kg / cm 2 5.9 kg / cm 2 6kg / cm 2 6.1 kg / cm 2 6.4 kg / cm 2 6.5kg / cm 2 6.6 kg / cm 2 6.7 kg / cm 2 6.8kg / cm 2 6.9 kg / cm 2 7kg / cm 2 7.5kg / cm 2Or 8kg / cm 2 The electrostatic current includes, but is not limited to, 10μA, 11μA, 12μA, 15μA, 16μA, 17μA, 18μA, 19μA, or 20μA; the powder flow rate pressure includes, but is not limited to, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, or 0.8MPa; the atomization pressure includes, but is not limited to, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, or 0.7MPa; and the distance between the positive current collector and the powder includes, but is not limited to, 20mm, 21mm, 22mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, 35mm, 36mm, 38mm, 39mm, 40mm, 41mm, 45mm, 48mm, 59mm, or 50mm.

[0047] In one example, the coating density of the positive electrode sheet coated with the powder is 400–500 g / m². 2 Specifically, the coating density of the positive electrode sheet coated with the powder includes, but is not limited to, 400 g / m². 2 401g / m 2 402g / m 2 410g / m 2 420g / m 2 440g / m 2 441g / m 2 442g / m 2 443g / m 2 450g / m 2 460g / m 2 470g / m 2 480g / m 2 490g / m 2 Or 500g / m 2 .

[0048] In one example, the temperature at which the powder-coated positive electrode sheet is heated and softened is 150–250°C. Specifically, the temperature at which the powder-coated positive electrode sheet is heated and softened includes, but is not limited to, 150°C, 151°C, 159°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C.

[0049] In one example, during the compaction process, the compaction pressure is (50-130)T, and the compaction speed does not exceed 50m / min. Specifically, the compaction pressure includes, but is not limited to, 50T, 60T, 70T, 80T, 90T, 91T, 95T, 99T, 100T, 110T, 120T, 129T, or 130T, and the compaction speed includes, but is not limited to, 10m / min, 15m / min, 20m / min, 25m / min, 30m / min, 35m / min, 40m / min, 45m / min, or 50m / min.

[0050] The present invention also provides a full battery, the full battery comprising a dry electrode sheet containing a solid electrolyte as described in any of the above embodiments, and a negative electrode sheet stacked on the surface of the solid electrolyte.

[0051] The present invention also provides an electrical device comprising a dry electrode sheet containing a solid electrolyte as described in any of the above embodiments or a full battery as described in any of the above embodiments.

[0052] The following are specific embodiments. Unless otherwise specified, the raw materials used in the embodiments are all commercially available.

[0053] Example 1

[0054] This embodiment provides a dry-process electrode sheet containing Li2S-P2S5 solid electrolyte, and the preparation process is as follows:

[0055] (1) Preparation of powder with NCA: solid electrolyte: conductive agent: binder 1: binder 2 = 85:10:2:2:1

[0056] In an argon-dry atmosphere with a moisture content of less than 1 ppm and an oxygen content of less than 1 ppm, 1700 g of NCA, 200 g of Li₂S-P₂S₅ solid electrolyte, 40 g of graphene (conductive agent), 40 g of polytetrafluoroethylene (teffect 1), and 20 g of styrene-butadiene rubber (teffect 2) were weighed. The weighed NCA, Li₂S-P₂S₅ solid electrolyte, graphene, PTFE, and styrene-butadiene rubber were placed in a ball mill jar for ball milling. During the mixing and ball milling process, the mass ratio of milling beads to the total mass of the mixture was 10:1, the mass ratio of large balls to small balls was 2:1, the diameter ratio of large balls to small balls was 2:1, the rotation speed was set to 360 r / min, and the milling time was 60 min. After ball milling, powder was obtained.

[0057] (2) Preparation of dry electrode sheets containing Li2S-P2S5 solid electrolyte

[0058] In an argon-drying atmosphere with a moisture content below 1 ppm and an oxygen content below 1 ppm, aluminum foil is used as the substrate and hung on a reel. The powder from the first step is used as the target material, and powder is sprayed onto the surface of the aluminum foil using a spray gun. During the powder spraying process, the electrostatic voltage is set to 70 kV, and the compressed argon pressure is set to 6.5 kg / cm³. 2 The electrostatic current was set to 15 μA, the powder flow rate and pressure to 0.45 MPa, the atomization pressure to 0.40 MPa, and the distance between the spray gun nozzle and the aluminum foil to 40 mm. After completing the single-sided spraying of the aluminum foil, the second side of the aluminum foil was sprayed. The steps and parameter settings are as shown above, resulting in a double-sided powder-coated positive electrode sheet. The coating density of the prepared double-sided powder-coated positive electrode sheet is 442 g / cm³. 2 .

[0059] The obtained powder-coated positive electrode sheet was heated and softened in a high-temperature furnace at 200℃ for 5 minutes. By softening the polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR) at high temperature, NCA, graphene, and Li₂S-P₂S₅ solid electrolyte were adsorbed onto aluminum foil. After softening, the powder-coated positive electrode sheet was rolled to a thickness of 133±2 μm using a rolling process. The rolling pressure was set to 90T, and the rolling speed was 50 m / min. After rolling, a dry-process electrode sheet containing Li₂S-P₂S₅ solid electrolyte was obtained.

[0060] Finally, the prepared dry electrode sheet containing Li2S-P2S5 solid electrolyte is wound up.

[0061] Example 2

[0062] This embodiment provides a dry-process electrode sheet preparation method for a Li2S-SiS2 solid electrolyte, and the preparation process is as follows:

[0063] (1) Preparation of powder with NCA: solid electrolyte: conductive agent: binder 1: binder 2 = 85:10:2:2:1

[0064] In an argon-dry atmosphere with a moisture content of less than 1 ppm and an oxygen content of less than 1 ppm, 1700 g of NCA, 200 g of Li₂S-SiS₂ solid electrolyte, 40 g of graphene (conductive agent), 40 g of polytetrafluoroethylene (PTFE) (binder 1), and 20 g of styrene-butadiene rubber (binder 2) were weighed. The weighed NCA, Li₂S-SiS₂ solid electrolyte, graphene, PTFE, and styrene-butadiene rubber were placed in a ball mill jar for ball milling. During the mixing and ball milling process, the mass ratio of milling beads to the total mass of the mixture was 10:1, the mass ratio of large balls to small balls was 2:1, the diameter ratio of large balls to small balls was 2:1, the rotation speed was set to 360 r / min, and the milling time was 60 min. After ball milling, powder was obtained.

[0065] (2) Preparation of dry electrode sheets containing Li2S-SiS2 solid electrolyte

[0066] In an argon-drying atmosphere with a moisture content below 1 ppm and an oxygen content below 1 ppm, aluminum foil is used as the substrate and hung on a reel. The powder from the first step is used as the target material, and powder is sprayed onto the surface of the aluminum foil using a spray gun. During the powder spraying process, the electrostatic voltage is set to 70 kV, and the compressed argon pressure is set to 6.5 kg / cm³. 2 The electrostatic current was set to 15 μA, the powder flow rate and pressure to 0.45 MPa, the atomization pressure to 0.40 MPa, and the distance between the spray gun nozzle and the aluminum foil to 40 mm. After completing the single-sided spraying of the aluminum foil, the second side of the aluminum foil was sprayed. The steps and parameter settings are as shown above, resulting in a double-sided powder-coated positive electrode sheet. The coating density of the prepared double-sided powder-coated positive electrode sheet is 442 g / cm³. 2 .

[0067] The obtained powder-coated positive electrode sheet was heated and softened in a high-temperature furnace at 200℃ for 5 minutes. By softening the polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR) at high temperature, NCA, graphene, and Li₂S-SiS₂ solid electrolyte were adsorbed onto the aluminum foil. After softening, the powder-coated positive electrode sheet was rolled to a thickness of 133±2 μm using a rolling process. The rolling pressure was set to 90T, and the rolling speed was 50 m / min. After rolling, a dry-process electrode sheet containing Li₂S-SiS₂ solid electrolyte was obtained.

[0068] Finally, the prepared dry electrode sheet containing Li2S-SiS2 solid electrolyte is wound up.

[0069] Example 3

[0070] This embodiment provides a dry-process electrode sheet containing Li2S-B2S3 solid electrolyte, and the preparation process is as follows:

[0071] (1) Preparation of powder with NCA: solid electrolyte: conductive agent: binder 1: binder 2 = 85:10:2:2:1

[0072] In an argon-dry atmosphere with a moisture content of less than 1 ppm and an oxygen content of less than 1 ppm, 1700 g of NCA, 200 g of Li₂S-B₂S₃ solid electrolyte, 40 g of graphene (conductive agent), 40 g of polytetrafluoroethylene (PTFE) (binder 1), and 20 g of styrene-butadiene rubber (binder 2) were weighed. The weighed NCA, Li₂S-B₂S₃ solid electrolyte, graphene, PTFE, and styrene-butadiene rubber were placed in a ball mill jar for ball milling. During the mixing and ball milling process, the mass ratio of milling beads to the total mass of the mixture was 10:1, the mass ratio of large balls to small balls was 2:1, the diameter ratio of large balls to small balls was 2:1, the rotation speed was set to 360 r / min, and the milling time was 60 min. After ball milling, powder was obtained.

[0073] (2) Preparation of dry electrode sheets containing Li2S-B2S3 solid electrolyte

[0074] In an argon-drying atmosphere with a moisture content below 1 ppm and an oxygen content below 1 ppm, aluminum foil is used as the substrate and hung on a reel. The powder from the first step is used as the target material, and powder is sprayed onto the surface of the aluminum foil using a spray gun. During the powder spraying process, the electrostatic voltage is set to 70 kV, and the compressed argon pressure is set to 6.5 kg / cm³. 2 The electrostatic current was set to 15 μA, the powder flow rate and pressure to 0.45 MPa, the atomization pressure to 0.40 MPa, and the distance between the spray gun nozzle and the aluminum foil to 40 mm. After completing the single-sided spraying of the aluminum foil, the second side of the aluminum foil was sprayed. The steps and parameter settings are as shown above, resulting in a double-sided powder-coated positive electrode sheet. The coating density of the prepared double-sided powder-coated positive electrode sheet is 442 g / cm³. 2 .

[0075] The obtained powder-coated positive electrode sheet was heated and softened in a high-temperature furnace at 200℃ for 5 minutes. By softening the polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR) at high temperature, NCA, graphene, and Li₂S-B₂S₃ solid electrolyte were adsorbed onto aluminum foil. After softening, the powder-coated positive electrode sheet was rolled to a thickness of 133±2 μm using a rolling process. The rolling pressure was set to 90T, and the rolling speed was 50 m / min. After rolling, a dry-process electrode sheet containing Li₂S-B₂S₃ solid electrolyte was obtained.

[0076] Finally, the prepared dry electrode sheet containing Li2S-B2S3 solid electrolyte is wound up.

[0077] Comparative Example 1

[0078] This embodiment provides a method for preparing a dry electrode sheet containing a solid electrolyte. The preparation process is the same as in Embodiment 1, except that the dry electrode sheet containing a solid electrolyte contains only one binder, polytetrafluoroethylene.

[0079] (1) Preparation of powder of NCA: solid electrolyte: conductive agent: binder 1 = 85:10:2:2:3

[0080] In an argon-dry atmosphere with a moisture content of less than 1 ppm and an oxygen content of less than 1 ppm, 1700 g of NCA, 200 g of solid electrolyte Li₂S-P₂S₅, 40 g of graphene (conductive agent), and 60 g of polytetrafluoroethylene (binder 1) were weighed. The weighed NCA, Li₂S-P₂S₅, graphene, and polytetrafluoroethylene were placed in a ball mill jar for ball milling. During the mixing and ball milling process, the mass ratio of milling beads to the total mass of the mixture was 10:1, the mass ratio of large balls to small balls was 2:1, the diameter ratio of large balls to small balls was 2:1, the rotation speed was set to 360 r / min, and the milling time was 60 min. After ball milling, powder was obtained.

[0081] (2) Preparation of dry electrode sheets containing Li2S-P2S5 solid electrolyte

[0082] In an argon-drying atmosphere with a moisture content of less than 1 ppm and an oxygen content of less than 1 ppm, aluminum foil is used as the substrate and hung on an unwinding spool. The powder from the first step is used as the target material, and powder is sprayed onto the surface of the aluminum foil using a spray gun. During the powder spraying process, the electrostatic voltage is set to 70 kV, and the compressed argon pressure is set to 6.5 kg / cm³. 2 The electrostatic current was set to 15 μA, the powder flow rate and pressure to 0.45 MPa, the atomization pressure to 0.40 MPa, and the distance between the spray gun nozzle and the aluminum foil to 40 mm. After completing the single-sided spraying of the aluminum foil, the second side of the aluminum foil was sprayed. The steps and parameter settings are as shown above, resulting in a double-sided powder-coated positive electrode sheet. The coating density of the prepared double-sided powder-coated positive electrode sheet is 442 g / cm³. 2 .

[0083] The obtained powder-coated positive electrode sheet was heated and softened in a high-temperature furnace at 200℃ for 5 minutes. By softening the polytetrafluoroethylene (PTFE) at high temperature, NCA, graphene, and Li₂S-P₂S₅ solid electrolyte were adsorbed onto aluminum foil. After softening, the powder-coated positive electrode sheet was rolled to a thickness of 133±2 μm using a rolling process. During rolling, the rolling pressure was set to 90T, and the rolling speed was 50 m / min. After rolling, a dry-process electrode sheet containing Li₂S-P₂S₅ solid electrolyte was obtained.

[0084] Finally, the prepared dry electrode sheet containing Li2S-P2S5 solid electrolyte is wound up.

[0085] Comparative Example 2

[0086] This embodiment provides a method for preparing a dry electrode sheet containing a solid electrolyte. The preparation process is the same as in Embodiment 1, except that the dry electrode sheet containing a solid electrolyte contains only one type of binder, styrene-butadiene rubber.

[0087] (1) Preparation of powder of NCA: solid electrolyte: conductive agent: binder 2 = 85:10:2:3

[0088] In an argon-dry atmosphere with a moisture content of less than 1 ppm and an oxygen content of less than 1 ppm, 1700 g of NCA, 200 g of Li₂S-P₂S₅ solid electrolyte, 40 g of graphene, and 60 g of styrene-butadiene rubber (binder 2) were weighed. The weighed NCA, Li₂S-P₂S₅ solid electrolyte, graphene, and styrene-butadiene rubber were placed in a ball mill jar for ball milling. During the mixing and ball milling process, the mass ratio of milling beads to the total mass of the mixture was 10:1, the mass ratio of large balls to small balls was 2:1, the diameter ratio of large balls to small balls was 2:1, the rotation speed was set to 360 r / min, and the milling time was 60 min. After ball milling, powder was obtained.

[0089] (2) Preparation of dry electrode sheets containing Li2S-P2S5 solid electrolyte

[0090] In an argon-drying atmosphere with a moisture content of less than 1 ppm and an oxygen content of less than 1 ppm, aluminum foil is used as the substrate and hung on an unwinding spool. The powder from the first step is used as the target material, and powder is sprayed onto the surface of the aluminum foil using a spray gun. During the powder spraying process, the electrostatic voltage is set to 70 kV, and the compressed argon pressure is set to 6.5 kg / cm³. 2The electrostatic current was set to 15 μA, the powder flow rate and pressure to 0.45 MPa, the atomization pressure to 0.40 MPa, and the distance between the spray gun nozzle and the aluminum foil to 40 mm. After completing the single-sided spraying of the aluminum foil, the second side of the aluminum foil was sprayed. The steps and parameter settings are as shown above, resulting in a double-sided powder-coated positive electrode sheet. The coating density of the prepared double-sided powder-coated positive electrode sheet is 442 g / cm³. 2 .

[0091] The obtained powder-coated positive electrode sheet was heated and softened in a high-temperature furnace at 200℃ for 5 minutes. By softening the styrene-butadiene rubber at high temperature, NCA, graphene, and the solid electrolyte Li₂S-P₂S₅ were adsorbed onto the aluminum foil. After the powder-coated positive electrode sheet was softened, it was rolled to a thickness of 133±2 μm using a rolling process. During rolling, the rolling pressure was set to 90T and the rolling speed to 50 m / min. After rolling, a dry-process electrode sheet containing the solid electrolyte was obtained.

[0092] Finally, the prepared dry electrode sheet containing Li2S-P2S5 solid electrolyte is wound up.

[0093] The test results of the dry-process electrode sheets containing solid electrolytes in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 are as follows:

[0094] 1. Diaphragm resistance

[0095] Test instrument: diaphragm resistance meter, Hangzhou Chuanyuan Technology Co., Ltd., TT-ACCF-G1.

[0096] Test method: The electrode is punched into a circular piece with a diameter of 16mm. The circular piece is placed between the two poles of the film resistance meter, and the pressure between the poles is 0.6MPa.

[0097] The resistance test results of the dry-process electrode sheet containing solid electrolyte are as follows:

[0098]

[0099]

[0100] 2. Membrane adhesion

[0101] Testing instrument: Wenzhou Sanhe Measuring Instruments Co., Ltd. SBL-90 peel force tester.

[0102] Attach the bottom of the electrode to the workbench with double-sided tape, and attach transparent tape to the top side of the electrode. Clamp one end of the tape to a tension gauge, pull the tape off the tension gauge, and record the maximum tension.

[0103] The electrode adhesion results for dry-process electrode sheets containing solid electrolytes are as follows:

[0104]

[0105] The test results from Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 in the table show that the average resistance of the dry-process electrode sheet containing Li2S-P2S5 solid electrolyte obtained after heating and softening using polytetrafluoroethylene and styrene-butadiene rubber as binders is 0.46 Ω / cm. 2 The average adhesion force was 0.124 N / m; the average resistance of the dry-process electrode sheet containing Li2S-SiS2 solid electrolyte obtained after heating and softening using polytetrafluoroethylene and styrene-butadiene rubber as binders was 0.59 Ω / cm. 2 The average adhesion force was 0.119 N / m; the average resistance of the dry-process electrode sheet containing Li₂S-B₂S₃ solid electrolyte obtained after heating and softening using polytetrafluoroethylene and styrene-butadiene rubber as binders was 0.72 Ω / cm. 2 The average adhesion force was 0.123 N / m; the average resistance of the dry-process electrode sheet containing Li2S-P2S5 solid electrolyte obtained after heating and softening, using only polytetrafluoroethylene as a binder, was 0.57 Ω / cm. 2 The average adhesion force was 0.068 N / m; the average resistance of the dry-process electrode sheet containing Li2S-P2S5 solid electrolyte obtained after heating and softening, using only styrene-butadiene rubber as a binder, was 0.68 Ω / cm. 2 The average adhesion force was 0.086 N / m. The resistance and film adhesion tests of Example 1 and Comparative Examples 1 and 2 showed that, after heating and softening, the dry electrode sheet of the sulfide-containing solid electrolyte using the composite adhesive of polytetrafluoroethylene and styrene-butadiene rubber exhibited strong adhesion and the lowest resistance.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A full battery, characterized in that, The full cell includes a dry-process electrode sheet containing a solid electrolyte, and a separator and a negative electrode sheet sequentially stacked on the surface of the dry-process electrode sheet; The dry electrode sheet consists of a positive current collector and a positive active layer attached to the positive current collector. The positive active layer includes a positive active material, a sulfide solid electrolyte, a conductive agent, and a composite binder. The sulfide solid electrolyte includes Li2S-P2S5; The composite adhesive comprises polytetrafluoroethylene and styrene-butadiene rubber in a mass ratio of (1~5): 1:1; The preparation of the dry electrode sheet containing solid electrolyte includes the following steps: The positive electrode active material, sulfide solid electrolyte, conductive agent and composite binder are mixed and ball-milled to prepare powder; The powder is sprayed onto the surface of the positive electrode current collector to prepare a powder-sprayed positive electrode sheet; The positive electrode sheet coated with the powder is heated, softened, and rolled to prepare the dry-process electrode sheet containing solid electrolyte; the process parameters for powder coating include: electrostatic voltage 50~100 kV, compressed argon pressure 4~8 kg / cm². 2 The electrostatic current is 10~20 μA, the powder flow rate and pressure are 0.2~0.8 MPa, the atomization pressure is 0.2~0.7 MPa, and the distance between the positive electrode current collector and the powder is 20~50 mm. The temperature at which the positive electrode sheet coated with the powder softens upon heating is 150~250 ℃.

2. The full battery according to claim 1, characterized in that, The positive current collector includes aluminum foil.

3. The full battery according to claim 1, characterized in that, The positive electrode active material includes one or more of LiCoO2, NCM and NCA.

4. The full battery according to claim 1, characterized in that, The conductive agent includes one or more of conductive carbon black, conductive graphite, superconducting carbon black, acetylene black, Ketjen black, carbon nanotubes, VGCF nanofibers, and graphene.

5. The full battery according to any one of claims 1 to 4, characterized in that, The positive electrode active layer comprises a positive electrode active material, a sulfide solid electrolyte, a conductive agent, and a composite binder in a mass ratio of (60~93):(20~5):(10~1):(10~1).

6. The full battery according to claim 1, characterized in that, During the mixing and ball milling process, the mass ratio of the total mass of the milling balls to the positive electrode active material, sulfide solid electrolyte, conductive agent and composite binder is (5~20):(0.5~3).

7. The full battery according to claim 1, characterized in that, The ball milling process includes large balls and small balls with a mass ratio of (1~10):1, and the diameter ratio of the large balls to the small balls is (2~4):

1. And / or, the ball milling speed is (200~500) r / min.

8. The full battery according to any one of claims 1 to 4, 6, and 7, characterized in that, The dry electrode sheet containing solid electrolyte does not include the adhesive layer.

9. The full battery according to any one of claims 1 to 4, 6, and 7, characterized in that, The dry electrode sheet containing solid electrolyte does not include polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl ethylene carbonate, polycarbonate, polyamide resin, methyl acrylate, ethyl acrylate, methyl 2-methacrylate, ethyl 2-methacrylate, or polyphenylene ether.

10. An electrical device, characterized in that, Includes the full battery as described in any one of claims 1 to 9.

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