Composite solid electrolyte, all-solid-state positive pole piece and preparation method and application of all-solid-state positive pole piece

Abstract

The invention provides a composite solid electrolyte, an all-solid-state positive pole piece and a preparation method and application thereof, the composite solid electrolyte is characterized by comprising a plurality of composite solid electrolyte particles, and each composite solid electrolyte particle at least comprises a conductive agent, an all-solid-state positive pole piece and an all-solid-state positive pole piece, and the solid electrolyte partially or completely wraps the conductive agent, and a network structure is formed between the conductive agent and the solid electrolyte. According to the composite solid electrolyte, the all-solid-state positive pole piece and the preparation method and application of the all-solid-state positive pole piece, a three-dimensional continuous conductive network can be constructed, and the electron and ion conduction efficiency can be improved, so that the rate capability and the cycle performance of an all-solid-state battery can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a composite solid electrolyte, a full-solid positive electrode sheet and a preparation method and application thereof. BACKGROUND

[0002] The full-solid battery can provide a safer next-generation power battery for users by replacing the flammable liquid electrolyte with a solid-state electrolyte, has higher energy density and better long-term cycle performance, and is considered to be the final form of commercialized lithium-ion batteries. Compared with the positive electrode sheet prepared by the wet method, the dry method for preparing the full-solid positive electrode sheet does not require the use of a solvent, and can avoid the side reaction between the solvent and the solid-state electrolyte. However, the dry method full-solid positive electrode sheet still has technical defects: the aspect ratio of the fibrous conductive carbon material such as carbon nanotubes is extremely high, and it is easy to intertwine to form agglomerates, so that the conductive carbon can only form point contact between the solid-state electrolyte and the positive electrode active material particles, and cannot build a continuous conductive network, which seriously restricts the electronic conduction efficiency of the dry method full-solid positive electrode. SUMMARY

[0003] The present application provides a composite solid electrolyte, a full-solid positive electrode sheet and a preparation method and application thereof, which can build a three-dimensional continuous conductive network, improve the electronic and ionic conduction efficiency, and thus improve the rate performance and cycle performance of the full-solid battery.

[0004] To solve the above technical problems, the present application provides a composite solid electrolyte, comprising a plurality of composite solid electrolyte particles, each of which comprises at least:

[0005] a conductive agent; and

[0006] a solid-state electrolyte, which partially or completely wraps the conductive agent, and a network structure is formed between the conductive agent and the solid-state electrolyte.

[0007] In an embodiment of the present application, in each of the composite solid electrolyte particles, the spacing between the conductive agent and the solid-state electrolyte is ≤20nm.

[0008] In an embodiment of the present application, the conductive agent is a one-dimensional conductive agent, and the aspect ratio of the one-dimensional conductive agent is ≥100.

[0009] In an embodiment of the present application, in each of the composite solid electrolyte particles, the diameter of the conductive agent is ≤200nm; and / or, for the plurality of composite solid electrolyte particles, the diameter of the conductive agent satisfies D90 / D10≤3.

[0010] In an embodiment of the present application, the solid-state electrolyte is selected from at least one of an oxide solid-state electrolyte, a sulfide solid-state electrolyte, and a halide solid-state electrolyte;

[0011] And / or, the conductive agent is selected from at least one of graphite, graphene, carbon black, nano-carbon fiber, and carbon nanotube;

[0012] And / or, the mass ratio of the solid-state electrolyte and the conductive agent is 1:0.08 to 1:0.15.

[0013] The present application also provides a preparation method of a composite solid-state electrolyte, at least comprising the following steps:

[0014] ball-milling the solid-state electrolyte raw material and the conductive agent to obtain a mixture; and

[0015] granulating the mixture to obtain an intermediate product, and sintering the intermediate product to obtain the composite solid-state electrolyte.

[0016] In an embodiment of the present application, in the ball-milling process, the ratio between the mass of the grinding ball and the total mass of the solid-state electrolyte raw material and the conductive agent is 10:1 to 30:1.

[0017] And / or, the rotation speed of the ball-milling is 300 rpm to 600 rpm.

[0018] And / or, the grinding ball in the ball-milling process comprises at least one of a zirconia ball, an alumina ball, and an agate ball.

[0019] And / or, the diameter of the grinding ball in the ball-milling process is 1 mm to 5 mm.

[0020] And / or, the pressure of the granulation is 50 MPa to 200 MPa.

[0021] And / or, the sintering temperature is 400℃ to 700℃.

[0022] And / or, the sintering time is 3 h to 6 h.

[0023] The present application also provides an all-solid-state positive electrode sheet, at least comprising:

[0024] a current collector; and

[0025] an all-solid-state positive electrode disposed on at least one surface of the current collector, and the all-solid-state positive electrode at least comprises a positive electrode active material, an electrolyte, and a binder, the electrolyte is selected from the composite solid-state electrolyte described above, or obtained according to the preparation method described above.

[0026] The present application also provides a preparation method of an all-solid-state positive electrode sheet, at least comprising the following steps:

[0027] mixing the positive active material and the electrolyte uniformly to obtain a premix, and mixing the premix and the binder uniformly to obtain a mixture;

[0028] performing a fibrillation treatment on the mixture to obtain a fibrillated material, and performing granulation on the fibrillated material to obtain a full-solid-state positive electrode material;

[0029] performing rolling on the full-solid-state positive electrode material to obtain a film, and performing thinning on the film to obtain a full-solid-state positive electrode; and

[0030] performing compounding on the full-solid-state positive electrode and a current collector to obtain a full-solid-state positive electrode sheet;

[0031] wherein a linear speed for mixing the positive active material and the electrolyte is 20 m / s to 40 m / s;

[0032] and / or a time for mixing the positive active material and the electrolyte is 20 min to 60 min;

[0033] and / or a temperature for mixing the positive active material and the electrolyte is 20℃ to 30℃;

[0034] and / or a linear speed for mixing the premix and the binder is 5 m / s to 20 m / s;

[0035] and / or a time for mixing the premix and the binder is 20 min to 60 min;

[0036] and / or a temperature for mixing the premix and the binder is 5℃ to 20℃;

[0037] and / or a temperature for the fibrillation treatment is 60℃ to 80℃;

[0038] and / or a linear speed for the fibrillation treatment is 40 m / s to 60 m / s;

[0039] and / or a time for the fibrillation treatment is 10 min to 30 min;

[0040] and / or a temperature for the thinning is 80℃ to 120℃.

[0041] The application also provides a full-solid-state battery, comprising at least:

[0042] a positive electrode sheet selected from the full-solid-state positive electrode sheet described above, or obtained according to the preparation method described above;

[0043] a negative electrode sheet; and

[0044] a solid electrolyte layer arranged between the positive electrode sheet and the negative electrode sheet.

[0045] To sum up, the application provides a composite solid-state electrolyte, a full-solid-state positive electrode sheet, and a preparation method and application thereof. By adding a conductive agent in the preparation process of the solid-state electrolyte, agglomeration of the conductive agent is avoided, the solid-state electrolyte is continuously wrapped around the conductive agent to build a three-dimensional continuous conductive network, the electron and ion conduction efficiency is improved, and thus the rate performance and cycle performance of the full-solid-state battery are improved. Moreover, the porosity of the full-solid-state positive electrode sheet can be reduced, the continuity of the ion conduction path and the stability of the electrode sheet structure are improved, and thus the performance of the battery is further improved. DETAILED DESCRIPTION

[0046] Other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied in other different specific embodiments, and various modifications or changes can be made to the details in the specification without departing from the spirit of the present application.

[0047] It should be understood that the present application can be implemented in different forms, and should not be interpreted as being limited to the embodiments presented herein. On the contrary, these embodiments are presented to make the disclosure complete and complete, and to fully convey the scope of the present application to those skilled in the art.

[0048] The technical solutions of the present application will be further described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0049] In practical applications, the dry full-solid-state positive electrode sheet has many technical defects: first, the aspect ratio of fibrous conductive carbon materials such as carbon nanotubes is extremely high, which is easy to intertwine to form agglomerates, so that the conductive carbon can only form point contact between the solid-state electrolyte and the positive active material particles, and cannot build a continuous conductive network, which seriously restricts the electron conduction efficiency of the dry full-solid-state positive electrode; second, the conductive carbon material has small particle size, large specific surface area, and high surface atom ratio, which causes strong van der Waals force between particles. In the high-temperature environment during the fiberization of the dry electrode, the thermal motion of the particles is intensified, the van der Waals force is enhanced, and the agglomeration between the conductive materials is further promoted. Therefore, the present application provides a composite solid-state electrolyte, a full-solid-state positive electrode sheet, and a preparation method and application thereof, which can continuously wrap the conductive carbon material and the solid-state electrolyte particles, in-situ composite build a three-dimensional continuous conductive network, and avoid agglomeration of the conductive agent, so as to improve the electron conduction efficiency, and further improve the rate performance and cycle performance of the full-solid-state battery.

[0050] The present application provides a composite solid-state electrolyte, comprising a plurality of composite solid-state electrolyte particles, each of which comprises at least a conductive agent and a solid-state electrolyte, and the solid-state electrolyte partially or completely covers the conductive agent. In each solid-state electrolyte particle, a network structure is formed between the conductive agent and the solid-state electrolyte to construct a three-dimensional continuous conductive network, thereby improving the electron and ion conduction efficiency and further improving the rate performance and cycle performance of the all-solid-state battery.

[0051] In an embodiment of the present application, in each composite solid-state electrolyte particle, the spacing between the conductive agent and the solid-state electrolyte is, for example, ≤20nm, so that the contact between the solid-state electrolyte and the conductive agent is more closely, and the contact between them becomes atomic level, thereby greatly improving the electron and ion conduction efficiency and further improving the rate performance and cycle performance of the all-solid-state battery.

[0052] In an embodiment of the present application, in each composite solid-state electrolyte particle, the conductive agent is, for example, selected from one-dimensional conductive agents, and the one-dimensional conductive agent is, for example, at least one of vapor-grown carbon fiber (VGCF) and carbon nanotubes (CNT). Further, in each composite solid-state electrolyte particle, the diameter of the conductive agent is, for example, ≤200nm, to avoid the phenomenon of agglomeration between the conductive agent particles in the composite solid-state electrolyte particle.

[0053] In an embodiment of the present application, in the composite solid-state electrolyte, for the conductive agent in the plurality of composite solid-state electrolyte particles, the diameter satisfies D90 / D10≤3, D90 refers to the diameter corresponding to the cumulative diameter proportion of 90% of the conductive agent after all the conductive agents are sorted in descending order of diameter, and D10 refers to the diameter corresponding to the cumulative diameter proportion of 10% of the conductive agent after all the conductive agents are sorted in descending order of diameter. By limiting D90 / D10, the size of the conductive agent in each composite solid-state electrolyte particle can be further limited to prevent agglomeration of the conductive agent.

[0054] In an embodiment of the present application, the solid-state electrolyte is selected from at least one of oxide solid-state electrolytes, sulfide solid-state electrolytes, and halide solid-state electrolytes, and the oxide solid-state electrolyte is, for example, at least one of Li 0.5 La 0.5 TiO3 and Li7La3Zr2O 12 , the sulfide solid-state electrolyte is, for example, at least one of Li6PS5Cl, Li7P3S 11 , and Li 10 GeP2S 12The solid-state electrolyte includes at least one of Li2MnCl4, Li2ZnCl4, and the like, and the halide solid-state electrolyte includes at least one of Li2MnCl4, Li2ZnCl4, and the like. In addition, the mass ratio of the solid-state electrolyte and the conductive agent is, for example, 1:0.08 to 1:0.15, which can improve the rate performance and cycle performance of the all-solid-state battery.

[0055] The application further provides a preparation method of the composite solid-state electrolyte, including at least steps S11-S12.

[0056] In step S11, the solid-state electrolyte raw material and the conductive agent are ball milled to obtain a mixture.

[0057] In step S12, the mixture is granulated to obtain an intermediate product, and the intermediate product is sintered to obtain the composite solid-state electrolyte.

[0058] In an embodiment of the application, in step S11, the solid-state electrolyte raw material, the conductive agent, and the grinding balls are ball milled to obtain a mixture according to the chemical formula of the solid-state electrolyte and the mass ratio of the solid-state electrolyte and the conductive agent. The mass ratio of the grinding balls to the total mass of the solid-state electrolyte raw material and the conductive agent is, for example, 100:1 to 30:1, the rotation speed of the ball mill is, for example, 300 rpm to 600 rpm, the ball milling time is, for example, 1 h to 6 h, and the grinding balls include at least one of zirconia balls, alumina balls, agate balls, and the like, and the diameter of the grinding balls is, for example, 1 mm to 5 mm. In this embodiment, the solid-state electrolyte raw material is described by taking Li6PS5Cl sulfide solid-state electrolyte as an example. The solid-state electrolyte raw material includes, for example, a Li source, a P source, an S source, and a Cl source. The Li source includes, for example, Li2S and LiCl, the P source is, for example, P2S5, the S source is derived from the Li source and the P source, and the Cl source is derived from the Li source. The purity of the Li source, the P source, the S source, and the Cl source is, for example, greater than or equal to 99 wt%. By adding the conductive agent in the preparation process of the solid-state electrolyte, the conductive agent is continuously wrapped between the solid-state electrolyte particles, a three-dimensional continuous conductive network is constructed in situ, and the agglomeration of the conductive agent is avoided, thereby realizing efficient ion and electron transmission, improving the performance of the all-solid-state positive electrode sheet, and greatly improving the long cycle performance and rate performance of the all-solid-state lithium ion battery.

[0059] In an embodiment of the present application, after the mixture is obtained, the mixture is granulated in step S12 to obtain an intermediate product, and then the intermediate product is sintered to obtain a plurality of composite solid electrolyte particles, i.e., a composite solid electrolyte. The pressure of the granulation is, for example, 50 MPa to 200 MPa, the sintering temperature is, for example, 400 DEG C to 700 DEG C, and the sintering time is, for example, 3 h to 6 h. If the solid electrolyte and the conductive agent are directly mechanically mixed, the conductive agents will agglomerate, the contact between the agglomerated conductive agents and the solid electrolyte is point contact, the point contact will form more pores, which will deteriorate the ion and electron transmission, and at the same time, the agglomerated conductive agents cannot fully utilize their conductive properties, only the surface conductive agents can play a role in electron transmission, and the internal conductive agents cannot function. Therefore, in the present application, by a specific preparation method, the conductive agent which is easy to agglomerate and difficult to disperse is used as a carrier by the solid electrolyte particles, which can realize the uniform dispersion of the conductive agent and avoid the agglomeration of the conductive agent, so as to fully utilize the conductive properties of the conductive agent, improve the electron and ion transmission efficiency, and further improve the rate performance and cycle performance of the all-solid-state battery.

[0060] The present application also provides an all-solid-state positive electrode sheet, which comprises, for example, a current collector and an all-solid-state positive electrode, wherein the all-solid-state positive electrode is arranged on at least one surface of the current collector, and the all-solid-state positive electrode comprises at least a positive electrode active material, an electrolyte and a binder. The electrolyte is, for example, the composite solid electrolyte described above, or the composite solid electrolyte obtained according to the preparation method described above, and will not be described in detail herein.

[0061] In an embodiment of the present application, the current collector is, for example, a foil formed after surface treatment of nickel, titanium, aluminum, silver, stainless steel or carbon, and the current collector can also be in the form of a film, a net, a porous material, a foam or a non-woven fabric, or a combination of any one or more of the above forms, and the thickness of the current collector can be selected according to actual needs. Specifically, the thickness of the current collector is, for example, 6 μm to 20 μm. In this embodiment, the current collector is, for example, a carbon-coated aluminum foil, and the thickness of the carbon-coated layer in the carbon-coated aluminum foil is, for example, 0.5 μm to 3 μm, and the thickness of the aluminum foil is, for example, 5.5 μm to 17 μm.

[0062] In an embodiment of the present application, in the all-solid-state positive electrode, the mass ratio of the positive electrode active material, the electrolyte and the binder is, for example, (67-89):(10-30):(1-3). Specifically, the positive electrode active material comprises, for example, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and lithium-rich manganese-based oxide, and in this embodiment, the positive electrode active material is, for example, LiNi 0.8 Co 0.1 Mn 0.1O2, the binder for example includes at least one of polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer, ethylene-vinyl acetate copolymer, polypropylene, polyethylene, ethylene-octene copolymer, and polyimide, etc.

[0063] The application further provides a preparation method of the all-solid-state positive electrode sheet, including at least steps S21-S24.

[0064] In step S21, the positive active material and the electrolyte are mixed uniformly to obtain a premix, and then the premix is mixed with the binder uniformly to obtain a mixture.

[0065] In step S22, the mixture is subjected to fibrillation treatment to obtain a fibrillated material, and then the fibrillated material is granulated to obtain an all-solid-state positive electrode material.

[0066] In step S23, the all-solid-state positive electrode material is rolled into a film, and then the film is thinned to obtain an all-solid-state positive electrode.

[0067] In step S24, the all-solid-state positive electrode and the current collector are compounded to obtain an all-solid-state positive electrode sheet.

[0068] In an embodiment of the application, in step S21, the positive active material and the electrolyte are stirred and mixed uniformly to obtain a premix. In the process of mixing the positive active material and the electrolyte, the linear speed of the stirring paddle is for example 20 m / s to 40 m / s, the mixing time of the positive active material and the electrolyte is for example 20 min to 60 min, and the mixing temperature of the positive active material and the electrolyte is for example 20℃ to 30℃.

[0069] In an embodiment of the application, after the premix is obtained, in step S21, the premix and the binder are continuously mixed uniformly to obtain a mixture. In the process of mixing the premix and the binder, the linear speed of the stirring paddle is for example 5 m / s to 20 m / s, the mixing time of the premix and the binder is for example 20 min to 60 min, and the mixing temperature of the premix and the binder is for example 5℃ to 20℃.

[0070] In an embodiment of the application, after the mixture is obtained, in step S22, the mixture is put into a blender for fibrillation treatment to obtain a fibrillated material, and then the fibrillated material is crushed and granulated to obtain an all-solid-state positive electrode material. In the fibrillation treatment, the temperature is for example 60℃ to 80℃, the linear speed of the stirring paddle in the fibrillation treatment is for example 40 m / s to 60 m / s, and the fibrillation treatment time is for example 10 min to 30 min.

[0071] In an embodiment of the present application, after obtaining the all-solid-state positive electrode material, the all-solid-state positive electrode material is rolled into a film and then thinned to a target surface capacity in step S23 to obtain an all-solid-state positive electrode. In the thinning process, the temperature of the all-solid-state positive electrode material is, for example, 80-120°C, and the target surface capacity is, for example, 2-8 mAh / cm 2 2 .

[0072] In an embodiment of the present application, after obtaining the all-solid-state positive electrode, the all-solid-state positive electrode is compounded on at least one surface of the current collector in step S24 to obtain an all-solid-state positive electrode sheet. If the solid-state electrolyte and the conductive agent are simply mechanically mixed, agglomeration will occur between the conductive agents. After agglomeration, the contact between the conductive agent and the solid-state electrolyte is point contact, which will form more pores. Therefore, in the present application, the conductive agent which is prone to agglomeration and difficult to disperse is carried by the solid-state electrolyte particles, which can reduce the porosity of the all-solid-state positive electrode sheet, thereby improving the continuity of the ion conduction path and the stability of the sheet structure, and further improving the rate performance and cycle performance of the all-solid-state battery.

[0073] The present application also provides an all-solid-state battery, for example, a primary battery or a secondary battery, for example, a soft-pack battery, a hard-shell battery, or a cylindrical battery. The present application does not specifically limit the type and category of the all-solid-state battery. The all-solid-state battery, for example, includes a positive electrode sheet, a negative electrode sheet, and a solid-state electrolyte layer. The positive electrode sheet is, for example, the all-solid-state positive electrode sheet described above or the all-solid-state positive electrode sheet obtained by the preparation method described above, which will not be described in detail here.

[0074] ​In an embodiment of the present application, the negative electrode tab is, for example, an indium tab, a lithium tab, an aluminum tab, or an alloy tab composed of at least two of the above-mentioned metals. In other embodiments of the present application, the negative electrode tab further includes, for example, a negative electrode current collector and a negative electrode active layer coated on at least one side surface of the negative electrode current collector. The negative electrode current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foamed copper current collector, a stainless steel current collector, or the like. The negative electrode active layer includes, for example, a negative electrode active material, a negative electrode electrolyte, a negative electrode conductive agent, a negative electrode binder, or the like. The present application does not limit the mass ratio of the negative electrode active material, the negative electrode electrolyte, the negative electrode conductive agent, and the negative electrode binder, which can be selected according to actual needs. The negative electrode active material includes, for example, at least one of a graphite-based material or a silicon material. The graphite-based material includes, for example, at least one of natural graphite or artificial graphite. The natural graphite includes, for example, at least one of blocky graphite, flaky graphite, or earthy graphite. The artificial graphite includes, for example, at least one of single crystal graphite, polycrystal graphite, pyrolytic graphite, or graphite fiber. The silicon material includes, for example, at least one of crystalline silicon, amorphous silicon, and organic silicon. The negative electrode electrolyte is, for example, a sulfide solid-state electrolyte. The negative electrode conductive agent includes, for example, at least one of graphite, graphene, SuperP, VGCF, or a carbon nanotube. The negative electrode binder includes, for example, at least one of PVDF, ethylene-propylene-diene monomer, styrene-butadiene rubber, fluorine rubber, polyvinylidene fluoride-hexafluoropropylene copolymer, or polyvinylidene fluoride-trifluorochloroethylene copolymer.

[0075] In an embodiment of the present application, a solid-state electrolyte layer is arranged between the positive electrode tab and the negative electrode tab. The material of the solid-state electrolyte layer includes, for example, at least one of an oxide solid-state electrolyte, a sulfide solid-state electrolyte, or a halide solid-state electrolyte. The solid-state electrolyte layer can be obtained by a dry method or a wet method. The dry method includes, for example, a hot-pressing method, a cold-pressing method, or a mechanical ball-milling method. The wet method includes, for example, a casting method, a sol-gel method, or an electrochemical deposition method. In this embodiment, a Li6PS5Cl solid-state electrolyte layer with a preset diameter of 10 mm is prepared by a cold-pressing method. Specifically, a Li6PS5Cl powder with a preset mass is put into a mold with a diameter of 10 mm, and is pressed to a preset pressure to obtain the solid-state electrolyte layer. The preset mass is, for example, 1000 mg, and the preset pressure is, for example, 100 MPa.

[0076] In an embodiment of the present application, the above-mentioned positive electrode tab, solid-state electrolyte layer, and negative electrode tab are sequentially laminated, packaged, and pressed to make the full-solid-state positive electrode in the full-solid-state positive electrode tab face the solid-state electrolyte layer, thereby assembling a full-solid-state battery. The assembly process is completed in an argon atmosphere glove box. The pressure of the pressing is, for example, 80 MPa-150 MPa.

[0077] The present application will be explained more specifically by the following examples, which should not be construed as limiting. Proper modifications can be made within the scope of the gist of the present application, which all fall within the technical scope of the present application.

[0078] Example 1

[0079] Preparation of the composite solid-state electrolyte: according to the chemical formula of the Li6PS5Cl sulfide solid-state electrolyte, Li2S with a purity of 99wt%, LiCl with a purity of 99wt%, and P2S5 with a purity of 99wt% were loaded into a zirconia jar as three solid-state electrolyte raw materials, and VGCF and zirconia balls with a diameter of 3mm were added, and the mixture was ball-milled in a planetary ball mill at 450rpm for 2 hours. Among them, the mass of the VGCF was equivalent to 6% of the total mass of the three solid-state electrolyte raw materials, and the ratio between the mass of the zirconia balls and the sum of the masses of the three solid-state electrolyte raw materials and the VGCF was 30:1. Next, 10g of the mixture was granulated under 100MPa to obtain an intermediate product, and then the intermediate product was placed in a vacuum environment and sintered at 550℃ for 4h to obtain a plurality of composite solid-state electrolyte particles, i.e. the composite solid-state electrolyte.

[0080] Preparation of the all-solid-state positive electrode sheet: the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 and the composite solid-state electrolyte were stirred and mixed uniformly, the linear speed of the stirring paddle was 30m / s, the mixing time was 40min, and the mixing temperature was 25℃. A premix was obtained. Next, the premix and PTFE were further mixed uniformly, the linear speed of the stirring paddle was 15m / s, the mixing time was 30min, and the mixing temperature was 10℃, to obtain a mixture. Then, the mixture was placed in a blender for fibrillation treatment, the fibrillation treatment temperature was 80℃, the linear speed of the stirring paddle during the fibrillation treatment was 40m / s, and the fibrillation treatment time was 10min, to obtain a fibrillated material, and then the fibrillated material was broken and granulated to obtain an all-solid-state positive electrode material. Finally, the all-solid-state positive electrode material was rolled into a film and then thinned to a surface capacity of 4mAh / cm 2 , to obtain an all-solid-state positive electrode, and then the all-solid-state positive electrode was compounded on one surface of a carbon-coated aluminum foil to obtain an all-solid-state positive electrode sheet. Among them, the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 was sourced from Xiamen Tungsten Co., Ltd., and the model was M821A, and the PTFE was sourced from Daikin, and the model was Polyflon TM M-18, with a molecular weight of 6000kg / mol, and the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1The mass ratio of O2, composite solid-state electrolyte and PTFE is 80:19:1, the thickness of the carbon coating layer in the carbon-coated aluminum foil is 1 μm, the thickness of the aluminum foil is 4 μm, and the diameter of the all-solid-state positive electrode sheet is 10 mm.

[0081] Selection of negative electrode sheet: a lithium-indium alloy sheet with a diameter of 10 mm is selected as the negative electrode sheet.

[0082] Preparation of solid-state electrolyte layer: 1000 mg of Li6PS5Cl powder is placed in a mold with a diameter of 10 mm, and is pressed to 100 MPa to obtain a solid-state electrolyte layer.

[0083] Preparation of battery: In an argon atmosphere glove box, the all-solid-state positive electrode sheet and lithium-indium alloy sheet are placed on both sides of the solid-state electrolyte layer and assembled, with the all-solid-state positive electrode in the all-solid-state positive electrode sheet facing the solid-state electrolyte layer. After assembly, the pressure is increased to 100 MPa, and the nuts at the top of the stand are tightened to maintain the pressure, thereby obtaining an all-solid-state lithium ion battery.

[0084] Characterization of spacing between conductive agent and solid-state electrolyte in each composite solid-state electrolyte particle: The all-solid-state positive electrode sheet is cut using a focused ion beam, and at least 20 interfaces between the conductive agent and the solid-state electrolyte in the composite solid-state electrolyte particles are located in the atomic resolution mode of the 300 kV field emission transmission electron microscope. The spacing between the conductive agent and the solid-state electrolyte is calculated, and the average value is taken as the final spacing. In this embodiment, the spacing is 25 nm.

[0085] Characterization of conductive agent diameter in each composite solid-state electrolyte particle: The diameters of the conductive agent in at least 5 particles are measured by transmission electron microscopy, and the arithmetic mean of at least 5 diameters is finally taken. In this embodiment, the diameter is 250 nm.

[0086] Characterization of D90 / D10 in multiple composite solid-state electrolyte particles: 5 regions are randomly selected on each composite solid-state electrolyte particle (the spacing between adjacent two regions is ≥10 μm), 3 fields of view (magnification 50000X) are collected for each region by transmission electron microscopy, and the diameters of 4 conductive agents are randomly measured in each field of view (a total of 60 data points). The diameter distribution curve is fitted using ImageJ software, and the D10 and D90 values are calculated to obtain the D90 / D10 ratio. The above process is repeated for 3 independent sample preparation tests, and the arithmetic mean of the D90 / D10 ratio is finally taken. In this embodiment, D90 / D10 is 3.5.

[0087] Example 2

[0088] The sintering time is adjusted to 5 h, the spacing between the conductive agent and the solid-state electrolyte is 20 nm, and the other steps are the same as in Example 1.

[0089] Example 3

[0090] The sintering time was adjusted to 5 h, the granulation pressure was 120 MPa, the distance between the conductive agent and the solid electrolyte was 15 nm, and the other steps were the same as in Example 1.

[0091] Example 4

[0092] The ball milling rotation speed was adjusted to 550 rpm, the diameter of the conductive agent was 200 nm, and the other steps were the same as in Example 1.

[0093] Example 5

[0094] The ball milling rotation speed was adjusted to 600 rpm, the diameter of the conductive agent was 150 nm, and the other steps were the same as in Example 1.

[0095] Example 6

[0096] The ball milling rotation speed was adjusted to 550 rpm, the sintering time was adjusted to 5 h, the distance between the conductive agent and the solid electrolyte was 20 nm, the diameter of the conductive agent was 200 nm, and the other steps were the same as in Example 1.

[0097] Example 7

[0098] The ball milling time was adjusted to 3 h, D90 / D10 was 3, and the other steps were the same as in Example 1.

[0099] Example 8

[0100] The ball milling time was adjusted to 5 h, D90 / D10 was 2.5, and the other steps were the same as in Example 1.

[0101] Example 9

[0102] The ball milling rotation speed was adjusted to 550 rpm, the ball milling time was adjusted to 3 h, the sintering time was adjusted to 5 h, the distance between the conductive agent and the solid electrolyte was 20 nm, the diameter of the conductive agent was 200 nm, D90 / D10 was 3, and the other steps were the same as in Example 1.

[0103] Example 10

[0104] The mass of the VGCF was equivalent to 8% of the total mass of the three solid electrolyte raw materials, and the other steps were the same as in Example 1.

[0105] Example 11

[0106] The mass of the VGCF was equivalent to 10% of the total mass of the three solid electrolyte raw materials, and the other steps were the same as in Example 1.

[0107] Example 12

[0108] The mass of the VGCF is 15% of the total mass of the three solid electrolyte raw materials, and the other steps are the same as in Example 1.

[0109] Example 13

[0110] The mass of the VGCF is 20% of the total mass of the three solid electrolyte raw materials, and the other steps are the same as in Example 1.

[0111] Example 14

[0112] The mass of the VGCF is 10% of the total mass of the three solid electrolyte raw materials, and the other steps are the same as in Example 9.

[0113] Comparative Example 1

[0114] No VGCF is added in the preparation process of the composite solid electrolyte, and the VGCF, the positive active material LiNi 0.8 Co 0.1 Mn 0.1 O2 and the composite solid electrolyte are added together in the preparation process of the all-solid-state positive electrode sheet, and the other steps are the same as in Example 1.

[0115] In the present application, the performance of the all-solid-state batteries in Examples 1-14 and Comparative Example 1 is tested.

[0116] In an embodiment of the present application, for example, the all-solid-state battery is subjected to a normal temperature cycle test. Specifically, the all-solid-state battery is subjected to a long cycle charge and discharge at a constant capacity of 0.6 mA at 25°C, and the first cycle constant capacity discharge specific capacity and the normal temperature cycle number when the battery state of health (SOH) is 80% are recorded. The normal temperature cycle test rate is 0.3C, the working voltage range of the battery is 1.9V-3.7V, and the recorded results are shown in Table 1.

[0117] In an embodiment of the present application, for example, the all-solid-state battery is subjected to a rate performance test. Specifically, the all-solid-state battery is subjected to a constant current discharge at a rate of 2C to a discharge cut-off voltage of 1.9V after being charged to a cut-off voltage of 3.7V and standing at 25°C, and the discharge capacity is recorded. Then, the ratio between the discharge capacity and the mass of the positive active material is calculated as the 2C discharge specific capacity, and the recorded results are shown in Table 1.

[0118] Table 1, characterization data of the composite solid electrolyte and the all-solid-state battery in Examples 1-14 and Comparative Example 1

[0119]

[0120]

[0121] As shown in Table 1, comparative example 1 and comparative example 1 can be known, relative to the mixing of solid electrolyte and conductive agent, the battery prepared by adding conductive agent in the preparation process of solid electrolyte has higher first circle discharge specific capacity, normal temperature cycle number and 2C discharge specific capacity, thereby indicating that: if the solid electrolyte and the conductive agent are directly mechanically mixed, the conductive agent will be agglomerated, the contact between the agglomerated conductive agent and the solid electrolyte is point contact, the point contact will form more pores, which will deteriorate the ion and electron transmission, and the agglomerated conductive agent cannot fully utilize its conductivity, only the surface conductive agent can play the role of electron transmission, and the internal conductive agent cannot function. Therefore, in the present application, the conductive agent is added in the preparation process of the solid electrolyte, which can realize the uniform dispersion of the conductive agent which is easy to agglomerate and difficult to disperse by using the solid electrolyte particles as carriers, thereby avoiding the agglomeration of the conductive agent, fully utilizing the conductivity of the conductive agent, improving the electron and ion conduction efficiency, and further improving the rate performance and cycle performance of the all-solid-state battery.

[0122] As shown in Table 1, comparative examples 1-3 can be known that when the spacing between the conductive agent and the solid electrolyte is more than 20 nm, i.e. reaches 25 nm, the first circle discharge specific capacity, normal temperature cycle number and 2C discharge specific capacity of the battery are reduced, thereby indicating that: by the spacing between the conductive agent and the solid electrolyte ≤20 nm, the contact between the solid electrolyte and the conductive agent can be closer, the contact between them becomes atomic level, thereby greatly improving the electron and ion conduction efficiency, and further improving the rate performance and cycle performance of the all-solid-state battery.

[0123] As shown in Table 1, comparative example 1 and examples 4-5 can be known that when the diameter of the conductive agent is greater than 200 nm, i.e. reaches 250 nm, the first circle discharge specific capacity, normal temperature cycle number and 2C discharge specific capacity of the battery are reduced, thereby indicating that: by limiting the diameter of the conductive agent ≤200 nm, the size of the conductive agent is limited, the agglomeration phenomenon between the conductive agent particles in the composite solid electrolyte particles is alleviated, and the rate performance and cycle performance of the all-solid-state battery are further improved.

[0124] As shown in Table 1, comparative example 1 and examples 7-8 can be known that when the diameter of the conductive agent in the plurality of composite solid electrolyte particles satisfies D90 / D10 greater than 3, i.e. reaches 3.5, the first circle discharge specific capacity, normal temperature cycle number and 2C discharge specific capacity of the battery are reduced, thereby indicating that: by limiting D90 / D10 ≤3, the size of the conductive agent in each composite solid electrolyte particle can be limited, the agglomeration of the conductive agent is prevented, and the rate performance and cycle performance of the all-solid-state battery are further improved.

[0125] Please refer to Table 1. Comparing Examples 1 and 10-13, it can be seen that when the mass ratio of conductive agent to solid electrolyte is lower than 0.08:1, i.e., reaches 0.06:1, the battery's first-cycle discharge specific capacity, room temperature cycle count, and 2C discharge specific capacity are relatively low. When the mass ratio of conductive agent to solid electrolyte is greater than 0.15:1, i.e., reaches 0.2:1, the battery's first-cycle discharge specific capacity, room temperature cycle count, and 2C discharge specific capacity are also relatively low. This indicates that by controlling the mass ratio of solid electrolyte to conductive agent to be between 1:0.08 and 1:0.15, the rate performance and cycle performance of all-solid-state batteries can be improved.

[0126] Please refer to Table 1. Comparing Examples 2, 6, 9, and 14, it can be seen that when the four parameters are met—the spacing between the conductive agent and the solid electrolyte ≤ 20 nm, the diameter of the conductive agent ≤ 200 nm, D90 / D10 ≤ 3, and the mass ratio of the solid electrolyte to the conductive agent being 1:0.08 to 1:0.15—the battery's first-cycle discharge specific capacity, room-temperature cycle count, and 2C discharge specific capacity can all maintain high values. This indicates that by simultaneously controlling the spacing between the conductive agent and the solid electrolyte, the diameter of the conductive agent, D90 / D10, and the mass ratio of the solid electrolyte to the conductive agent, the rate performance and cycle performance of the all-solid-state battery can be further improved.

[0127] This invention also provides an electronic device comprising at least one of the aforementioned all-solid-state batteries, which provides electrical energy. The electronic device can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, or power tool, etc. In one embodiment of this invention, the vehicle is, for example, a new energy vehicle, which can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The electronic device includes the aforementioned all-solid-state battery, and therefore the advantages of including the aforementioned all-solid-state battery are not elaborated here.

[0128] In summary, the application provides a composite solid-state electrolyte, a full-solid-state positive electrode sheet and a preparation method and application thereof. By adding a conductive agent in the preparation process of the solid-state electrolyte, the conductive agent is avoided to be aggregated, the solid-state electrolyte is continuously netted to wrap the conductive agent, a three-dimensional continuous conductive network is constructed, the electronic and ionic conduction efficiency is improved, and the rate performance and cycle performance of the full-solid-state battery are improved. Moreover, the porosity of the full-solid-state positive electrode sheet can be reduced, the continuity of the ionic conduction path and the stability of the electrode sheet structure are improved, and the performance of the battery is further improved.

[0129] The above description is only the preferred embodiment of the application and the explanation of the applied technical principles, and those skilled in the art should understand that the application range involved in the application is not limited to the technical solutions formed by the specific combination of the above technical features, and also covers other technical solutions formed by any combination of the above technical features or equivalent features without departing from the inventive concept, for example, the technical solutions formed by replacing the above features with the technical features disclosed in the application (but not limited to) having similar functions.

[0130] In addition to the technical features described in the specification, the remaining technical features are known to those skilled in the art, and in order to highlight the innovative features of the application, the remaining technical features will not be described here.

Claims

1. A composite solid electrolyte, characterized in that, It includes multiple composite solid electrolyte particles, each of which includes at least: Conductive agents; and A solid electrolyte partially or completely encapsulates the conductive agent, and a network structure is formed between the conductive agent and the solid electrolyte.

2. The composite solid electrolyte according to claim 1, characterized in that, In each of the composite solid electrolyte particles, the spacing between the conductive agent and the solid electrolyte is ≤20nm.

3. The composite solid electrolyte according to claim 1, characterized in that, The conductive agent is a one-dimensional conductive agent, and the aspect ratio of the one-dimensional conductive agent is ≥100.

4. The composite solid electrolyte according to claim 3, characterized in that, In each of the composite solid electrolyte particles, the diameter of the conductive agent is ≤200 nm; and / or, for the plurality of composite solid electrolyte particles, the diameter of the conductive agent satisfies D90 / D10≤3.

5. The composite solid electrolyte according to claim 1, characterized in that, The solid electrolyte is selected from at least one of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes; And / or, the conductive agent is selected from at least one of graphite, graphene, carbon black, carbon nanofibers and carbon nanotubes; And / or, the mass ratio of the solid electrolyte to the conductive agent is 1:0.08 to 1:0.

15.

6. A method for preparing a composite solid electrolyte as described in any one of claims 1 to 5, characterized in that, At least the following steps are included: Solid electrolyte raw materials and conductive agents are ball-milled to obtain a mixture; and The mixture is granulated to obtain an intermediate product, and the intermediate product is sintered to obtain a composite solid electrolyte.

7. The method for preparing the composite solid electrolyte according to claim 6, characterized in that, During the ball milling process, the ratio between the mass of the grinding balls and the total mass of the solid electrolyte raw material and the conductive agent is 10:1 to 30:

1. And / or, the ball mill rotates at a speed of 300 rpm to 600 rpm; And / or, the grinding balls used in the ball milling process include at least one of zirconia balls, alumina balls, and agate balls; And / or, the diameter of the grinding balls during the ball milling process is 1 mm to 5 mm; And / or, the granulation pressure is from 50 MPa to 200 MPa; And / or, the sintering temperature is 400°C to 700°C; And / or, the sintering time is 3 to 6 hours.

8. A fully solid-state positive electrode, characterized in that, At least including: current collector; as well as An all-solid-state positive electrode is disposed on at least one surface of the current collector, and the all-solid-state positive electrode comprises at least a positive electrode active material, an electrolyte, and a binder, wherein the electrolyte is selected from the composite solid electrolyte according to any one of claims 1 to 5, or the composite solid electrolyte obtained by the preparation method according to any one of claims 6 to 7.

9. A method for preparing an all-solid-state positive electrode sheet as described in claim 8, characterized in that, At least the following steps are included: The positive electrode active material and electrolyte are mixed evenly to obtain a premix, which is then mixed evenly with a binder to obtain a mixture. The mixture is subjected to fiberization treatment to obtain fibrillated material, which is then granulated to obtain all-solid cathode material; The all-solid cathode material is rolled into a film and then thinned to obtain an all-solid cathode. as well as The all-solid-state positive electrode and the current collector are combined to obtain an all-solid-state positive electrode sheet; The linear velocity for mixing the positive electrode active material and the electrolyte is 20 m / s to 40 m / s. And / or, the mixing time of the positive electrode active material and the electrolyte is 20 min to 60 min; And / or, the temperature at which the positive electrode active material and the electrolyte are mixed is 20°C to 30°C; And / or, the linear velocity of mixing the premix and the binder is from 5 m / s to 20 m / s; And / or, the mixing time of the premix and the binder is 20 min to 60 min; And / or, the temperature at which the premix and the binder are mixed is between 5°C and 20°C; And / or, the temperature of the fiberization treatment is 60°C to 80°C; And / or, the linear velocity of the fiberization process is 40 m / s to 60 m / s; And / or, the fiberization treatment time is 10 min to 30 min; And / or, the thinning temperature is between 80°C and 120°C.

10. An all-solid-state battery, characterized in that, At least including: The positive electrode sheet is selected from the all-solid-state positive electrode sheet according to claim 8, or the all-solid-state positive electrode sheet obtained by the preparation method according to claim 9; Negative electrode sheet; A solid electrolyte layer is disposed between the positive electrode and the negative electrode.

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