Electrode spray printing ink for solid-state batteries and method of making same, electrode layer

Abstract

The application relates to the technical field of inorganic solid-state batteries, in particular to electrode spray printing ink for solid-state batteries and a preparation method thereof, and an electrode layer, the preparation method comprising the following steps: providing a sol containing sulfide solid electrolyte nanoparticles; mixing a suspension liquid obtained by mixing electrode active particles and a dispersing agent with the sol containing the sulfide solid electrolyte nanoparticles to obtain the electrode spray printing ink. The nanoscale sulfide solid electrolyte particles are used to effectively fill the pores between the electrode active particles, and the contact between the particles is significantly improved; sintering between the nanoparticles can be realized at a lower temperature, and densification of the electrode layer is achieved. Meanwhile, the sulfide solid electrolyte nanoparticles in the electrode ink play the roles of ion transmission medium and inorganic binder.

Description

Technical Field

[0001] This invention relates to the field of inorganic solid-state battery technology, and in particular to an electrode spray printing ink for solid-state batteries, its preparation method, and an electrode layer. Background Technology

[0002] The widespread application of secondary batteries in mobile electronic devices, electric vehicles, and smart grids has placed higher demands on battery energy density and safety. Developing all-solid-state secondary batteries by replacing flammable organic electrolytes with inorganic electrolytes is one of the key technological approaches to meeting the performance requirements of these energy storage devices. Among them, inorganic all-solid-state batteries using sulfide solid electrolytes as ion transport materials have advantages such as high stability, good safety, and a wide operating temperature range, making them highly promising for application.

[0003] Currently, the mainstream technology for fabricating sulfide-based inorganic all-solid-state electrodes is slurry coating. For example, patent document CN104380502A discloses an electrode slurry for sulfide-based solid-state batteries and an electrode coating technology based on this slurry; the slurry consists of electrode active particles, sulfide solid electrolyte particles, a fluoropolymer binder, and a solvent as a dispersion medium; the binder volume percentage is 1.5%-10%; if the binder percentage is too low, the electrode structure is prone to cracking and collapse, while if the percentage is too high, it affects the electrode ion conductivity; conventional all-solid-state battery electrode slurries cannot completely eliminate the negative impact of the binder on electrode conductivity. In addition, when assembling batteries with coated electrodes, a 4.3 ton / m² pressure is required. 2 The pressure is increased to achieve electrode densification, but this pressure is much greater than the pressure used in the rolling process of lithium-ion batteries, which increases the complexity of the process.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide an electrode spray printing ink for solid-state batteries, a method for preparing the ink, and an electrode layer thereof, in order to solve the problems of poor battery performance and complex processes caused by the presence of binders in the slurry used to make all-solid-state electrodes and the need to apply pressure during assembly.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing electrode spray printing ink for solid-state batteries includes the following steps:

[0008] Provides sols containing sulfide solid electrolyte nanoparticles;

[0009] The electrode active particles are mixed with a dispersant to obtain a suspension;

[0010] The sol containing sulfide solid electrolyte nanoparticles is mixed with the suspension to obtain electrode spray printing ink.

[0011] The method for preparing electrode spray printing ink for solid-state batteries, wherein the particle size of the sulfide solid electrolyte nanoparticles is less than 50 nm; and the particle size of the electrode active particles is less than 100 μm.

[0012] The method for preparing electrode spray printing ink for solid-state batteries includes a suspension containing a conductive agent; the conductive agent is selected from one or more of acetylene black, Ketjen conductive carbon black, carbon fiber, and carbon nanotubes.

[0013] The method for preparing electrode spray printing ink for solid-state batteries, wherein, based on the solid phase, the sulfide solid electrolyte nanoparticles account for 10wt%-70wt%, the electrode active particles account for 10wt%-80wt%, and the conductive agent accounts for 0wt%-30wt%.

[0014] The method for preparing electrode spray printing ink for solid-state batteries, wherein the electrode active particles are selected from one or more of lithium cobalt oxide, nickel-cobalt-manganese ternary cathode materials, lithium iron phosphate, sulfur, lithium sulfide, lithium titanate, HOPG, hard carbon, and soft carbon.

[0015] The method for preparing electrode spray printing ink for solid-state batteries, wherein the dispersant is a nonpolar solvent or aprotic polar solvent.

[0016] The method for preparing electrode spray printing ink for solid-state batteries, wherein the method for preparing the sol containing sulfide solid electrolyte nanoparticles includes the following steps:

[0017] A sol is provided, wherein the sol contains Li2S nanoparticles;

[0018] P2S5 and Li2S in a molar ratio of 2:1 to 1:2 are added to an aprotic polar solvent to react and obtain a Li2S-P2S5 solution or a Li2S-P2S5 emulsion.

[0019] The sol is mixed with the Li2S-P2S5 solution or Li2S-P2S5 emulsion to obtain the sol containing sulfide solid electrolyte nanoparticles.

[0020] The method for preparing electrode spray printing ink for solid-state batteries includes a sol containing a soluble component; the soluble component includes one or more of LiI, LiCl, and LiBr.

[0021] An electrode spray printing ink for solid-state batteries is prepared using the method for preparing the electrode spray printing ink for solid-state batteries.

[0022] An electrode layer is prepared by the following method: under an inert atmosphere, the electrode spray printing ink for solid-state batteries is printed onto a substrate by spray printing and then dried to obtain an electrode layer precursor.

[0023] The electrode layer precursor is sintered to obtain the electrode layer.

[0024] The electrode layer wherein the sintering temperature is 120℃-250℃ and the sintering time is 0.5h-5h.

[0025] Beneficial Effects: This invention provides an electrode spray printing ink for solid-state batteries, its preparation method, and an electrode layer. The preparation method of the electrode spray printing ink includes the following steps: providing a sol containing sulfide solid electrolyte nanoparticles; mixing electrode active particles with a dispersant to obtain a suspension; and mixing the sol containing sulfide solid electrolyte nanoparticles with the suspension to obtain the electrode spray printing ink. The electrode spray printing ink prepared by this method not only ensures that the particle size of the solid particles in the ink meets the requirements of spray printing, avoiding nozzle clogging due to excessively large particle size, but also utilizes the nano-sized sulfide solid electrolyte nanoparticles in the sol to effectively fill the pores between electrode active particles, significantly improving the contact between particles. Furthermore, the nanoparticles have a large number of highly active surfaces, which, combined with the extremely high lithium-ion diffusion coefficient of the sulfide solid electrolyte, allows for sintering between nanoparticles at a relatively low temperature, achieving electrode layer densification without the need for additional high pressure. Simultaneously, the sulfide solid electrolyte nanoparticles in the electrode ink act as both an ion transport medium and an inorganic binder. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process flow for preparing electrode spray printing ink for solid-state batteries according to the present invention.

[0027] Figure 2 This is a scanning electron microscope image of the sulfur electrode layer in Example 3;

[0028] Figure 3 The above are the charge-discharge curves of the Li2S all-solid-state batteries in Example 4 and Comparative Example 1. Detailed Implementation

[0029] This invention provides an electrode spray printing ink for solid-state batteries, its preparation method, and an electrode layer. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0031] Existing literature: Co-spray printing of LiFePO4 and PEO-Li 1.5 Al 0.5 Ge 1.5 (PO4)3 hybridelectrodes for all-solid state Li-ion battery applications, J. Mater. Chem. A, 2019, 7, 19094, discloses a technique for fabricating solid-state batteries using spray printing. First, two miscible solvents with different vapor pressures are mixed to disperse active particles, obtaining an electrode suspension. This electrode suspension is then spray-printed and dried to form a honeycomb porous structure. A PEO-LAGP composite electrolyte layer is then spray-printed onto the electrode layer, and the polymer electrolyte PEO is allowed to permeate into the pores of the electrode layer at 60°C. However, the low ionic conductivity of the polymer solid electrolyte in this technique limits the battery performance.

[0032] Based on this, such as Figure 1 As shown, the present invention provides a method for preparing electrode spray printing ink for solid-state batteries, comprising the following steps:

[0033] Step S10: Provide a sol containing sulfide solid electrolyte nanoparticles;

[0034] Step S20: Mix the electrode active particles with the dispersant to obtain a suspension;

[0035] Step S30: Mix the sol containing sulfide solid electrolyte nanoparticles with the suspension to obtain electrode spray printing ink.

[0036] In this embodiment, a sol containing sulfide solid electrolyte nanoparticles is mixed with the suspension to obtain electrode spray printing ink. The electrode spray printing ink prepared by this method not only ensures that the particle size of the solid particles in the electrode ink meets the requirements of spray printing and does not cause nozzle clogging due to excessive particle size, but also ensures that the pores between the electrode active particles can be effectively filled by the sulfide solid electrolyte nanoparticles.

[0037] Specifically, the sulfide solid electrolyte nanoparticles in the sol containing sulfide solid electrolyte nanoparticles prepared by the above method have a particle size reduced to a certain scale, which can provide a sufficiently high active surface. When mixed with a suspension and used as an electrode spray printing ink, the electrode layer can be prepared by using a spray printing process to achieve densification during low-temperature sintering under conditions of no external pressure and no binder.

[0038] In some embodiments, the sulfide solid electrolyte nanoparticles have a particle size of less than 50 nm; the electrode active particles have a particle size of less than 100 μm. Using sulfide solid electrolyte nanoparticles with a particle size of less than 50 nm in the electrode spray printing ink for solid-state batteries has two advantages: firstly, the fine solid electrolyte particles can effectively fill the pores between the electrode active particles, significantly improving the contact between them; secondly, the sulfide solid electrolyte nanoparticles have a large number of highly active surfaces, and combined with their extremely high lithium-ion diffusion coefficient, when the electrode layer is prepared by spray printing using this electrode spray printing ink, sintering between the nanoparticles can be achieved at a relatively low temperature, resulting in a denser electrode layer without the need for additional high pressure; furthermore, the sulfide solid electrolyte nanoparticles in the electrode spray printing ink act as both an ion transport medium and an inorganic binder. Meanwhile, the particle size of the electrode active particles was optimized, which not only ensured that the particle size of the solid particles in the electrode spray printing ink met the requirements of spray printing and would not cause nozzle clogging due to excessive particle size, but also ensured that the pores between the electrode active particles could be effectively filled by the sulfurized solid electrolyte nanoparticles.

[0039] In a preferred embodiment, the particle size of the electrode active particles is less than 20 μm; more preferably, the particle size of the electrode active particles is less than 5 μm.

[0040] In some embodiments, the suspension also contains a conductive agent but not a polymer binder; the conductive agent is selected from one or more of acetylene black, Ketjen conductive carbon black, carbon fiber, and carbon nanotubes. By adding a conductive agent to the suspension, the conductivity of the electrode spray printing ink can be improved, and after it is made into an electrode layer, the conductivity of the electrode layer is further improved.

[0041] In a preferred embodiment, the conductive agent is acetylene black and / or carbon nanotubes.

[0042] In some embodiments, the electrode spray-printed ink, based on the solid phase, comprises 10 wt%-70 wt% of the sulfide solid electrolyte nanoparticles, 10 wt%-80 wt% of the electrode active particles, and 0 wt%-30 wt% of the conductive agent. Specifically, the preferred mass percentage of each component depends on the type of active particles selected, and the solid content of the electrode spray-printed ink is less than 30 wt%.

[0043] In a preferred embodiment, the solid content of the electrode spray printing ink is less than 10 wt%; more preferably, the solid content of the electrode spray printing ink is between 1 wt% and 5 wt%.

[0044] In some embodiments, the electrode active particles are selected from, but are not limited to, lithium cobalt oxide (LiCoO2) and nickel-cobalt-manganese ternary cathode material (LiNi). x Co y Mn 1-x-y O2, lithium iron phosphate (LiFePO4), sulfur, lithium sulfide, lithium titanate (Li4Ti5O) 12 One or more of highly oriented graphite (HOPG), hard carbon, and soft carbon; the electrode active particles may also be selected from LiNbO3-modified lithium cobalt oxide and LiNbO3-modified nickel-cobalt-manganese ternary cathode material LiNi. x Co y Mn 1-x-y O2. Among them, lithium titanate Li4Ti5O 12 Highly oriented graphite (HOPG), hard carbon, and soft carbon are all negative electrode active particles.

[0045] It should be noted that both hard carbon and soft carbon are anode active materials. Soft carbon refers to amorphous carbon that can be graphitized at temperatures above 2500℃; hard carbon is pyrolytic carbon derived from polymers. Hard carbon is also difficult to graphitize at temperatures above 2500℃. Soft carbon anode materials have the advantages of a low and stable charge / discharge potential plateau, large charge / discharge capacity, high efficiency, and good cycle performance; while hard carbon has a stable structure, long charge / discharge cycle life, and better safety performance.

[0046] In some embodiments, the method for preparing the sol containing sulfide solid electrolyte nanoparticles includes the following steps:

[0047] Step S11: Provide a sol containing Li2S nanoparticles;

[0048] Step S12: Add P2S5 and Li2S in a molar ratio of 2:1-1:2 to an aprotic polar solvent to react and obtain a Li2S-P2S5 solution or a Li2S-P2S5 emulsion.

[0049] Step S13: Mix the sol with the Li2S-P2S5 solution or Li2S-P2S5 emulsion to obtain the sol containing sulfide solid electrolyte nanoparticles.

[0050] Furthermore, according to the principles of the present invention, it is anticipated that sulfide solid electrolyte nanoparticles prepared by other methods (e.g., high-speed ball milling of pre-synthesized solid electrolytes in a nonpolar solvent) can also be used in ink preparation.

[0051] In some embodiments, the dispersant is a nonpolar solvent or an aprotic polar solvent. Using a nonpolar solvent or an aprotic polar solvent as a dispersant for electrode active material particles will not dissolve the sulfide solid electrolyte nanoparticles in the sol containing sulfide solid electrolyte nanoparticles, nor will it react chemically with them.

[0052] In a preferred embodiment, the dispersant includes, but is not limited to, one of alkanes, aromatic hydrocarbons, nitriles, ethers, and lipids; specifically, the dispersant may be, but is not limited to, n-hexane, toluene, acetonitrile, tetrahydrofuran, or ethyl propionate. Such dispersants do not dissolve sulfide solid electrolyte nanoparticles and do not chemically react with sulfide solid nanoparticles, and are easily volatilized upon heating.

[0053] In some embodiments, the sol also contains a soluble component; the soluble component includes one or more of LiI, LiCl, and LiBr.

[0054] In some embodiments, in step S11, a sol of Li2S nanoparticles is prepared in a liquid dispersant by physical or chemical coagulation; then the sol is purified by centrifugation, dialysis and other techniques to remove reaction byproducts, and finally dispersed with an appropriate amount of aprotic solvent to obtain a sol containing Li2S nanoparticles.

[0055] In some embodiments, in step S12, P2S5 and Li2S are weighed in a molar ratio of 1:1, and then an appropriate amount of aprotic polar solvent such as nitrile, ester, or ether is added, and the mixture is stirred continuously until the reaction is complete. If there are solid impurities, they can be removed by filtration to obtain a Li2S-P2S5 solution or a Li2S-P2S5 emulsion.

[0056] In some embodiments, in step S13, the sol and the Li2S-P2S5 solution or Li2S-P2S5 emulsion are mixed so that the total molar ratio of Li2S to P2S5 in the sol containing sulfide solid electrolyte nanoparticles is between 70:30 and 80:20. After continuous stirring, a transparent or translucent precursor sol is obtained, that is, a sol containing sulfide solid electrolyte nanoparticles.

[0057] In some embodiments, in step S20, depending on the type of electrode active particles, the electrode active particles and the dispersant can be mixed by wet chemical method or mechanical wet milling to obtain a suspension.

[0058] In addition, the present invention also provides an electrode spray printing ink for solid-state batteries, which is prepared by the method for preparing the electrode spray printing ink for solid-state batteries.

[0059] In this embodiment, the electrode spray printing ink prepared by the preparation method does not contain binders, and when the electrode layer is prepared by spray printing, no external pressure needs to be applied, which saves process steps, and the resulting electrode layer has high battery performance.

[0060] In addition, the present invention also provides an electrode layer, which is prepared by the following method:

[0061] Step S100: Under an inert atmosphere, the electrode spray printing ink for solid-state batteries is printed onto the substrate using spray printing and then dried to obtain the electrode layer precursor.

[0062] Step S200: The electrode layer precursor is sintered to obtain the electrode layer.

[0063] In this embodiment, the electrode spray-printed ink is printed onto the substrate by spray printing. After drying and sintering, the electrode layer is obtained. The sulfide solid electrolyte nanoparticles in the electrode spray-printed ink act as both an ion transport medium and an inorganic binder. Therefore, the ionic conductivity inside the electrode is improved without the need to add additional polymer binders that do not have ion transport capabilities.

[0064] Specifically, the use of spray printing to prepare the electrode layer of inorganic solid-state electrodes is a manufacturing process suitable for mass production. At the same time, the replicability of spray printing makes it easy to fabricate solid-state batteries on curved or irregularly shaped surfaces.

[0065] In some embodiments, the sintering temperature is 120℃-250℃; the sintering time is 0.5h-5h; by utilizing the easy sintering characteristics of the sulfide solid electrolyte nanoparticles contained in the spray printing ink, the electrode layer can be densified by low-temperature sintering, thereby eliminating the use of binders that impair conductivity and improving the electrochemical performance of the electrode layer; and without the need to apply the pressure of hundreds of megapascals in conventional processes, the manufacturing process is simplified and the equipment requirements are reduced.

[0066] In a preferred embodiment, the sintering temperature is related to the selection of the dispersant, and the sintering time is 1-3 hours.

[0067] In some embodiments, in step S100, the substrate can be any surface with current-collecting function, including but not limited to copper foil, aluminum foil, nickel foil, stainless steel sheet, polyimide film with conductive coating, etc. Because printing has excellent replicability, the substrate can be a curved surface.

[0068] In some embodiments, in step S100, the spray printing refers to a printing method that involves atomizing ink and then spraying it onto a substrate. The atomization in spray printing can be achieved in various ways, such as ultrasonic spraying using ultrasonic oscillation to atomize the ink; or aerosol spray printing using high-speed airflow to atomize the ink.

[0069] In some embodiments, during step S100, when the electrode spray printing ink for solid-state batteries is printed onto the substrate using spray printing, the substrate may be heated to cause the solvent in the electrode spray printing ink to evaporate, thereby improving the initial density of the electrode layer and its adhesion to the substrate. The stable heating range of the substrate is 80°C-250°C, preferably related to the type of dispersant.

[0070] In some embodiments, the electrode spray printing ink for solid-state batteries is printed onto the substrate using spray printing under an inert atmosphere, which can solve the problems of hygroscopicity and oxidation of sulfurized solid electrolytes.

[0071] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0072] Example 1

[0073] This embodiment provides a sol containing sulfide solid electrolyte nanoparticles, and its preparation method is as follows:

[0074] Under an argon atmosphere, elemental sulfur was added to a 1 mol / L tetrahydrofuran solution of LiEt3BH according to the stoichiometric ratio. The mixture was stirred continuously until the reaction was complete. The reaction byproducts were removed by high-speed centrifugation to obtain Li2S sol.

[0075] Under an argon atmosphere, P2S5 and Li2S were weighed out in a molar ratio of 1:1, and an appropriate amount of tetrahydrofuran was added. The mixture was stirred continuously until a Li2S-P2S5 emulsion was obtained.

[0076] While maintaining continuous stirring of the Li2S sol, the Li2S-P2S5 emulsion was added dropwise to the Li2S sol, controlling the amount of Li2S-P2S5 solution added so that the overall molar ratio of Li2S to P2S5 after mixing was 75:25. After continuing stirring for 1 hour, a translucent sulfide solid electrolyte sol was obtained.

[0077] After the sol is dried to remove the free solvent, it needs to be heat-treated at 140℃ to completely remove tetrahydrofuran and obtain a sulfide solid electrolyte with ionic conductivity.

[0078] Example 2

[0079] This embodiment provides a sol containing sulfide solid electrolyte nanoparticles, and its preparation method is as follows:

[0080] Under an argon atmosphere, elemental sulfur was added to a 1 mol / L tetrahydrofuran solution of LiEt3BH according to the stoichiometric ratio. The mixture was stirred continuously until the reaction was complete. The reaction byproducts were removed by high-speed centrifugation to obtain Li2S sol.

[0081] Under an argon atmosphere, P2S5 and Li2S were weighed out in a molar ratio of 1:1, and an appropriate amount of acetonitrile was added. The mixture was stirred continuously until a clear Li2S-P2S5 solution was obtained.

[0082] While maintaining continuous stirring of the Li2S sol, the Li2S-P2S5 solution was added dropwise to the Li2S sol, controlling the amount of Li2S-P2S5 solution added so that the overall molar ratio of Li2S to P2S5 after mixing was 75:25. After continuing stirring for 1 hour, a transparent sulfide solid electrolyte sol was obtained.

[0083] To completely remove tetrahydrofuran and acetonitrile from the sol, the sol needs to undergo heat treatment at 250°C after drying to remove the free solvent, in order to obtain a sulfide solid electrolyte with ionic conductivity.

[0084] Example 3

[0085] Sublimed sulfur and acetylene black were mixed at a mass ratio of 3:2 and ball-milled at 500 rpm for 8 hours using zirconium oxide as the ball milling medium. Then, an appropriate amount of tetrahydrofuran was added, and the mixture was wet-milled at 300 rpm for 1 hour to obtain an SC suspension.

[0086] The suspension was mixed with the sulfide solid electrolyte sol prepared in Example 2 in a certain proportion to ensure that the mass ratio of sulfur, acetylene black and sulfide solid electrolyte was 3:2:5; by adding an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5wt%, thus obtaining electrode spray printing ink.

[0087] Electrode spray printing ink was applied to aluminum foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the aluminum foil temperature was maintained at 80°C to promote the evaporation of free solvents. The sprayed aluminum foil was then sintered at 140°C for 3 hours under an argon atmosphere to obtain a dense sulfur electrode layer loaded on the aluminum foil, as shown in the attached figure. Figure 2 As shown.

[0088] To test the electrochemical performance of the sulfur electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the negative electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂O₃) was used. + Using a 16-layer lithium TFSI (lithium salt) separator and a sulfur electrode layer sprayed onto aluminum foil as the positive electrode, the three layers are stacked and compressed under a pressure of approximately 1 MPa to form a button cell. This cell exhibits a specific capacity of approximately 1600 mAh / g (for sulfur) at 60°C and a 0.2C rate.

[0089] Example 4

[0090] Sulfur powder was added to a 1 mol / L tetrahydrofuran solution of LiEt3BH according to the stoichiometric ratio, and the mixture was stirred continuously until the reaction was complete to obtain a sol containing Li2S nanoparticles. After centrifugation to remove reaction byproducts, the Li2S nanoparticles were dispersed in an appropriate amount of tetrahydrofuran solvent, and an appropriate amount of carbon nanotubes was added to the sol.

[0091] Then, an appropriate amount of the sulfide solid electrolyte sol prepared in Example 2 was added to ensure that the mass ratio of Li2S, carbon nanotubes and sulfide solid electrolyte was 2:2:6; by adding an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5wt%, and electrode spray printing ink was obtained.

[0092] Electrode spray printing ink was applied to aluminum foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the aluminum foil temperature was maintained at 250°C to promote the evaporation of free solvents. The sprayed aluminum foil was then sintered under vacuum at 250°C for 1 hour to obtain a Li₂S electrode layer loaded on the aluminum foil.

[0093] To test the electrochemical performance of the Li₂S electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the negative electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂S) was used. + Using a 16-layer LiTFSI (lithium salt) separator and a Li2S electrode layer sprayed onto aluminum foil as the positive electrode, the three layers are stacked and compressed under a pressure of approximately 1 MPa to form a button cell. This cell exhibits a specific capacity of approximately 800 mAh / g (for Li2S) at 60°C and a 0.2C rate.

[0094] Example 5

[0095] Lithium iron phosphate and acetylene black were mixed at a mass ratio of 60:10, and an appropriate amount of toluene was added. The mixture was wet-milled at 300 rpm for 1 hour using zirconium oxide as the ball milling medium to obtain a lithium iron phosphate suspension. This suspension was then mixed with the sulfide solid electrolyte sol prepared in Example 1 at a specific ratio, ensuring that the mass ratio of lithium iron phosphate, acetylene black, and solid electrolyte was 60:10:30. By adding an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5 wt%, thus obtaining the electrode spray printing ink.

[0096] Electrode spray printing ink was applied to aluminum foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the aluminum foil temperature was maintained at 120°C to promote the evaporation of free solvents. The sprayed aluminum foil was then sintered at 140°C for 3 hours under an argon atmosphere to obtain a lithium iron phosphate electrode layer loaded on the aluminum foil.

[0097] To test the electrochemical performance of the lithium iron phosphate electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the negative electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂O₃) was used. + Using a lithium iron phosphate (LiTFSI) separator (=16, LiTFSI is lithium salt), and a lithium iron phosphate electrode layer sprayed on aluminum foil as the positive electrode, the three layers are stacked and compressed under a pressure of about 1 MPa to form a button cell. This cell has a specific capacity of approximately 150 mAh / g (for lithium iron phosphate) at 60°C and a 0.2C rate.

[0098] Example 6

[0099] LiNbO3-modified lithium cobalt oxide powder was added to an appropriate amount of n-hexane and wet-milled at 100 rpm for 1 hour using zirconium oxide as the ball milling medium to obtain a lithium cobalt oxide suspension. This suspension was then mixed with the sulfide solid electrolyte sol prepared in Example 1 at a specific ratio, ensuring a mass ratio of lithium cobalt oxide to sulfide solid electrolyte of 80:20. By adding an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5 wt%, thus obtaining the electrode spray printing ink.

[0100] Electrode spray printing ink was applied to aluminum foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the aluminum foil temperature was maintained at 80°C to promote the evaporation of free solvents. The sprayed aluminum foil was then sintered at 140°C for 3 hours under an argon atmosphere to obtain a lithium cobalt oxide electrode layer loaded on the aluminum foil.

[0101] To test the electrochemical performance of the lithium cobalt oxide electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the negative electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂O₃) was used. + Using a lithium iron phosphate (LiTFSI) separator (=16, LiTFSI being lithium salt), and a lithium iron phosphate electrode layer sprayed onto aluminum foil as the positive electrode, the three layers are stacked and compressed under a pressure of approximately 1 MPa to form a button cell. This cell exhibits a specific capacity of approximately 100 mAh / g (for lithium cobalt oxide) at 60°C and a 0.2C rate.

[0102] Example 7

[0103] LiNbO3-modified nickel-cobalt-manganese ternary cathode material LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2 powder and acetylene black were mixed at a mass ratio of 90:10, and an appropriate amount of ethyl propionate was added. The mixture was wet-milled at 100 rpm for 1 hour using zirconium oxide as the ball milling medium to obtain a nickel-cobalt-manganese ternary cathode material suspension. This suspension was then mixed with the sulfide solid electrolyte sol prepared in Example 1 at a specific ratio, ensuring that the mass ratio of the ternary cathode material, acetylene black, and sulfide solid electrolyte was 63:7:30. By adding an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5 wt%, thus obtaining the electrode spray printing ink.

[0104] Electrode spray printing ink was applied to aluminum foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the aluminum foil temperature was maintained at 110℃ to promote the evaporation of free solvents. The sprayed aluminum foil was then sintered at 140℃ for 3 hours under an argon atmosphere to obtain a ternary cathode material electrode layer loaded on the aluminum foil.

[0105] To test the electrochemical performance of the nickel-cobalt-manganese ternary electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the negative electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂O₃) was used. + Using a ternary cathode material (LiTFSI = 16, where LiTFSI is the lithium salt) as the separator, and a ternary cathode material electrode layer sprayed onto aluminum foil as the positive electrode, the three layers are stacked and compressed under a pressure of approximately 1 MPa to form a button cell. This battery exhibits a specific capacity of approximately 130 mAh / g (for the ternary cathode material) at 60°C and a 0.2C rate.

[0106] Example 8

[0107] Lithium titanate Li4Ti5O12 The powder and acetylene black were mixed at a mass ratio of 80:20, and an appropriate amount of n-hexane was added. The mixture was wet-milled at 300 rpm for 1 hour using zirconium oxide as the ball milling medium to obtain a lithium titanate suspension. This suspension was then mixed with the sulfide solid electrolyte sol prepared in Example 1 at a specific ratio, ensuring that the mass ratio of lithium titanate, acetylene black, and sulfide solid electrolyte was 40:10:50. By adding an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5 wt%, thus obtaining the electrode spray printing ink.

[0108] Electrode spray printing ink was applied to aluminum foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the aluminum foil temperature was maintained at 80°C to promote the evaporation of free solvents. The sprayed aluminum foil was then sintered at 140°C for 3 hours under an argon atmosphere to obtain a lithium titanate electrode layer loaded on the aluminum foil.

[0109] To test the electrochemical performance of the lithium titanate electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the counter electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂O₃) was used. + Using a lithium titanate (LiTFSI = 16) separator and a lithium titanate electrode layer sprayed onto aluminum foil as the working electrode, the three layers are stacked and compressed under a pressure of approximately 1 MPa to form a button cell. This cell exhibits a specific capacity of approximately 150 mAh / g (for lithium titanate) at 60°C and a 0.2C rate.

[0110] Example 9

[0111] Highly oriented graphite powder and acetylene black were mixed at a mass ratio of 48:2, and an appropriate amount of n-hexane was added. The mixture was wet-milled at 300 rpm for 1 hour using zirconium oxide as the ball milling medium to obtain a graphite suspension. This suspension was then mixed with the sulfide solid electrolyte sol prepared in Example 2 at a specific ratio, ensuring that the mass ratio of graphite, acetylene black, and sulfide solid electrolyte was 48:2:50. By adding an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5 wt%, thus obtaining the electrode spray printing ink.

[0112] Electrode spray printing ink was applied to nickel foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the nickel foil temperature was maintained at 150°C to promote the evaporation of free solvent. The sprayed nickel foil was then sintered at 250°C for 1 hour under an argon atmosphere to obtain a graphite electrode layer loaded on the nickel foil.

[0113] To test the electrochemical performance of the graphite electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the counter electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂O₃) was used. +Using a 16-layer lithium TFSI (lithium salt) separator and a graphite electrode layer sprayed onto nickel foil as the working electrode, the three layers are stacked and compressed under a pressure of approximately 1 MPa to form a button cell. This cell exhibits a specific capacity of approximately 280 mAh / g (for graphite) at 60°C and a 0.2C rate.

[0114] Comparative Example 1

[0115] According to the stoichiometric ratio, sulfur powder was added to a 1 mol / L tetrahydrofuran solution of LiEt3BH, and the mixture was stirred continuously until the reaction was complete to obtain a sol containing Li2S nanoparticles. After centrifugation to remove reaction byproducts, the Li2S nanoparticles were dispersed in an appropriate amount of tetrahydrofuran solvent. An appropriate amount of Ketjen conductive carbon black was added to the sol. Further, an appropriate amount of the sulfide solid electrolyte sol prepared in Example 2 was added to ensure that the mass ratio of Li2S, Ketjen conductive carbon black, and solid electrolyte was 2:2:6. By supplementing with an appropriate amount of tetrahydrofuran, the solid content in the mixture was made to be 5 wt%, thus obtaining electrode ink.

[0116] Electrode ink was sprayed onto aluminum foil using ultrasonic spraying under an argon atmosphere. During the spraying process, the aluminum foil temperature was maintained at 250°C to promote the evaporation of the free solvent. The sprayed aluminum foil was then sintered under vacuum at 250°C for 1 hour to obtain a Li2S electrode layer loaded on the aluminum foil.

[0117] To test the electrochemical performance of the Li₂S electrode, an all-solid-state battery was assembled using the following method: lithium metal was used as the negative electrode, and an 80 μm thick PEO polymer solid electrolyte (EO / Li₂S) was used. + Using a 16-layer LiTFSI (lithium salt) separator and a Li2S electrode layer sprayed onto aluminum foil as the positive electrode, the three layers are stacked and compressed under a pressure of approximately 1 MPa to form a button cell. This cell exhibits a specific capacity of approximately 600 mAh / g (for Li2S) at 60°C and a 0.2C rate.

[0118] However, because the conductive carbon black in Comparative Example 1 is more porous than the carbon nanotubes used in Example 4, the electrode layer prepared by spraying has a lower density, resulting in a larger overpotential in the battery compared to Example 4. Figure 3 As shown.

[0119] In summary, this invention provides an electrode spray printing ink for solid-state batteries, its preparation method, and an electrode layer. The preparation method of the electrode spray printing ink includes the following steps: providing a sol containing sulfide solid electrolyte nanoparticles; mixing electrode active particles with a dispersant to obtain a suspension; and mixing the sol containing sulfide solid electrolyte nanoparticles with the suspension to obtain the electrode spray printing ink. The electrode spray printing ink prepared by this method not only ensures that the particle size of the solid particles in the ink meets the requirements of spray printing, avoiding nozzle clogging due to excessively large particle size, but also utilizes the nano-sized sulfide solid electrolyte nanoparticles in the sol to effectively fill the pores between electrode active particles, significantly improving the contact between particles. Furthermore, the nanoparticles have a large number of highly active surfaces, which, combined with the extremely high lithium-ion diffusion coefficient of the sulfide solid electrolyte, allows for sintering between nanoparticles at a relatively low temperature, achieving electrode layer densification without the need for additional high pressure. Meanwhile, the sulfide solid electrolyte nanoparticles in the electrode ink serve as both an ion transport medium and an inorganic binder.

[0120] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing electrode spray printing ink for solid-state batteries, characterized in that, Including the following steps: Provides sols containing sulfide solid electrolyte nanoparticles; The electrode active particles are mixed with a dispersant to obtain a suspension; The sol containing sulfide solid electrolyte nanoparticles is mixed with the suspension to obtain electrode spray printing ink.

2. The method for preparing electrode spray printing ink for solid-state batteries according to claim 1, characterized in that, The sulfide solid electrolyte nanoparticles have a particle size of less than 50 nm; the electrode active particles have a particle size of less than 100 μm.

3. The method for preparing electrode spray printing ink for solid-state batteries according to claim 1, characterized in that, The suspension also contains a conductive agent; the conductive agent is selected from one or more of acetylene black, Ketjen conductive carbon black, carbon fiber, and carbon nanotubes.

4. The method for preparing electrode spray printing ink for solid-state batteries according to claim 3, characterized in that, The electrode spray printing ink, based on the solid phase, comprises 10wt%-70wt% of the sulfide solid electrolyte nanoparticles, 10wt%-80wt% of the electrode active particles, and 0wt%-30wt% of the conductive agent.

5. The method for preparing electrode spray printing ink for solid-state batteries according to claim 1, characterized in that, The electrode active particles are selected from one or more of lithium cobalt oxide, nickel-cobalt-manganese ternary cathode materials, lithium iron phosphate, sulfur, lithium sulfide, lithium titanate, HOPG, hard carbon, and soft carbon; and / or the dispersant is a nonpolar solvent or aprotic polar solvent.

6. The method for preparing electrode spray printing ink for solid-state batteries according to claim 1, characterized in that, The preparation method of the sol containing sulfide solid electrolyte nanoparticles includes the following steps: A sol is provided, wherein the sol contains Li2S nanoparticles; P2S5 and Li2S in a molar ratio of 2:1 to 1:2 are added to an aprotic polar solvent to react and obtain a Li2S-P2S5 solution or a Li2S-P2S5 emulsion. The sol is mixed with the Li2S-P2S5 solution or Li2S-P2S5 emulsion to obtain the sol containing sulfide solid electrolyte nanoparticles.

7. The method for preparing electrode spray printing ink for solid-state batteries according to claim 6, characterized in that, The sol also contains soluble components; the soluble components include one or more of LiI, LiCl, and LiBr.

8. An electrode spray printing ink for solid-state batteries, characterized in that, It is prepared using the method for preparing electrode spray printing ink for solid-state batteries as described in any one of claims 1-7.

9. An electrode layer, characterized in that, The electrode layer is prepared by the following method: under the protection of an inert atmosphere, the electrode spray printing ink for solid-state batteries as described in claim 8 is printed onto the substrate by spray printing, and then dried to obtain the electrode layer precursor. The electrode layer precursor is sintered to obtain the electrode layer.

10. The electrode layer according to claim 9, characterized in that, The sintering temperature is 120℃-250℃; the sintering time is 0.5h-5h.

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