Interface-modified all-solid-state battery as well as preparation method and application thereof

Abstract

The invention relates to the technical field of solid-state batteries, and discloses an interface-modified all-solid-state battery and a preparation method and application thereof.The all-solid-state battery comprises a positive plate, a solid-state electrolyte layer and a negative plate, a first eutectic electrolyte layer is arranged between the positive plate and the solid-state electrolyte layer, and a second eutectic electrolyte layer is arranged between the solid-state electrolyte layer and the negative plate; the first eutectic electrolyte layer comprises a first eutectic electrolyte; wherein the first eutectic electrolyte is a product obtained by carrying out eutectic crystallization reaction on a first hydrogen bond donor and a first hydrogen bond acceptor. The all-solid-state battery has excellent electrochemical properties such as low electrochemical impedance, long cycle life and high capacity retention rate.

Description

Technical Field

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

[0002] Solid-state batteries have become a hot research and development area in the battery field due to their significant advantages such as high energy density and high safety. However, in the practical application of solid-state batteries, the contact problem between the electrode and the solid electrolyte electrode seriously affects battery performance and is a key technical problem that urgently needs to be solved. To solve the contact problem between the electrode and the solid electrolyte electrode, the common technical solution is to inject a certain amount of liquid electrolyte into the assembled solid-state battery as an interface modifier. However, this approach has several drawbacks: First, since both the electrodes and electrolyte membrane in an all-solid-state battery are solid-state, the driving force (capillary force) for electrolyte wetting is significantly reduced compared to liquid batteries. This makes it difficult for the electrolyte to fully wet the battery interior, easily leading to poor local wetting and affecting the overall performance and stability of the battery. Second, the injected electrolyte will contact both the positive and negative electrodes simultaneously. The electrolyte must meet the stability requirements of both electrodes at the same time. However, conventional carbonate electrolytes lack stability for common negative electrode materials such as graphite, silicon-based, and lithium metal, and are prone to forming a solid electrolyte interphase (SEI) film on the negative electrode surface. This increases the impedance of the all-solid-state battery and reduces the charge-discharge efficiency and cycle life. Third, conventional electrolytes generally have the characteristics of being volatile and flammable. Batteries using this interface modification approach pose safety hazards, limiting the application of all-solid-state batteries in scenarios with high safety requirements.

[0003] Therefore, the existing solutions for solving the contact problem between the electrode and the solid electrolyte electrode in all-solid-state batteries by injecting liquid electrolyte are clearly insufficient, and there is an urgent need to propose a more effective solution to improve the performance and safety of all-solid-state batteries. Summary of the Invention

[0004] The purpose of this invention is to overcome the contact problem between the electrode and the solid electrolyte electrode in existing all-solid-state batteries, and to provide an interface-modified all-solid-state battery, its preparation method and application. This interface-modified all-solid-state battery has excellent electrochemical performance, such as low electrochemical impedance, long cycle life and high capacity retention.

[0005] To achieve the above objectives, the present invention provides an all-solid-state battery, which includes a positive electrode, a solid electrolyte layer, and a negative electrode, wherein a first eutectic electrolyte layer is disposed between the positive electrode and the solid electrolyte layer, and the first eutectic electrolyte layer includes a first eutectic electrolyte.

[0006] A second aspect of this invention provides a method for preparing an all-solid-state battery, comprising the following steps: (1) One of slurry A and slurry B is coated on one side surface of the positive electrode sheet and dried to obtain the treated positive electrode sheet; the other slurry is coated on the side surface of the solid electrolyte layer opposite to the positive electrode sheet and dried to obtain the treated solid electrolyte layer. Slurry A contains a first hydrogen bond donor, and slurry B contains a first hydrogen bond acceptor; (2) The treated positive electrode, the treated solid electrolyte layer and the negative electrode are assembled and shaped, and then eutectic treatment is performed.

[0007] The beneficial effects obtained by the present invention through the above technical solution are as follows: This application achieves highly efficient improvement in solid-solid interface contact by coating one of the two components of a eutectic electrolyte onto the surfaces of the electrode and the corresponding electrolyte membrane, respectively, through a eutectic process. Compared to the traditional method of injecting liquid electrolyte, this application avoids problems such as uneven diffusion and poor local wetting caused by insufficient capillary forces in liquid electrolytes. It enables the eutectic electrolyte to be uniformly distributed between the electrode and the solid electrolyte electrode, thereby forming a stable and good interface contact, improving the ion transport efficiency inside the all-solid-state battery, and effectively enhancing the overall performance and stability of the battery.

[0008] In a further preferred embodiment, this application can modify the eutectic electrolyte with suitable materials for the two different interfaces: the positive electrode-solid electrolyte membrane and the negative electrode-solid electrolyte membrane. This overcomes the limitation that liquid electrolytes must simultaneously meet the stability requirements of both positive and negative electrodes. It avoids the problem of increased battery impedance caused by the formation of an SEI film due to incompatibility between the electrolyte and the negative electrode material, and can fully leverage the performance advantages of different electrode materials, optimizing the battery's charge-discharge efficiency and cycle life. Simultaneously, the solution provided by this invention significantly reduces battery safety hazards, providing a reliable guarantee for the widespread application of all-solid-state batteries in fields with stringent safety requirements, such as new energy vehicles and energy storage systems. Detailed Implementation

[0009] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0010] The first aspect of the present invention provides an all-solid-state battery, the all-solid-state battery comprising a positive electrode, a solid electrolyte layer and a negative electrode, wherein a first eutectic electrolyte layer is disposed between the positive electrode and the solid electrolyte layer, the first eutectic electrolyte layer comprising a first eutectic electrolyte.

[0011] In the all-solid-state battery provided by the present invention, a first eutectic electrolyte layer is provided between the positive electrode and the solid electrolyte layer, which can significantly improve the solid-solid interface contact problem between the positive electrode and the solid electrolyte layer, reduce the interface impedance, and further improve the battery capacity retention rate and cycle stability.

[0012] In the all-solid-state battery provided by this invention, the presence of eutectic electrolyte can be observed by scanning electron microscopy in the pores of the positive electrode, the interface between the positive electrode and the solid electrolyte layer, and between the solid electrolyte layer particles.

[0013] According to the present invention, preferably, a second eutectic electrolyte layer is further disposed between the negative electrode sheet and the solid electrolyte layer, the second eutectic electrolyte layer comprising a second eutectic electrolyte.

[0014] In the all-solid-state battery provided by this invention, a second eutectic electrolyte layer is disposed between the negative electrode and the solid electrolyte layer, achieving a similar effect to the first eutectic electrolyte layer disposed between the positive electrode and the solid electrolyte layer. Furthermore, by modifying the positive electrode-solid electrolyte layer and the negative electrode-solid electrolyte layer interfaces with different eutectic electrolytes, the problem of liquid electrolytes being incompatible with two different interfaces can be solved.

[0015] According to the present invention, the first eutectic electrolyte may be the same as or different from the second eutectic electrolyte.

[0016] According to the present invention, the first eutectic electrolyte and / or the second eutectic electrolyte are in a liquid state and / or a glassy state at 25±5°C.

[0017] In the all-solid-state battery provided by the present invention, when the first eutectic electrolyte and / or the second eutectic electrolyte are in a liquid state and / or a glassy state at 25±5℃, the solid-solid interface contact problem in the all-solid-state battery can be improved, the pores between solid electrolyte particles can be filled, the interface impedance can be reduced, and the internal microcracks caused by repeated expansion of the electrode during cycling can be repaired.

[0018] According to the present invention, the first eutectic electrolyte is the product obtained by a eutectic reaction of a first hydrogen bond donor and a first hydrogen bond acceptor.

[0019] The second eutectic electrolyte is the product obtained by co-crystallization reaction of the second hydrogen bond donor and the second hydrogen bond acceptor.

[0020] According to the present invention, the first hydrogen bond donor and the second hydrogen bond donor may be the same or different.

[0021] Preferably, the first hydrogen bond donor and the second hydrogen bond donor are selected from at least one of methylacetamide, dimethylacetamide, 1,1,3,3-tetramethylurea, acetamide, benzamide, trifluoroacetamide, urea, acrylamide, butyrolactam, valproic acid lactone, caprolactam, heptanolactam, adiponitrile, ethylene carbonate, propanesulfonate lactone, sulfolane, methyl sulfolane, dimethyl sulfate, diethyl sulfate, formamide, dimethyl sulfone, dimethylmalononitrile, tetramethylsuccinate, cyclobutene sulfone, dithiopyridine, ethylene carbonate, trifluoroacetamide, methyl carbamate, dimethylimidazole, methylurea, dimethylurea, succinate, and thiourea; more preferably, succinate and / or dimethyl sulfone.

[0022] According to the present invention, the first hydrogen bond acceptor and the second hydrogen bond acceptor may be the same or different.

[0023] Preferably, the first hydrogen bond acceptor and the second hydrogen bond acceptor are each selected from soluble lithium salts.

[0024] Preferably, the first hydrogen bond acceptor and the second hydrogen bond acceptor are selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(perfluoroethyl)sulfonylimide, lithium trifluoromethanesulfonyl n-perfluorobutylsulfonylimide, lithium fluorosulfonyl n-perfluorobutylsulfonylimide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalatoborate), and lithium nitrate; more preferably, lithium bis(trifluoromethanesulfonyl)imide and / or lithium bis(fluorosulfonyl)imide.

[0025] According to the present invention, in the first eutectic electrolyte layer, the molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is (2-30):1; more preferably (2-10):1, for example, it can be a specific molar ratio or any range between the two such as 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0026] According to the present invention, in the second eutectic electrolyte layer, the molar ratio of the second hydrogen bond donor to the second hydrogen bond acceptor is (2-30):1; more preferably (2-10):1, for example, it can be a specific molar ratio or any range between two such as 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0027] In the all-solid-state battery provided by the present invention, when the above-mentioned preferred range is met, it is beneficial to ensure good liquefaction during the battery hot pressing process to ensure good interface contact, and has good lithium-ion transport performance to ensure the rate performance of the cell.

[0028] According to the present invention, the first eutectic electrolyte layer and the second eutectic electrolyte layer each contain a binder. Based on the total amount of the first eutectic electrolyte layer and / or the second eutectic electrolyte layer, the content of the first eutectic electrolyte and / or the second eutectic electrolyte is 70-99 wt%, and the content of the binder is 1-30 wt%. Preferably, the content of the first eutectic electrolyte and / or the second eutectic electrolyte is 85-98 wt%, for example 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, and the content of the binder is 2%-15 wt%.

[0029] In the all-solid-state battery provided by the present invention, when the above-mentioned preferred range is met, good adhesion can be achieved, ensuring that the electrolyte components coated on the electrode surface will not fall off during normal production processes.

[0030] In this invention, the selection range of the adhesive is relatively wide, and any conventional adhesive material in the art can be used. Preferably, the adhesive is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (SEBS), nitrile rubber, hydrogenated nitrile rubber, polymethyl methacrylate, polymethyl methacrylate copolymer, polymethyl acrylate, polymethyl acrylate copolymer, polyacrylonitrile, polyurethane, polyvinyl alcohol, polyacrylic acid, polyacrylic acid copolymer, and lithium polyacrylate.

[0031] According to the present invention, preferably, the first eutectic electrolyte and / or the second eutectic electrolyte further contain a stabilizer.

[0032] In this invention, the stabilizer works synergistically with the first eutectic electrolyte and / or the second eutectic electrolyte to improve interfacial stability.

[0033] Preferably, the stabilizer is selected from one or more of alkyl thiol compounds, trimethylsilane compounds, trithiocyanuric acid, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), and bis(1,5-pentylene)thiuram tetrasulfide (DPTT). Preferably, the alkyl thiol compound is selected from at least one of dodecyl mercaptan, n-octyl mercaptan, and n-hexadecyl mercaptan. More preferably, the stabilizer is dodecyl mercaptan and / or trithiocyanuric acid.

[0034] Preferably, based on the total amount of the first eutectic electrolyte layer and / or the second eutectic electrolyte layer, the content of the stabilizer is 0.1-10 wt%, preferably 1-5 wt%, for example 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0035] According to the present invention, the positive electrode sheet includes a positive current collector and a positive active layer composited on the surface of the positive current collector.

[0036] Preferably, the positive electrode active layer includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a sulfide electrolyte.

[0037] In this invention, there is no particular limitation on the type of positive electrode conductive agent; conventional positive electrode conductive agents in the art can be used.

[0038] In this invention, the mass ratio of positive electrode active material, sulfide electrolyte, positive electrode binder and positive electrode conductive agent in the positive electrode active layer is 100: (20-70): (0.1-5): (1-10).

[0039] In the all-solid-state battery provided by the present invention, when the above-mentioned preferred range is met, it is beneficial to good lithium-ion transport between electrode materials and electrolyte, and to ensure the energy density of the cell.

[0040] Preferably, the areal density of the positive electrode sheet is 5-30 mg / cm³. 2 More preferably 12-22 mg / cm³ 2 For example, it can be 12 mg / cm³ 2 13 mg / cm 2 14 mg / cm 2 15 mg / cm 2 16 mg / cm 2 17 mg / cm 2 18 mg / cm 2 19 mg / cm 2 20 mg / cm 2 21 mg / cm 2 22mg / cm 2 , and any value in between.

[0041] In this invention, areal density refers to the mass of the positive electrode active layer per unit area.

[0042] In this invention, the method for testing the areal density is as follows: a positive electrode sheet and an aluminum foil with a diameter of 16 mm are punched out, and the weights of the two are weighed respectively. The mass of the positive electrode sheet is subtracted from the mass of the aluminum foil to obtain the mass of the positive electrode active material, and the corresponding areal density data is obtained by calculation.

[0043] In the all-solid-state battery provided by the present invention, when the surface density of the positive electrode meets the above-mentioned preferred range, good rate performance and energy density can be achieved simultaneously.

[0044] In this invention, the positive electrode active material is selected from at least one of lithium cobalt oxide materials, nickel-cobalt-manganese ternary materials, lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials.

[0045] In this invention, the sulfide electrolyte is selected from Li 7-a (M b P 1-b )SX a Li 10+c M 1+c P 2-c S 12 Li 21- e Si3M d P 3-d S 23 X e At least one of the following, X is selected from at least one of Cl, F, Br, I, OH, O, O2, N, M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, 0<a≤2, 0≤b≤1, -1≤c≤2, 0≤d≤3, 0≤e≤3; According to some preferred embodiments of the present invention, sulfide electrolytes Li₂S, P₂S₅, LiX, and MX (X is selected from at least one of Cl, F, Br, I, OH, O, O₂, and N; M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, and Sb) are used to prepare Li₂S, P₂S₅, LiX, and MX (X is selected from at least one of Cl, F, Br, I, OH, O, O₂, and N; M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, and Sb) 7-a (M b P 1-b )SX a (0 < a ≤ 2, 0 ≤ b ≤ 1).

[0046] According to some preferred embodiments of the present invention, sulfide electrolytes Li₂S, P₂S₅, GeS₂, MS, and LiX (X is selected from at least one of Cl, F, Br, I, OH, O, O₂, and N; M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, and Sb) are used to prepare Li₂S. 10+c M 1+c P 2-c S 12 (-1≤c≤2).

[0047] According to some preferred embodiments of the present invention, sulfide electrolytes Li₂S, P₂S₅, SiS₂, MS, and LiX (X is selected from at least one of Cl, F, Br, I, OH, O, O₂, and N; M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, and Sb) are used to prepare Li₂S. 21-e Si3M d P 3-d S23 X e (0≤d≤3,0≤e≤3).

[0048] According to the present invention, the solid electrolyte layer includes a support layer and a solid electrolyte membrane laminated on the support layer, wherein the solid electrolyte membrane includes a solid electrolyte material and an electrolyte layer binder.

[0049] In this invention, the content of the electrolyte layer binder is 1-30 parts by weight relative to 100 parts by weight of solid electrolyte material.

[0050] In this invention, the thickness of the solid electrolyte layer is 5-80 μm.

[0051] In this invention, the solid electrolyte material is selected from lithium thiophosphate, Li... 7-a (M b P 1-b )SX a Li 10+c M 1+c P 2- c S 12 Li 21-e Si3M d P 3-d S 23 X e At least one of the following, X is selected from at least one of Cl, F, Br, I, OH, O, O2, N, M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, 0 < a ≤ 2, 0 ≤ b ≤ 1, -1 ≤ c ≤ 2, 0 ≤ d ≤ 3, 0 ≤ e ≤ 3; more preferably, the sulfide electrolyte is LPSC.

[0052] According to the present invention, the negative electrode sheet includes a negative electrode active material, preferably, the negative electrode active material is selected from at least one of Li-In alloy, lithium metal, micron silicon, nano silicon carbon, nano silicon oxygen, and graphite.

[0053] A second aspect of this invention provides a method for preparing an all-solid-state battery, comprising the following steps: (1) One of slurry A and slurry B is coated on one side surface of the positive electrode sheet and dried to obtain the treated positive electrode sheet; the other slurry is coated on the side surface of the solid electrolyte layer opposite to the positive electrode sheet and dried to obtain the treated solid electrolyte layer. Slurry A contains a first hydrogen bond donor, and slurry B contains a first hydrogen bond acceptor; (2) The treated positive electrode, the treated solid electrolyte layer and the negative electrode are assembled and shaped, and then eutectic treatment is performed.

[0054] According to the preparation method provided by the present invention, one of the two components of the eutectic electrolyte is coated onto the surface of the positive electrode and the solid electrolyte layer, respectively. The eutectic treatment improves the solid-solid interface contact, and this method is less prone to uneven diffusion of the liquid electrolyte. The all-solid-state battery assembled using this method exhibits excellent electrochemical performance, including low impedance, high capacity retention, and high cycle stability.

[0055] According to the present invention, before step (2), the method further includes: coating one of slurry C and slurry D onto one side surface of the negative electrode sheet, and drying it to obtain the treated negative electrode sheet; coating the other slurry onto the side surface of the solid electrolyte layer opposite to the negative electrode sheet, and drying it to obtain the treated solid electrolyte layer; wherein, slurry C contains a second hydrogen bond donor and slurry D contains a second hydrogen bond acceptor. Then, the treated positive electrode, the treated solid electrolyte layer, and the treated negative electrode are assembled and shaped, and then subjected to eutectic treatment.

[0056] According to the preparation method provided by the present invention, coating the surfaces of the negative electrode and the solid electrolyte layer with one of the two components of the eutectic electrolyte can achieve a similar effect to coating the surfaces of the positive electrode and the solid electrolyte layer with the eutectic electrolyte. Furthermore, by modifying the interfaces of the positive electrode-solid electrolyte layer and the negative electrode-solid electrolyte layer with different eutectic electrolytes, the problem of the liquid electrolyte being incompatible with two different interfaces can be effectively solved.

[0057] According to the preparation method provided by the present invention, preferably, the first hydrogen bond donor and the second hydrogen bond donor are the same or different, and are respectively selected from at least one of methylacetamide, dimethylacetamide, 1,1,3,3-tetramethylurea, acetamide, benzamide, trifluoroacetamide, urea, acrylamide, butyrolactam, valproic acid lactone, caprolactam, heptanolactam, adiponitrile, ethylene carbonate, propanesulfonate lactone, sulfolane, methyl sulfolane, dimethyl sulfate, diethyl sulfate, formamide, dimethyl sulfone, dimethylmalononitrile, tetramethylsuccinate, cyclobutene sulfone, dithiopyridine, ethylene carbonate, trifluoroacetamide, methyl carbamate, dimethylimidazole, methylurea, dimethylurea, succinate, and thiourea; more preferably, succinate and / or dimethyl sulfone.

[0058] According to the preparation method provided by the present invention, preferably, the first hydrogen bond acceptor and the second hydrogen bond acceptor are the same or different, and are respectively selected from soluble lithium salts, preferably from at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(perfluoroethyl)sulfonylimide, lithium trifluoromethanesulfonyl n-perfluorobutylsulfonylimide, lithium fluorosulfonyl n-perfluorobutylsulfonylimide, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalateborate)borate, and lithium nitrate; more preferably, lithium bis(trifluoromethanesulfonyl)imide and / or lithium bis(fluorosulfonyl)imide.

[0059] In this invention, the molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is (2-30):1; more preferably (2-10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, and any value in between.

[0060] In this invention, the molar ratio of the second hydrogen bond donor to the second hydrogen bond acceptor is (2-30):1; more preferably (2-10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, and any value in between.

[0061] According to the preparation method provided by the present invention, when the above-mentioned preferred range is met, the hydrogen bond donor and the hydrogen bond acceptor can be fully liquefied after contact, avoiding excessive solid matter of hydrogen bond acceptor or hydrogen bond donor remaining after the reaction. In this invention, the coating amount of slurry A or slurry B results in an increase in the areal density of the treated positive electrode by 0.1-100 mg / cm³. 2 More preferably, 0.25-5 mg / cm³ 2 For example, it could be 0.25 mg / cm³. 2 0.3 mg / cm 2 0.4 mg / cm 2 0.5 mg / cm 2 0.8 mg / cm 2 1mg / cm 2 1.2 mg / cm 2 1.5 mg / cm 2 2mg / cm 2 3mg / cm 2 4mg / cm 2 5mg / cm 2 , and any value in between.

[0062] In this invention, the increase in areal density is obtained by subtracting the areal density of the blank positive electrode from the areal density of the coated positive electrode, and the increase only includes hydrogen bond donors / acceptors.

[0063] In this invention, the coating amount of slurry A or slurry B results in an increase in the density of the treated solid electrolyte layer by 0.1-100 mg / cm³. 2 More preferably, 0.25-5 mg / cm³ 2 For example, it could be 0.25 mg / cm³. 2 0.3 mg / cm 2 0.4 mg / cm 2 0.5 mg / cm 2 0.8 mg / cm 2 1mg / cm 2 1.2 mg / cm 2 1.5 mg / cm 2 2mg / cm 2 3mg / cm 2 4mg / cm 2 5mg / cm 2 And any value in between.

[0064] In this invention, the coating amount of slurry C or slurry D results in an increase in the areal density of the treated negative electrode by 0.1-100 mg / cm³. 2 More preferably, it is 0.25-5 mg / cm²; for example, it could be 0.25 mg / cm². 2 0.3 mg / cm 2 0.4 mg / cm 2 0.5 mg / cm 2 0.8 mg / cm 2 1mg / cm 2 1.2 mg / cm 2 1.5 mg / cm 2 2mg / cm 2 3mg / cm 2 4mg / cm 2 5mg / cm 2 And any value in between.

[0065] Preferably, the coating amount of slurry C or slurry D results in an increase in the density of the treated solid electrolyte layer of 0.1-100 mg / cm³. 2 More preferably, it is 0.25-5 mg / cm²; for example, it could be 0.25 mg / cm². 2 0.3 mg / cm 2 0.4 mg / cm 2 0.5 mg / cm 2 0.8 mg / cm 2 1mg / cm 2 1.2 mg / cm 21.5 mg / cm 2 2mg / cm 2 3mg / cm 2 4mg / cm 2 5mg / cm 2 And any value in between.

[0066] According to the preparation method provided by the present invention, when the areal density meets the above-mentioned preferred range, it is beneficial to ensure that the electrolyte can fully fill the pores inside the electrode and the electrolyte membrane while ensuring the battery energy density, thus ensuring a smooth ion transport pathway.

[0067] According to the present invention, slurry A contains a stabilizer.

[0068] In this invention, the aforementioned synergistic effect improves interface stability.

[0069] The stabilizer is selected from one or more of alkyl thiols, trimethylsilanes, trithiocyanuric acid, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), and bis(1,5-pentylene)thiuram tetrasulfide (DPTT). Preferably, the alkyl thiols are selected from at least one of dodecyl mercaptan, n-octyl mercaptan, and n-hexadecyl mercaptan. More preferably, the stabilizer is dodecyl mercaptan and / or trithiocyanuric acid.

[0070] According to the present invention, based on the total amount of slurry A, the content of stabilizer is 0.1-10 wt%, preferably 1-5 wt%; for example, it can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and any value in between.

[0071] According to the present invention, preferably, slurry B contains a stabilizer.

[0072] According to the present invention, preferably, the stabilizer is selected from one or more of alkyl thiol compounds, trimethylsilane compounds, trithiocyanuric acid, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), and bis(1,5-pentylene)thiuram tetrasulfide (DPTT); preferably, the alkyl thiol compound is selected from at least one of dodecyl mercaptan, n-octyl mercaptan, and n-hexadecyl mercaptan; more preferably, the stabilizer is dodecyl mercaptan and / or trithiocyanuric acid. According to the present invention, based on the total amount of slurry B, the content of stabilizer is 0.1-10 wt%, preferably 1-5 wt%; for example, it can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and any value in between.

[0073] According to the present invention, preferably, the slurry C contains a stabilizer.

[0074] According to the present invention, preferably, the stabilizer is selected from one or more of alkyl thiol compounds, trimethylsilane compounds, trithiocyanuric acid, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), and bis(1,5-pentylene)thiuram tetrasulfide (DPTT). Preferably, the alkyl thiol compound is selected from at least one of dodecyl mercaptan, n-octyl mercaptan, and n-hexadecyl mercaptan. More preferably, the stabilizer is dodecyl mercaptan and / or trithiocyanuric acid. Preferably, based on the total amount of slurry C, the stabilizer content is 0.1-10 wt%, preferably 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and any value in between.

[0075] According to the present invention, slurry D contains a stabilizer.

[0076] The stabilizer is selected from one or more of alkyl thiols, trimethylsilanes, trithiocyanuric acid, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), and bis(1,5-pentylene)thiuram tetrasulfide (DPTT). Preferably, the alkyl thiols are selected from at least one of dodecyl mercaptan, n-octyl mercaptan, and n-hexadecyl mercaptan. More preferably, the stabilizer is dodecyl mercaptan and / or trithiocyanuric acid. Preferably, based on the total amount of slurry D, the stabilizer content is 0.1-10 wt%, preferably 1-5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and any value in between.

[0077] In the preparation method provided by the present invention, the stabilizer is the same substance as the stabilizer described in the first aspect, and therefore has the same effect, which will not be repeated here.

[0078] According to the preparation method provided by the present invention, preferably, the slurry A, slurry B, slurry C and slurry D also contain a binder, and the content of the binder is 0.1-10 wt% based on the total amount of slurry.

[0079] The adhesive is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polymethyl methacrylate, polymethyl methacrylate copolymer, polymethyl acrylate, polymethyl acrylate copolymer, polyacrylonitrile, polyurethane, polyvinyl alcohol, polyacrylic acid, polyacrylic acid copolymer, and lithium polyacrylate.

[0080] The slurry A and slurry C also contain a first solvent, with the content of the first solvent being 20-80 wt% based on the total amount of the slurry.

[0081] In this invention, the first solvent is selected from at least one of toluene, xylene, ethylene glycol dimethyl ether (DME), and tetrahydrofuran.

[0082] In this invention, slurry B and slurry D each contain a second solvent, and the content of the second solvent is 20-80 wt% based on the total amount of slurry.

[0083] In this invention, the second solvent is selected from at least one of toluene, xylene, ethylene glycol dimethyl ether (DME), and tetrahydrofuran.

[0084] According to the preparation method provided by the present invention, preferably, the preparation method of the positive electrode sheet includes: coating a positive electrode active slurry onto the surface of a positive electrode current collector, and then drying it. The positive electrode active slurry includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a sulfide electrolyte.

[0085] In this invention, the mass ratio of positive electrode active material, sulfide electrolyte, positive electrode binder, and positive electrode conductive agent is 100:(20-70):(0.1-5):(1-10).

[0086] In this invention, the positive electrode active slurry also contains a solvent, and preferably, the solid content of the positive electrode active slurry is 40-80 wt%.

[0087] In the preparation method provided by this invention, the solid content of the positive electrode active slurry refers to the proportion of solid substances, including positive electrode active materials, sulfide electrolytes, positive electrode binders, and positive electrode conductive agents, in the total mass of the positive electrode active slurry.

[0088] In this invention, the areal density of the positive electrode sheet is 5-30 mg / cm³. 2 For example, it could be 5mg / cm 2 8mg / cm 2 10mg / cm 2 12mg / cm 2 15mg / cm 2 18mg / cm 2 20mg / cm 2 22mg / cm 2 25mg / cm 2 28mg / cm 2 30mg / cm 2 .

[0089] In the preparation method provided by this invention, the areal density of the positive electrode sheet refers to the mass of the positive electrode active slurry per unit area after drying.

[0090] In this invention, the positive electrode active material is selected from at least one of lithium cobalt oxide materials, nickel-cobalt-manganese ternary materials, lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials. In this invention, the sulfide electrolyte is selected from Li 7-a (M b P 1-b )SX a Li 10+c M 1+c P 2-c S 12 Li 21- e Si3M d P 3-d S 23 X e At least one of the following, X is selected from at least one of Cl, F, Br, I, OH, O, O2, N, M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, 0 < a ≤ 2, 0 ≤ b ≤ 1, -1 ≤ c ≤ 2, 0 ≤ d ≤ 3, 0 ≤ e ≤ 3; more preferably, the sulfide electrolyte is LPSC.

[0091] According to the preparation method provided by the present invention, preferably, the preparation method of the solid electrolyte layer includes: coating a solid electrolyte slurry on the surface of a support layer, and then drying and peeling it off; the solid electrolyte slurry includes a solid electrolyte material and an electrolyte layer binder.

[0092] In this invention, the content of the electrolyte layer binder is 1-30 parts by weight relative to 100 parts by weight of solid electrolyte material.

[0093] In this invention, the solid electrolyte slurry also contains a solvent, and preferably, the solid content of the solid electrolyte slurry is 30-80 wt%.

[0094] In this invention, the type of solvent for the solid electrolyte slurry is not particularly limited, and conventional electrolyte solvents in the art can be used.

[0095] In the preparation method provided by this invention, the solid content of the solid electrolyte slurry refers to the proportion of solid substances, including solid electrolyte materials and electrolyte layer binders, in the total mass of the solid electrolyte slurry.

[0096] In this invention, the solid electrolyte material is selected from lithium thiophosphate, Li... 7-a (M b P 1-b )SXa Li 10+c M 1+c P 2- c S 12 Li 21-e Si3M d P 3-d S 23 X e At least one of the following, X is selected from at least one of Cl, F, Br, I, OH, O, O2, N, M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, 0 < a ≤ 2, 0 ≤ b ≤ 1, -1 ≤ c ≤ 2, 0 ≤ d ≤ 3, 0 ≤ e ≤ 3; more preferably, the sulfide electrolyte is LPSC.

[0097] In this invention, the negative electrode sheet comprises a negative electrode active material. Preferably, the negative electrode active material is selected from at least one of Li-In alloy, metallic lithium, micron-sized silicon, nano-sized silicon-carbon, nano-sized silicon-oxygen, and graphite.

[0098] According to the preparation method provided by the present invention, in step (2), the molding pressure is 10-500 MPa.

[0099] Preferably, the conditions for the eutectic treatment include: a temperature of 35-100℃ and a time of 0.5-5h.

[0100] Preferably, the preparation method further includes: performing secondary molding on the eutectic battery, wherein the pressure of the secondary molding is 10-400 MPa; preferably 300-400 MPa.

[0101] According to the preparation method provided by the present invention, when the preparation process meets the above-mentioned preferred range, it ensures good interfacial contact between solid and solid interfaces inside the solid-state battery, sufficient liquefaction after contact between hydrogen bond donors and acceptors, and filling of pores, thus ensuring ion transport pathways.

[0102] The third aspect of this invention claims an all-solid-state battery prepared by the method of the second aspect.

[0103] The present invention will be described in detail below through embodiments.

[0104] In the following examples and comparative examples: Battery charging and discharging settings: The test was conducted using the NEWARE high-performance battery testing system; (1) Charged at a constant current of 0.1C to 4.2V, and then discharged at a constant current of 0.1C to 2.7V, for 2 cycles; (2) Charged at a constant current of 0.5C to 4.2V, and then discharged at a constant current of 0.5C to 2.7V; Repeat step (2) to perform a cycle charge and discharge test (battery nominal specific capacity 200mAh / g).

[0105] Li in the following embodiments The preparation process of In alloy includes: using indium foil and lithium foil of specific thickness, with a molar ratio of In:Li = 1:3, and under a pressure of 40 MPa, undergoing several rolling-folding cycles to finally prepare a lithium-indium alloy foil with a thickness of 50 micrometers.

[0106] Drug abbreviation (in English): SEBS: YH-602 (Yueyang Petrochemical); The chemical formula of the LPSC used in the following examples is Li6PS5Cl.

[0107] Example 1: Positive electrode slurry preparation: The positive electrode active material is NCM811 ternary material, the binder is vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer (55:25:20), the sulfide electrolyte is LPSC, and the conductive agent is vapor-grown carbon fiber (VGCF). The content of each component in the positive electrode slurry is: positive electrode active material: sulfide electrolyte: binder: conductive agent = 57:37:2:4, and the solid content of the slurry is 40wt%.

[0108] Positive electrode preparation: The prepared slurry is coated onto aluminum foil and dried. The dried electrode is then cold-pressed using a roller press at a pressure of 250 MPa. The resulting positive electrode has an areal density of 15 mg / cm³. 2 .

[0109] Positive electrode surface coating with succinic acid: A toluene solution containing succinic acid and dodecyl mercaptan (succinic acid content 20wt%, dodecyl mercaptan content 2wt%, binder (hydrogenated nitrile rubber, ZN35156), toluene 77wt%) is coated on the surface of the positive electrode. After drying, an electrode with a succinic acid-coated surface is obtained. The increase in areal density is controlled to be 0.2 mg / cm² by adjusting the doctor blade thickness and coating speed. 2 .

[0110] Electrolyte membrane preparation: Under an inert gas atmosphere, 100 parts by weight of Li6PS5Cl (LPSC) solid electrolyte material was mixed with 1 part by weight of SEBS binder YH-602, and then heptane was added to adjust the solid content to 40 wt%. The slurry for forming the solid electrolyte layer was coated on aluminum foil, dried, and then peeled off to obtain a solid electrolyte layer with a thickness of 50 micrometers.

[0111] Electrolyte membrane surface coating: A 20 wt% LiTFSI DME solution was prepared and dissolved evenly. Then, 1 wt% binder (hydrogenated nitrile rubber, Zetpol® 2010H) was added and dissolved evenly. This binder was then coated onto the surface of the prepared solid electrolyte membrane. After solvent evaporation and drying, an electrolyte membrane with lithium salt coated on one side was obtained. The increase in areal density was controlled to be 0.1 mg / cm² by adjusting the doctor blade thickness and coating speed. 2 .

[0112] The molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is 7:1.

[0113] The negative electrode uses Li In alloy.

[0114] Positive electrode, solid electrolyte membrane, Li In alloy sheets are stamped into 10mm diameter discs. The surface of the resulting positive electrode is then bonded to the LiTFSI-coated surface of a solid electrolyte membrane. The uncoated surface of the solid electrolyte membrane and the Li... In alloy sheets were contacted and assembled into a molded battery. The battery was pressed under 300 MPa pressure, then heated to 70°C and held at that temperature for 3 hours. After cooling to room temperature, it was pressed again under 300 MPa pressure to obtain the all-solid-state battery of Example 1. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0115] Example 2: Positive electrode slurry preparation: The positive electrode active material is NCM811 ternary material, the binder is vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer (55:25:20), the sulfide electrolyte is LPSC, and the conductive agent is vapor-grown carbon fiber (VGCF). The content of each component in the positive electrode slurry is: positive electrode active material: sulfide electrolyte: binder: conductive agent = 57:37:2:4, and the solid content of the slurry is 40wt%.

[0116] Positive electrode preparation: The prepared slurry is coated onto aluminum foil and dried. The dried electrode is then cold-pressed using a roller press at a pressure of 250 MPa. The resulting positive electrode has an areal density of 15 mg / cm³. 2 .

[0117] Positive electrode surface coating with succinic acid: A toluene solution containing succinic acid and dodecyl mercaptan (succinic acid content 20wt%, dodecyl mercaptan content 2wt%, binder 1wt% (hydrogenated nitrile rubber, ZN35156), toluene 77wt%) is coated on the surface of the positive electrode. After drying, an electrode with succinic acid coated on the surface is obtained. The increase in areal density is controlled to be 0.5 mg / cm³ by adjusting the doctor blade thickness and coating speed. 2 .

[0118] Electrolyte membrane preparation: Under an inert gas atmosphere, 100 parts by weight of LPSC solid electrolyte material were mixed with 1 part by weight of SEBS binder, and then heptane was added to adjust the solid content to 40 wt%. A slurry for forming a solid electrolyte layer was coated onto an aluminum foil, dried, and then peeled off to obtain a solid electrolyte layer with a thickness of 50 micrometers.

[0119] Electrolyte membrane surface coating: Prepare a 20wt% LiTFSI DME solution, dissolve it evenly, then add 1wt% binder (hydrogenated nitrile rubber, Zetpol® 2010H), dissolve it evenly, and then coat it onto the surface of the prepared solid electrolyte membrane. After the solvent evaporates and dries, an electrolyte membrane with lithium salt coated on one side is obtained. The increase in areal density is controlled to be 0.25 mg / cm² by adjusting the doctor blade thickness and coating speed. 2 .

[0120] The molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is 7:1.

[0121] The negative electrode uses Li from Example 1. In alloy.

[0122] Positive electrode, solid electrolyte membrane, Li In alloy sheets are stamped into 10mm diameter discs. The surface of the resulting positive electrode is then bonded to the LiTFSI-coated surface of a solid electrolyte membrane. The uncoated surface of the solid electrolyte membrane and the Li... In alloy sheets were contacted and assembled into a molded battery. The battery was pressed under 300 MPa pressure, then heated to 70°C and held at that temperature for 3 hours. After cooling to room temperature, it was pressed again under 300 MPa pressure to obtain the all-solid-state battery of Example 2. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0123] Example 3: Positive electrode slurry preparation: The positive electrode active material is NCM811 ternary material, the binder is vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer (55:25:20), the sulfide electrolyte is LPSC, and the conductive agent is vapor-grown carbon fiber (VGCF). The content of each component in the positive electrode slurry is: positive electrode active material: sulfide electrolyte: binder: conductive agent = 57:37:2:4, and the solid content of the slurry is 40wt%.

[0124] Positive electrode preparation: The prepared slurry is coated onto aluminum foil and dried. The dried electrode is then cold-pressed using a roller press at a pressure of 250 MPa. The resulting positive electrode has an areal density of 15 mg / cm³. 2 .

[0125] Positive electrode surface coating with succinic acid: A toluene solution containing succinic acid and dodecyl mercaptan (succinic acid content 20wt%, dodecyl mercaptan content 2wt%, binder (hydrogenated nitrile rubber, ZN35156), toluene 77wt%) is coated on the surface of the positive electrode. After drying, an electrode with succinic acid coated on the surface is obtained. The increase in areal density is controlled to be 1 mg / cm³ by adjusting the doctor blade thickness and coating speed. 2 .

[0126] Electrolyte membrane preparation: Under an inert gas atmosphere, 100 parts by weight of LPSC solid electrolyte material were mixed with 1 part by weight of SEBS binder, and then heptane was added to adjust the solid content to 40 wt%. A slurry for forming a solid electrolyte layer was coated onto an aluminum foil, dried, and then peeled off to obtain a solid electrolyte layer with a thickness of 50 micrometers.

[0127] Electrolyte membrane surface coating: Prepare a 20wt% LiTFSI DME solution, dissolve it evenly, then add 1wt% binder (hydrogenated nitrile rubber, Zetpol® 2010H), dissolve it evenly, and then coat it onto the surface of the prepared solid electrolyte membrane. After the solvent evaporates and dries, an electrolyte membrane with lithium salt coated on one side is obtained. The increase in areal density is controlled to be 0.5 mg / cm² by adjusting the doctor blade thickness and coating speed. 2 .

[0128] The molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is 7:1.

[0129] The negative electrode uses Li In alloy.

[0130] Positive electrode, solid electrolyte membrane, Li In alloy sheets are stamped into 10mm diameter discs. The surface of the resulting positive electrode is then bonded to the LiTFSI-coated surface of a solid electrolyte membrane. The uncoated surface of the solid electrolyte membrane and the Li... In alloy sheets were contacted and assembled into a molded battery. The battery was pressed under 300 MPa pressure, then heated to 70°C and held at that temperature for 3 hours. After cooling to room temperature, it was pressed again under 300 MPa pressure to obtain the all-solid-state battery of Example 3. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0131] Example 4: Positive electrode slurry preparation: The positive electrode active material is NCM811 ternary material, the binder is vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer (55:25:20), the sulfide electrolyte is LPSC, and the conductive agent is vapor-grown carbon fiber (VGCF). The content of each component in the positive electrode slurry is: positive electrode active material: sulfide electrolyte: binder: conductive agent = 57:37:2:4, and the solid content of the slurry is 40wt%.

[0132] Positive electrode preparation: The prepared slurry is coated onto aluminum foil and dried. The dried electrode is then cold-pressed using a roller press at a pressure of 250 MPa. The resulting positive electrode has an areal density of 15 mg / cm³. 2 .

[0133] Positive electrode surface coating with succinic acid: A coating containing succinic acid and trithiocyanuric acid (succinic acid content 20wt%, trithiocyanuric acid content 2wt%, binder 1wt% (hydrogenated nitrile rubber, ZN35156), toluene 77wt%) is applied to the surface of the positive electrode. After drying, an electrode with a succinic acid coating is obtained. The increase in areal density is controlled to be 1 mg / cm³ by adjusting the doctor blade thickness and coating speed. 2 .

[0134] Electrolyte membrane preparation: Under an inert gas atmosphere, 100 parts by weight of LPSC solid electrolyte material were mixed with 1 part by weight of SEBS binder, and then heptane was added to adjust the solid content to 40 wt%. A slurry for forming a solid electrolyte layer was coated onto an aluminum foil, dried, and then peeled off to obtain a solid electrolyte layer with a thickness of 50 micrometers.

[0135] Electrolyte membrane surface coating: Prepare a 20wt% LiTFSI DME solution, dissolve it evenly, then add 1wt% binder (hydrogenated nitrile rubber, Zetpol® 2010H), dissolve it evenly, and then coat it onto the surface of the prepared solid electrolyte membrane. After the solvent evaporates and dries, an electrolyte membrane with lithium salt coated on one side is obtained. The increase in areal density is controlled to be 0.5 mg / cm² by adjusting the doctor blade thickness and coating speed. 2 .

[0136] The molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is 7:1.

[0137] The negative electrode uses Li In alloy.

[0138] Positive electrode, solid electrolyte membrane, Li In alloy sheets are stamped into 10mm diameter discs. The surface of the resulting positive electrode is then bonded to the LiTFSI-coated surface of a solid electrolyte membrane. The uncoated surface of the solid electrolyte membrane and the Li... In alloy sheets were contacted and assembled into a molded battery. The battery was pressed under 300 MPa pressure, then heated to 70°C and held at that temperature for 3 hours. After cooling to room temperature, it was pressed again under 300 MPa pressure to obtain the all-solid-state battery of Example 4. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0139] Example 5 The preparation method was the same as in Example 3, except that dodecyl mercaptan was not added. This yielded the all-solid-state battery of Example 5. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0140] Example 6 Positive electrode slurry preparation: The positive electrode active material is NCM811 ternary material, the binder is vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer (55:25:20), the sulfide electrolyte is LPSC, and the conductive agent is vapor-grown carbon fiber (VGCF). The content of each component in the positive electrode slurry is: positive electrode active material: sulfide electrolyte: binder: conductive agent = 57:37:2:4, and the solid content of the slurry is 40wt%.

[0141] Positive electrode preparation: The prepared slurry is coated onto aluminum foil and dried. The dried electrode is then cold-pressed using a roller press at a pressure of 250 MPa. The resulting positive electrode has an areal density of 15 mg / cm³. 2 .

[0142] Positive electrode surface coating with dimethyl sulfone: A cyclohexane solution containing dimethyl sulfone and dodecyl mercaptan (20 wt% dimethyl sulfone, 2 wt% dodecyl mercaptan, 1 wt% binder (hydrogenated nitrile rubber, ZN35156), 77 wt% cyclohexane) is coated onto the surface of the positive electrode. After drying, an electrode with a dimethyl sulfone coating is obtained. The increase in areal density is controlled to be 1 mg / cm³ by adjusting the doctor blade thickness and coating speed. 2 .

[0143] Electrolyte membrane preparation: Under an inert gas atmosphere, 100 parts by weight of LPSC solid electrolyte material were mixed with 1 part by weight of SEBS binder, and then heptane was added to adjust the solid content to 40 wt%. A slurry for forming a solid electrolyte layer was coated onto an aluminum foil, dried, and then peeled off to obtain a solid electrolyte layer with a thickness of 50 micrometers.

[0144] Electrolyte membrane surface coating: A 20wt% tetrahydrofuran solution of LiFSI was prepared and dissolved evenly. 1wt% binder (hydrogenated nitrile rubber, Zetpol® 2010H) was added and dissolved evenly. This binder was then coated onto the surface of the prepared solid electrolyte membrane. After solvent evaporation and drying, an electrolyte membrane with lithium salt coated on one side was obtained. The increase in areal density was controlled to be 0.5 mg / cm² by adjusting the doctor blade thickness and coating speed. 2 .

[0145] The molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is 4:1.

[0146] The negative electrode uses Li In alloy.

[0147] Positive electrode, solid electrolyte membrane, Li In alloy sheets are stamped into 10mm diameter discs. The surface of the resulting positive electrode is then bonded to the LiTFSI-coated surface of a solid electrolyte membrane. The uncoated surface of the solid electrolyte membrane and the Li... In alloy sheets were contacted and assembled into a molded battery. The battery was pressed under 300 MPa pressure, then heated to 70°C and held at that temperature for 3 hours. After cooling to room temperature, it was pressed again under 300 MPa pressure to obtain the all-solid-state battery of Example 6. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0148] Example 7 The preparation of the positive electrode and electrolyte membrane is the same as in Example 6; The coating of the positive electrode sheet is the same as in Example 6; The surface coating process and areal density control of the electrolyte membrane are the same as in Example 6. The difference is that in this example, both the upper and lower surfaces of the electrolyte membrane are coated, and after coating, the increase in the areal density of the electrolyte membrane is controlled to be 1 mg / cm³. 2 .

[0149] The negative electrode active material is graphite, the binder is styrene-butadiene rubber (SBR), the sulfide electrolyte is LPS, the binder is SEBS, and the conductive agent is vapor-grown carbon fiber (VGCF). The content of each component in the slurry is as follows: positive electrode active material: sulfide electrolyte: binder: conductive agent = 60:33:3:4, and the solid content of the slurry is 40wt%.

[0150] Negative electrode preparation: The prepared slurry is coated onto copper foil and dried. The dried electrode is then cold-pressed using a roller press at a pressure controlled at 150 MPa to obtain the negative electrode with an areal density of 10 mg / cm³. 2 .

[0151] Anode surface coating with dimethyl sulfone: A cyclohexane solution containing dimethyl sulfone and dodecyl mercaptan (20 wt% dimethyl sulfone, 2 wt% dodecyl mercaptan, 1 wt% binder (hydrogenated nitrile rubber, ZN35156), 77 wt% cyclohexane) is coated onto the surface of the anode. After drying, the electrode is obtained with a surface coated with dimethyl sulfone. The increase in areal density is controlled to be 0.5 mg / cm³ by adjusting the doctor blade thickness and coating speed. 2 .

[0152] The battery assembly is the same as in Example 6.

[0153] Comparative Example 1 The preparation method is the same as in Example 1, except that the coating on the positive electrode surface was adjusted compared to Example 1: a DME solution containing succinic anionylene and LiTFSI (12wt% succinic anionylene, 8% LiTFSI, 1wt% binder, and 79wt% DME) was coated on the positive electrode surface; no coating was applied to the electrolyte membrane surface; and lithium metal was used as the negative electrode. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0154] Comparative Example 2 The uncoated positive electrode, electrolyte membrane, and Li from Example 1 were used. All-solid-state batteries were assembled from In alloy sheets, and the electrochemical performance test results of the all-solid-state batteries are shown in Table 1.

[0155] Comparative Example 3 An all-solid-state battery was assembled from the uncoated positive electrode, electrolyte membrane, and negative electrode of Example 7. The electrochemical performance test results of the all-solid-state battery are shown in Table 1.

[0156] Table 1

[0157] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An all-solid-state battery, characterized in that, The all-solid-state battery includes a positive electrode, a solid electrolyte layer, and a negative electrode. A first eutectic electrolyte layer is disposed between the positive electrode and the solid electrolyte layer, and the first eutectic electrolyte layer includes a first eutectic electrolyte.

2. The all-solid-state battery according to claim 1, wherein, A second eutectic electrolyte layer is further disposed between the negative electrode sheet and the solid electrolyte layer, the second eutectic electrolyte layer including a second eutectic electrolyte; And / or, the first eutectic electrolyte may be the same as or different from the second eutectic electrolyte.

3. The all-solid-state battery according to claim 1 or 2, wherein, The first eutectic electrolyte and / or the second eutectic electrolyte are in a liquid and / or glassy state at 25±5℃; The first co-crystal electrolyte is the product obtained by co-crystallization reaction of the first hydrogen bond donor and the first hydrogen bond acceptor; The second eutectic electrolyte is the product obtained by co-crystallization reaction of the second hydrogen bond donor and the second hydrogen bond acceptor.

4. The all-solid-state battery according to claim 3, wherein, The first hydrogen bond donor and the second hydrogen bond donor may be the same or different; Preferably, the first hydrogen bond donor and the second hydrogen bond donor are each selected from at least one of methylacetamide, dimethylacetamide, 1,1,3,3-tetramethylurea, acetamide, benzamide, trifluoroacetamide, urea, acrylamide, butyrolactam, valproic acid lactone, caprolactam, heptanolactam, adiponitrile, ethylene carbonate, propanesulfonate lactone, sulfolane, methyl sulfolane, dimethyl sulfate, diethyl sulfate, formamide, dimethyl sulfone, dimethylmalononitrile, tetramethylsuccinate, cyclobutene sulfone, dithiopyridine, ethylene carbonate, trifluoroacetamide, methyl carbamate, dimethylimidazole, methylurea, dimethylurea, succinate, and thiourea. Preferably, the first hydrogen bond acceptor and the second hydrogen bond acceptor are the same or different; Preferably, the first hydrogen bond acceptor and the second hydrogen bond acceptor are each selected from soluble lithium salts; Preferably, the first hydrogen bond acceptor and the second hydrogen bond acceptor are each selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(perfluoroethylsulfonyl)imide, lithium (trifluoromethanesulfonyl)(perfluorobutylsulfonyl)imide, lithium (fluorosulfonyl)(perfluorobutylsulfonyl)imide, lithium bis(oxalatoborate)borate, and lithium nitrate. Preferably, in the first eutectic electrolyte layer, the molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is (2-30):1; Preferably, in the second eutectic electrolyte layer, the molar ratio of the second hydrogen bond donor to the second hydrogen bond acceptor is (2-30):

1.

5. The all-solid-state battery according to any one of claims 1-4, wherein, The first eutectic electrolyte layer and the second eutectic electrolyte layer each contain a binder. Preferably, based on the total amount of the first eutectic electrolyte layer and / or the second eutectic electrolyte layer, the content of the first eutectic electrolyte and / or the second eutectic electrolyte is 70-99 wt%, and the content of the binder is 1-30 wt%. Preferably, the content of the first eutectic electrolyte and / or the second eutectic electrolyte is 85-98 wt%, and the content of the binder is 2%-15 wt%. Preferably, the adhesive is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polymethyl methacrylate, polymethyl methacrylate copolymer, polymethyl acrylate, polymethyl acrylate copolymer, polyacrylonitrile, polyurethane, polyvinyl alcohol, polyacrylic acid, polyacrylic acid copolymer, and lithium polyacrylate. Preferably, the first eutectic electrolyte and / or the second eutectic electrolyte further contain a stabilizer; Preferably, the stabilizer is selected from one or more of dodecyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, trimethylsilane compounds, trithiocyanuric acid, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and bis(1,5-pentylene)thiuram tetrasulfide, more preferably dodecyl mercaptan and / or trithiocyanuric acid; Preferably, the stabilizer content is 0.1-10 wt%, preferably 1-5 wt%, based on the total amount of the first eutectic electrolyte layer and / or the second eutectic electrolyte layer.

6. The all-solid-state battery according to any one of claims 1-5, wherein, The positive electrode sheet includes a positive current collector and a positive active layer composited on the surface of the positive current collector; Preferably, the positive electrode active layer includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a sulfide electrolyte; Preferably, in the positive electrode active layer, the mass ratio of positive electrode active material, sulfide electrolyte, positive electrode binder, and positive electrode conductive agent is 100:(20-70):(0.1-5):(1-10). Preferably, the areal density of the positive electrode sheet is 5-30 mg / cm³. 2 ; Preferably, the positive electrode active material is selected from at least one of lithium cobalt oxide materials, nickel-cobalt-manganese ternary materials, lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials; Preferably, the sulfide electrolyte is selected from Li 7-a (M b P 1-b )SX a Li 10+c M 1+c P 2-c S 12 Li 21-e Si3M d P 3-d S 23 X e At least one of the following, X is selected from at least one of Cl, F, Br, I, OH, O, O2, N, M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, 0<a≤2, 0≤b≤1, -1≤c≤2, 0≤d≤3, 0≤e≤3.

7. The all-solid-state battery according to any one of claims 1-6, wherein, The solid electrolyte layer includes a support layer and a solid electrolyte membrane composited on the support layer. The solid electrolyte membrane includes a solid electrolyte material and an electrolyte layer binder. Preferably, the content of the electrolyte layer binder is 1-30 parts by weight relative to 100 parts by weight of solid electrolyte material; Preferably, the thickness of the solid electrolyte layer is 5-80 μm.

8. The all-solid-state battery according to any one of claims 1-7, wherein, The negative electrode sheet includes a negative electrode active material; Preferably, the negative electrode active material is selected from at least one of Li-In alloy, metallic lithium, micron-sized silicon, nano-sized silicon-carbon, nano-sized silicon-oxygen, and graphite.

9. A method for preparing an all-solid-state battery, characterized in that, Includes the following steps: (1) One of slurry A and slurry B is coated on one side surface of the positive electrode sheet and dried to obtain the treated positive electrode sheet; the other slurry is coated on the side surface of the solid electrolyte layer opposite to the positive electrode sheet and dried to obtain the treated solid electrolyte layer. Slurry A contains a first hydrogen bond donor, and slurry B contains a first hydrogen bond acceptor; (2) The treated positive electrode, the treated solid electrolyte layer and the negative electrode are assembled and shaped, and then eutectic treatment is performed.

10. The preparation method according to claim 9, wherein, Before step (2), the process further includes: coating one of slurry C and slurry D onto one side surface of the negative electrode sheet and drying it to obtain the treated negative electrode sheet; coating the other slurry onto the side surface of the solid electrolyte layer opposite to the negative electrode sheet and drying it to obtain the treated solid electrolyte layer; wherein slurry C and slurry D contain a second hydrogen bond donor and a second hydrogen bond acceptor, respectively.

11. The preparation method according to claim 9 or 10, wherein, The first hydrogen bond donor and the second hydrogen bond donor may be the same or different; Preferably, the first hydrogen bond donor and the second hydrogen bond donor are each selected from at least one of methylacetamide, dimethylacetamide, 1,1,3,3-tetramethylurea, acetamide, benzamide, trifluoroacetamide, urea, acrylamide, butyrolactam, valproic acid lactone, caprolactam, heptanolactam, adiponitrile, ethylene carbonate, propanesulfonate lactone, sulfolane, methyl sulfolane, dimethyl sulfate, diethyl sulfate, formamide, dimethyl sulfone, dimethylmalononitrile, tetramethylsuccinate, cyclobutene sulfone, dithiopyridine, ethylene carbonate, trifluoroacetamide, methyl carbamate, dimethylimidazole, methylurea, dimethylurea, succinate, and thiourea. Preferably, the first hydrogen bond acceptor and the second hydrogen bond acceptor are the same or different; Preferably, the first hydrogen bond acceptor or the second hydrogen bond acceptor is selected from soluble lithium salts; Preferably, the first hydrogen bond acceptor or the second hydrogen bond acceptor is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(perfluoroethylsulfonyl)imide, lithium (trifluoromethanesulfonyl)(perfluorobutylsulfonyl)imide, lithium (fluorosulfonyl)(perfluorobutylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalatoborate)borate, and lithium nitrate. Preferably, the molar ratio of the first hydrogen bond donor to the first hydrogen bond acceptor is (2-30):1; Preferably, the molar ratio of the second hydrogen bond donor to the second hydrogen bond acceptor is (2-30):1; Preferably, the coating amount of slurry A or slurry B increases the areal density of the positive electrode by 0.1-100 mg / cm³. 2 More preferably, 0.25-5 mg / cm³ 2 ; Preferably, the coating amount of slurry A or slurry B increases the density of the solid electrolyte layer by 0.1-100 mg / cm³. 2 More preferably, 0.25-5 mg / cm³ 2 ; Preferably, the coating amount of slurry C or slurry D increases the areal density of the negative electrode by 0.1-100 mg / cm³. 2 ; Preferably, the coating amount of slurry C or slurry D results in an increase in the density of the solid electrolyte layer of 0.1-100 mg / cm³. 2 ; Preferably, slurry A contains a stabilizer; Preferably, the stabilizer is selected from one or more of dodecyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, trimethylsilane compounds, trithiocyanuric acid, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and bis(1,5-pentylene)thiuram tetrasulfide, more preferably dodecyl mercaptan and / or trithiocyanuric acid; Preferably, based on the total amount of slurry A, the content of stabilizer is 0.1-10 wt%, more preferably 1-5 wt%; Preferably, slurry B contains a stabilizer; Preferably, the stabilizer is selected from one or more of dodecyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, trimethylsilane compounds, trithiocyanuric acid, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and bis(1,5-pentylene)thiuram tetrasulfide, more preferably dodecyl mercaptan and / or trithiocyanuric acid; Preferably, based on the total amount of slurry B, the stabilizer content is 0.1-10 wt%, more preferably 1-5 wt%; Preferably, slurry C contains a stabilizer; Preferably, the stabilizer is selected from one or more of dodecyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, trimethylsilane compounds, trithiocyanuric acid, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and bis(1,5-pentylene)thiuram tetrasulfide, more preferably dodecyl mercaptan and / or trithiocyanuric acid; Preferably, based on the total amount of slurry C, the stabilizer content is 0.1-10 wt%, more preferably 1-5 wt%; Preferably, slurry D contains a stabilizer; Preferably, the stabilizer is selected from one or more of dodecyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, trimethylsilane trithiocyanuric acid, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and bis(1,5-pentylene)thiuram tetrasulfide, more preferably dodecyl mercaptan and / or trithiocyanuric acid; Preferably, based on the total amount of slurry D, the content of stabilizer is 0.1-10 wt%, preferably 1-5 wt%.

12. The preparation method according to any one of claims 9-11, wherein, The slurry A, slurry B, slurry C, and slurry D also contain binders, with the binder content ranging from 0.1% to 10% based on the total amount of slurry. Preferably, the adhesive is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride copolymer, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polymethyl methacrylate, polymethyl methacrylate copolymer, polymethyl acrylate, polymethyl acrylate copolymer, polyacrylonitrile, polyurethane, polyvinyl alcohol, polyacrylic acid, polyacrylic acid copolymer, and lithium polyacrylate. Preferably, slurry A and slurry C further contain a first solvent, the content of which is 20-80 wt% based on the total amount of slurry. Preferably, the first solvent is selected from at least one of toluene, xylene, DME, and tetrahydrofuran; Preferably, slurry B and slurry D further contain a second solvent, with the content of the second solvent being 20-80 wt% based on the total amount of slurry. Preferably, the second solvent is selected from at least one of toluene, xylene, DME, and tetrahydrofuran.

13. The preparation method according to any one of claims 9-12, wherein, The method for preparing the positive electrode sheet includes: coating a positive electrode active slurry onto the surface of a positive electrode current collector, and then drying it; the positive electrode active slurry includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, and a sulfide electrolyte; Preferably, the mass ratio of the positive electrode active material, the sulfide electrolyte, the positive electrode binder, and the positive electrode conductive agent is 100:(20-70):(0.1-5):(1-10). Preferably, the positive electrode active slurry further contains a solvent; preferably, the solid content of the positive electrode active slurry is 40-80 wt%. Preferably, the areal density of the positive electrode sheet is 5-30 mg / cm³. 2 ; Preferably, the positive electrode active material is selected from at least one of lithium cobalt oxide materials, nickel-cobalt-manganese ternary materials, lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials; Preferably, the sulfide electrolyte is selected from Li 7-a (M b P 1-b )SX a Li 10+c M 1+c P 2-c S 12 Li 21-e Si3M d P 3-d S 23 X e At least one of the following, X is selected from at least one of Cl, F, Br, I, OH, O, O2, N, M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, 0<a≤2, 0≤b≤1, -1≤c≤2, 0≤d≤3, 0≤e≤3.

14. The preparation method according to any one of claims 9-13, wherein, The method for preparing the solid electrolyte layer includes: coating a solid electrolyte slurry onto the surface of a support layer, and then drying and peeling it off; the solid electrolyte slurry includes a solid electrolyte material and an electrolyte layer binder; Preferably, the content of the electrolyte layer binder is 1-30 parts by weight relative to 100 parts by weight of solid electrolyte material; Preferably, the solid electrolyte slurry further contains a solvent; preferably, the solid content of the solid electrolyte slurry is 30-80 wt%. Preferably, the thickness of the solid electrolyte layer is 5-80 μm; Preferably, the solid electrolyte material is selected from lithium thiophosphate, Li... 7-a (M b P 1-b )SX a Li 10+c M 1+c P 2-c S 12 Li 21- e Si3M d P 3-d S 23 X e At least one of the following, X is selected from at least one of Cl, F, Br, I, OH, O, O2, N, M is selected from at least one of Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, 0<a≤2, 0≤b≤1, -1≤c≤2, 0≤d≤3, 0≤e≤3; Preferably, the negative electrode sheet includes a negative electrode active material; Preferably, the negative electrode active material is selected from at least one of Li-In alloy, metallic lithium, micron-sized silicon, nano-sized silicon-carbon, nano-sized silicon-oxygen, and graphite.

15. The preparation method according to any one of claims 9-14, wherein, In step (2), the molding pressure is 10-500 MPa; Preferably, the conditions for the eutectic treatment include: a temperature of 35-100℃ and a time of 0.5-5h; Preferably, the preparation method further includes: performing secondary molding on the eutectic battery, wherein the pressure of the secondary molding is 10-400 MPa; preferably 300-400 MPa.

16. An all-solid-state battery prepared by the preparation method according to any one of claims 9-15.

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