All-solid-state battery and manufacturing method therefor

Abstract

The present invention relates to an all-solid-state battery and a manufacturing method therefor. More specifically, the inside of an electrode adjacent to a sulfide-based solid electrolyte membrane is solvent-free or a non-polar solvent is included in the electrode to reduce interfacial resistance between the sulfide-based solid electrolyte membrane and the electrode, thereby improving performance of the all-solid-state battery.

Description

All-solid-state battery and method for manufacturing the same

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0106058, filed August 14, 2023, and Korean Patent Application No. 10-2024-0104404, filed August 6, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an all-solid-state battery and a method for manufacturing the same.

[0003] Various batteries are being studied to overcome the limitations of current lithium secondary batteries in terms of battery capacity, safety, output, large-scale development, and miniaturization.

[0004] Representative examples include metal-air batteries with much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries with no risk of explosion in terms of safety, supercapacitors for output, NaS batteries or RFBs (redox flow batteries) for large-scale applications, and thin film batteries for miniaturization, all of which are being continuously researched in academia and industry.

[0005] All-solid-state batteries replace the liquid electrolytes used in conventional lithium secondary batteries with solid electrolytes. Because they do not use flammable solvents, they eliminate the risk of ignition or explosion caused by the decomposition of conventional electrolytes, significantly improving safety. Furthermore, because lithium metal or lithium alloys can be used as a cathode material, they offer the advantage of dramatically improving the battery's energy density relative to its mass and volume.

[0006] Research is ongoing to commercialize all-solid-state batteries using sulfide-based solid electrolytes, which have high ionic conductivity and ductile properties among solid electrolytes.

[0007] All-solid-state batteries containing a sulfide-based solid electrolyte are typically manufactured by inserting a sulfide-based solid electrolyte membrane between an anode and a cathode, followed by high-pressure pressing. To manufacture an all-solid-state battery comprising a cathode, a sulfide-based solid electrolyte membrane, and a cathode, a free-standing sulfide-based solid electrolyte membrane can generally be used, a sulfide-based solid electrolyte membrane can be transferred to an electrode, or a process of overcoating a sulfide-based solid electrolyte membrane onto an electrode can be performed. Among these, overcoating a sulfide-based solid electrolyte membrane onto an electrode has the advantage of increasing process efficiency and enabling the implementation of a thin-film solid electrolyte membrane.

[0008] However, when a sulfide-based solid electrolyte membrane is overcoated on an electrode, the solvent of the electrolyte slurry may penetrate the electrode, and at this time, small and light electrolyte particles or binders may be squeezed out and positioned at the interface between the electrode and the sulfide-based solid electrolyte membrane, which may cause an increase in interfacial resistance.

[0009] Therefore, when overcoating a sulfide-based solid electrolyte membrane on an electrode, there is a growing need for a technology that can prevent the phenomenon of the electrolyte slurry being squeezed and the solvent contained in the electrolyte slurry penetrating into the electrode.

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Japanese Patent No. 4046376

[0013] The present inventors have conducted various studies to solve the above problems and have confirmed that, in an all-solid-state battery including a positive electrode, a sulfide-based solid electrolyte membrane, and a negative electrode, when the positive electrode or the negative electrode to be overcoated by the sulfide-based solid electrolyte membrane is impregnated with a non-polar solvent in advance and then dried to become solvent-free or to contain a residual non-polar solvent, the phenomenon of the solvent of the sulfide-based solid electrolyte slurry used in the overcoating being squeezed into the positive electrode or the negative electrode and permeating therein is prevented, thereby reducing the interfacial resistance between the electrode and the electrolyte and improving the battery performance.

[0014] Accordingly, the purpose of the present invention is to provide an all-solid-state battery in which the interfacial resistance between the positive or negative electrode and the sulfide-based solid electrolyte membrane is reduced, thereby improving battery performance.

[0015] Another object of the present invention is to provide a method for manufacturing the all-solid-state battery.

[0016] In order to achieve the above object, the present invention provides an all-solid-state battery including a positive electrode, a negative electrode, and a sulfide-based solid electrolyte membrane interposed therebetween, wherein a positive electrode active material layer or a negative electrode active material layer included in the positive electrode or negative electrode is solvent-free or includes a non-polar solvent, and the dielectric constant of the non-polar solvent is 10 or less.

[0017] In one embodiment of the present invention, the nonpolar solvent may include at least one selected from the group consisting of toluene, xylene, anisole, benzene, hexane, heptane, nonane, decane, dibromomethane, dichloromethane, chloroform, butyrate, and acetate.

[0018] In one embodiment of the present invention, the non-polar solvent may be included in an amount of 100 to 2000 ppm.

[0019] In one embodiment of the present invention, the sulfide-based solid electrolyte membrane may include a sulfide-based solid electrolyte having an argyrodite structure.

[0020] In one embodiment of the present invention, the sulfide-based solid electrolyte is Li 7-x PS 6-x A x (At this time, A may be Cl, Br, I, Sn or a combination thereof, and x may include 0≤x≤2).

[0021] In one embodiment of the present invention, the negative active material layer may include lithium metal or may include a non-cathode coating layer.

[0022]

[0023] The present invention also provides a method for manufacturing an all-solid-state battery, comprising: (a) a step of impregnating a positive electrode active material layer or a negative electrode active material layer included in a positive electrode or a negative electrode with a non-polar solvent; (b) a step of overcoating a slurry for forming a sulfide-based solid electrolyte membrane on the positive electrode active material layer or the negative electrode active material layer obtained in step (a) to form a sulfide-based solid electrolyte membrane; and (c) a step of drying the sulfide-based solid electrolyte membrane obtained in step (b); wherein the dielectric constant of the non-polar solvent is 10 or less.

[0024] In one embodiment of the present invention, the slurry for forming the sulfide-based solid electrolyte membrane may be prepared by mixing the sulfide-based solid electrolyte into a solvent.

[0025] In one embodiment of the present invention, the solvent may be a non-polar solvent, and the dielectric constant of the non-polar solvent may be 10 or less.

[0026] In one embodiment of the present invention, the slurry may further include a binder.

[0027] In one embodiment of the present invention, the coating may be performed by bar coating, roll coating, gravure coating, doctor blade coating, slot die coating, slurry coating, or extrusion coating.

[0028] In one embodiment of the present invention, the drying in step (c) may be performed at 40°C to 90°C.

[0029] According to the present invention, in an all-solid-state battery formed by overcoating a sulfide-based solid electrolyte membrane on a positive electrode or a negative electrode, the inside of the positive electrode or the negative electrode is solvent-free, or a non-polar solvent is contained inside the positive electrode or the negative electrode, so that the solvent of the slurry used in the overcoating of the sulfide-based solid electrolyte membrane is squeezed and prevented from penetrating into the inside of the positive electrode or the negative electrode. Accordingly, fine particles of components included in the slurry squeezed together with the solvent are also not squeezed, so that the phenomenon of the fine particles accumulating at the interface can be prevented. In addition, since such fine particles do not accumulate at the interface between the positive electrode or the negative electrode and the sulfide-based solid electrolyte membrane, the interfacial resistance is reduced, so that the performance of the all-solid-state battery can be improved.

[0030] Figure 1 is a photograph showing the results of an experiment to select a solvent that does not cause a side reaction with a sulfide-based solid electrolyte in a test example of the present invention.

[0031] FIG. 2 is a scanning electron microscope (SEM) photograph of the interface between the non-cathode coating layer and the sulfide-based solid electrolyte membrane in the all-solid-state battery manufactured in Example 1 and Comparative Example 1 of the present invention.

[0032] It can be manufactured by forming. For example, methods such as pressing, coating, and deposition can be used. In addition, a case in which a battery is assembled without a lithium thin film on the negative electrode current collector and a metallic lithium thin film is formed on the metal plate by initial charging is also included in the negative electrode of the present invention.

[0033]

[0034] In one embodiment of the present invention, the positive electrode included in the all-solid-state battery includes a positive electrode active material layer, and the positive electrode active material layer may be formed on one surface of the positive electrode current collector.

[0035] The above positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder. In addition, the positive electrode active material layer may additionally include a sulfide-based solid electrolyte.

[0036] In addition, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions, and examples thereof include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and Li[Ni x Co y Mn z M v ]O2 (wherein M is one or two or more elements selected from the group consisting of Al, Ga, and In; 0.3≤x<1.0, 0≤y, z≤0.5, 0≤v≤0.1, x+y+z+v=1), Li(Li a M b-a-b' M' b' )O 2-c A c (In the above formula, 0≤a≤0.2, 0.6≤b≤1, 0≤b'≤0.2, 0≤c≤0.2; M includes at least one selected from the group consisting of Mn and Ni, Co, Fe, Cr, V, Cu, Zn and Ti; M' is at least one selected from the group consisting of Al, Mg and B, and A is at least one selected from the group consisting of P, F, S and N.) layered compounds or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented by MyO2 (wherein, M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and y is 0.01 to 0.3); chemical formula LiMn 2-y My Lithium manganese composite oxides represented by O2 (wherein M is Co, Ni, Fe, Cr, Zn or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., but are not limited thereto.

[0037] In addition, the positive electrode active material may be included in an amount of 60 to 90 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 60 wt%, 65 wt% or more, or 70 wt% or more, and may be 80 wt% or less, 85 wt% or less, or 90 wt% or less. If the content of the positive electrode active material is less than 60 wt%, battery performance may deteriorate, and if it is more than 90 wt%, mass transfer resistance may increase.

[0038] In addition, the binder is as described above for the cathode.

[0039] In addition, the above-mentioned conductive material is as described above for the above-mentioned cathode.

[0040] In addition, the specific type of material of the sulfide-based solid electrolyte may be the same as the description of the sulfide-based solid electrolyte included in the above-described sulfide-based solid electrolyte membrane. However, the content of the sulfide-based solid electrolyte in the positive electrode active material layer may be 5 to 25 wt%, taking into account the ion conductivity characteristics, and specifically, may be 5 wt% or more, 8 wt% or more, or 10 wt% or more, and may be 15 wt% or less, 20 wt% or less, or 25 wt% or less.

[0041] In addition, the positive electrode current collector supports the positive electrode active material layer and serves to transfer electrons between the external conductor and the positive electrode active material layer.

[0042] The positive electrode current collector is not particularly limited as long as it has high electronic conductivity without causing chemical changes in the all-solid-state battery. For example, the positive electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or an aluminum-cadmium alloy.

[0043] The above-mentioned positive electrode current collector may have a finely irregular structure on its surface or may employ a three-dimensional porous structure to strengthen the bonding strength with the positive electrode active material layer. Accordingly, the positive electrode current collector may include various forms such as a film, sheet, foil, mesh, net, porous body, foam, or non-woven fabric.

[0044] The positive electrode as described above can be manufactured according to a conventional method, and specifically, a composition for forming a positive electrode active material layer prepared by mixing a positive electrode active material, a conductive agent, and a binder in an organic solvent phase is applied and dried on a positive electrode current collector, and optionally, to improve electrode density, it can be manufactured by compression molding the positive electrode current collector. At this time, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, binder, and conductive agent and is easily evaporated. Specifically, examples thereof include acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, and the like.

[0045]

[0046] Method for manufacturing an all-solid-state battery

[0047] The present invention also relates to a method for manufacturing an all-solid-state battery.

[0048] Another method for manufacturing an all-solid-state battery according to the present invention comprises the steps of: (a) impregnating a positive electrode active material layer or a negative electrode active material layer included in a positive electrode or a negative electrode with a non-polar solvent; (b) overcoating a slurry for forming a sulfide-based solid electrolyte membrane on the positive electrode active material layer or the negative electrode active material layer obtained in step (a) to form a sulfide-based solid electrolyte membrane; and (c) drying the sulfide-based solid electrolyte membrane obtained in step (b). The non-polar solvent may have a dielectric constant of 1 to 10.

[0049]

[0050] Hereinafter, the method for manufacturing an all-solid-state battery according to the present invention will be described in more detail step by step.

[0051] The types, properties and weights of the materials included in the positive electrode, negative electrode and sulfide-based solid electrolyte membrane of the above-mentioned all-solid-state battery manufacturing method are the same as those described above.

[0052]

[0053] In one embodiment of the present invention, in step (a), a non-polar solvent may be impregnated into the positive electrode active material layer or negative electrode active material layer included in the positive electrode or negative electrode.

[0054] The above positive electrode can be manufactured by applying a slurry for forming a positive electrode active material layer on a positive electrode current collector and drying it.

[0055] Additionally, the negative electrode can be manufactured by applying a slurry for forming a negative electrode active material layer on a negative electrode current collector and drying it. The negative electrode active material layer can be a non-cathode coating layer that does not contain a negative electrode active material.

[0056] The method for impregnating the positive electrode active material layer or negative electrode active material layer with a non-polar solvent is not particularly limited as long as it is a method that can impregnate the positive electrode active material layer or negative electrode active material layer by spraying the non-polar solvent. For example, an appropriate amount of the non-polar solvent can be sprayed onto the positive electrode active material layer or negative electrode active material layer using a micro pipette or sprayer to impregnate the positive electrode active material layer or negative electrode active material layer.

[0057]

[0058] In one embodiment of the present invention, in step (b), a slurry for forming a sulfide-based solid electrolyte membrane may be overcoated on the positive electrode active material layer or negative electrode active material layer obtained in step (a) to form a sulfide-based solid electrolyte membrane.

[0059] The slurry for forming the above sulfide-based solid electrolyte membrane is prepared by mixing sulfide-based solid electrolyte particles and a solvent, wherein the solvent may be a non-polar solvent having a dielectric constant of 1 to 10. The non-polar solvent may include at least one selected from the group consisting of butyrate, acetate, xylene, and anisole. The slurry may be prepared so that the solid content is 45 to 60 wt%.

[0060] In addition, when manufacturing the slurry for forming the above sulfide-based solid electrolyte membrane, a binder may be additionally mixed to improve the bonding force and mechanical properties.

[0061] In addition, the coating method for performing the above overcoating may be bar coating, roll coating, gravure coating, doctor blade coating, slot die coating, slurry coating, or extrusion coating, but is not limited thereto as long as it is a coating method that can be commonly performed in the art.

[0062]

[0063] In one embodiment of the present invention, in step (c), the sulfide-based solid electrolyte membrane obtained in step (b) can be dried.

[0064] The drying may be performed at a temperature of 40°C to 90°C. Specifically, the drying temperature may be 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, or 60°C or higher, or 70°C or lower, 75°C or lower, 80°C or lower, 85°C or lower, or 90°C or lower. If the drying temperature is lower than 40°C, the amount of residual solvent may become excessive, and if it exceeds 90°C, binder denaturation may occur due to the high drying temperature.

[0065]

[0066] After a sulfide-based solid electrolyte film is formed on the positive electrode active material layer or negative electrode active material layer in this manner, an all-solid-state battery can be manufactured by laminating and pressurizing the negative electrode or positive electrode on the other side of the sulfide-based solid electrolyte film.

[0067] The pressurization may be performed within a range of pressure that does not cause deformation or damage to the anode, the sulfide-based solid electrolyte membrane, and the cathode, within which good bonding between them is possible. For example, the pressure during the pressurization may be 300 MPa to 700 MPa, and specifically, the pressure during the pressurization may be 300 MPa or more, 350 MPa or more, or 400 MPa or more, and may be 600 MPa or less, 650 MPa or less, or 700 MPa or less. If the pressure during the pressurization is less than 300 MPa, the interfacial resistance between the anode or the cathode and the sulfide-based solid electrolyte membrane may increase, and if it exceeds 700 MPa, the anode, the cathode, or the sulfide-based solid electrolyte membrane may be deformed or damaged.

[0068]

[0069] battery module

[0070] The present invention also relates to a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.

[0071] Hereinafter, specific examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system. Hereinafter, preferred embodiments are presented to help understand the present invention, but the following embodiments are only illustrative of the present invention and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it will be apparent that such changes and modifications also fall within the scope of the appended patent claims.

[0072] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0073]

[0074] Cathode impregnation process Sulfide-based solid electrolyte membrane formation method Content of non-polar solvent remaining in the cathode after drying (ppm) Solvent Impregnation Name Dielectric constant Example 1 BB5○Overcoating 443 Comparative example 1--XOvercoating 32 Comparative example 2 EC85○Overcoating 0 Comparative example 3 BB5XTransfer 7 Note 1) BB: butyrate Note 2) EC: ethylene carbonate

[0075]

[0076] Test Example: Selection of a solvent that does not cause side reactions with sulfide-based solid electrolytes

[0077] An experiment was conducted to identify a solvent that does not cause a side reaction with a sulfide-based solid electrolyte as a solvent for impregnating an electrode adjacent to a sulfide-based solid electrolyte membrane.

[0078] Li6PS5Cl, a sulfide-based solid electrolyte, was dispersed in the nonpolar solvent butyrate (BB) and the polar solvent ethylene carbonate (EC), respectively, and color changes were observed. No color change indicates no side reaction, while a color change indicates a side reaction.

[0079]

[0080] Figure 1 is a photograph showing the results of an experiment to select a solvent that does not cause a side reaction with a sulfide-based solid electrolyte in a test example of the present invention.

[0081] Referring to Figure 1, it was confirmed that the sulfide-based solid electrolyte powder (①) did not show any color change when dispersed in butyrate (BB), a non-polar solvent (②), and showed a color change when dispersed in ethylene carbonate (EC), a polar solvent (③).

[0082] From this, it was confirmed that butyrate (BB), a nonpolar solvent, does not cause a side reaction with the sulfide-based solid electrolyte, and is therefore a suitable solvent for impregnating the electrode adjacent to the sulfide-based solid electrolyte membrane in an all-solid-state battery.

[0083]

[0084] Example 1

[0085] (1) Cathode manufacturing

[0086] A slurry for forming a cathode-free coating layer was prepared by mixing carbon black as a conductive agent and PVDF (polyvinylidene fluoride) as a binder with NMP (N-Methyl-2-pyrrolidone) solvent. At this time, the conductive agent and binder were used at a weight ratio of 90:10, and the slurry was prepared to have a solid content of 45 wt%.

[0087] The slurry for forming the above-mentioned cathode-free coating layer was coated on one side of a stainless steel (SS) substrate, and then vacuum dried at 100°C for 10 hours to form a cathode-free coating layer.

[0088] The nonpolar solvent, butyrate (BB, dielectric constant: 5), was sprayed onto the nonpolar coating layer using a micropipette to wet it, thereby impregnating the nonpolar solvent into the nonpolar coating layer.

[0089]

[0090] (2) Formation of sulfide-based solid electrolyte membrane by overcoating

[0091] A slurry for forming a sulfide-based solid electrolyte membrane was prepared by mixing Li6PS5Cl having an argyrodite structure as a sulfide-based solid electrolyte and acrylonitrile butadiene rubber (NBR) as a binder in a weight ratio of 90:10 with butyrate, a nonpolar solvent, so that the solid content was 50 wt%.

[0092] The slurry for forming the above sulfide-based solid electrolyte membrane was applied onto the non-cathode coating layer, overcoated with a bar coater, and then vacuum-dried at 70°C for 5 hours to form a sulfide-based solid electrolyte membrane.

[0093]

[0094] (3) All-solid-state battery manufacturing

[0095] After stacking the positive electrode on the above sulfide-based solid electrolyte membrane, an all-solid-state battery was manufactured by pressurizing it at a pressure of 600 MPa. The positive electrode was made of a positive electrode active material (LiN 0.8 Co 0.1 Mn 0.1O2, NCM 811), conductive material (carbon fiber), sulfide-based solid electrolyte (Li6PS5Cl), and binder (polytetrafluoroethylene, PTFE) were mixed in a weight ratio of 84:0.2:14.8:1, and a positive electrode active material layer containing the mixture was applied to an Al foil, which is a positive electrode current collector, and rolled to manufacture a positive electrode. The content of the non-polar solvent remaining in the negative electrode was 443 ppm.

[0096]

[0097] Comparative Example 1

[0098] The same procedure as Example 1 was followed, except that the non-polar solvent was not impregnated into the cathode-free coating layer. The content of the non-polar solvent remaining in the cathode was 32 ppm.

[0099]

[0100] Comparative Example 2

[0101] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the non-polar coating layer was impregnated with ethylene carbonate (EC, dielectric constant 85), a polar solvent, instead of butyrate, a non-polar solvent. Due to a side reaction between the polar solvent and the overcoated sulfide-based solid electrolyte membrane, it was impossible to evaluate battery performance and measure the solvent content.

[0102]

[0103] Comparative Example 3

[0104] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the non-cathode coating layer was prepared without being impregnated with a non-polar solvent, the slurry for forming the sulfide-based solid electrolyte membrane was formed on a PET substrate, and then the non-cathode coating layer and the sulfide-based solid electrolyte membrane were bonded by applying pressure. The bonding allowed a transfer process to proceed, so that a sulfide-based solid electrolyte membrane was formed on the non-cathode coating layer. At this time, the non-cathode coating layer was not exposed to a non-polar solvent. The content of the residual non-polar solvent was 7 ppm.

[0105]

[0106] Experimental Example 1

[0107] For the all-solid-state batteries manufactured in the examples and comparative examples, the content of residual non-polar solvent contained in the negative electrode was compared.

[0108] After manufacturing the all-solid-state battery, the content of non-polar solvent remaining in the non-cathode coating layer of the anode was measured using Headspace GC / FID (Headspace Gas Chromatography with Flame Ionization Detection) analysis. The sample for solvent measurement was configured to include the anode, cathode, and the sulfide-based solid electrolyte membrane formed by overcoating between them.

[0109]

[0110] As shown in Table 1 above, Example 1 was measured to have a relatively large amount of residual non-polar solvent in the cathode compared to Comparative Examples 1 to 3.

[0111] In Comparative Example 1, although the process of impregnating the non-polar solvent into the cathode-free coating layer was not performed, residual non-polar solvent was measured. This is due to the non-polar solvent used in the slurry preparation when forming the sulfide-based solid electrolyte membrane through overcoating.

[0112] In addition, Comparative Example 2 is a case where a polar solvent was impregnated into the non-polar coating layer instead of the cathode coating layer, and it was impossible to evaluate battery performance and measure the solvent content due to a side reaction between the polar solvent and the overcoated sulfide-based solid electrolyte membrane.

[0113] In addition, in Comparative Example 3, a non-polar coating layer and a sulfide-based solid electrolyte membrane were formed separately and then bonded together without impregnating the non-polar coating layer with a non-polar solvent, and a small amount of residual non-polar solvent was measured. The small amount of residual non-polar solvent in the cathode was contained in the sulfide-based solid electrolyte membrane.

[0114]

[0115] Experimental Example 2

[0116] In the all-solid-state batteries manufactured in Example 1 and Comparative Example 1, the interface between the non-anode coating layer and the sulfide-based solid electrolyte membrane was observed. The interface was observed using a scanning electron microscope (SEM, JEOL, IT-800).

[0117] Figure 2 is an SEM photograph of the interface between the non-cathode coating layer and the sulfide-based solid electrolyte membrane in the all-solid-state battery manufactured in Example 1 and Comparative Example 1 of the present invention.

[0118] Referring to FIG. 2, it can be seen that, compared to Example 1, Comparative Example 1 has a large number of fine particle lumps (30) at the interface between the cathode-free coating layer (10) and the sulfide-based solid electrolyte membrane (20). These fine particle lumps are accumulated at the interface during the process of overcoating the slurry when forming the sulfide-based solid electrolyte membrane, when the components of the slurry are squeezed and try to penetrate the cathode-free coating layer. The components of the slurry accumulated at the interface may mainly be small and light electrolyte fine particles, binders, etc.

[0119] On the other hand, in Example 1, it is difficult to observe such fine particles at the interface, because the non-polar solvent butyrate (BB) was impregnated into the cathode-free coating layer of Example 1, which prevented the components of the slurry from being squeezed and penetrating into the cathode-free coating layer.

[0120] Meanwhile, in Comparative Example 2, a polar solvent, ethylene carbonate (EC), was used instead of the nonpolar solvent, butyrate (BB), used in Example 1. However, a side reaction occurred between the polar solvent, ethylene carbonate (EC), impregnated in the non-cathode coating layer, and the sulfide-based solid electrolyte membrane overcoated on the non-cathode coating layer, resulting in decomposition, making it impossible to conduct an experiment to observe the interface.

[0121]

[0122] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0123]

[0124] [Explanation of symbols]

[0125] 10: Non-polar coating layer

[0126] 20: Sulfide electrolyte membrane

[0127] 30: Particulate matter lump

Claims

1. In an all-solid-state battery including a positive electrode, a negative electrode, and a sulfide-based solid electrolyte membrane interposed therebetween, The positive electrode active material layer or negative electrode active material layer included in the positive electrode or negative electrode is solvent-free or contains a non-polar solvent, An all-solid-state battery, wherein the dielectric constant of the non-polar solvent is 10 or less.

2. In paragraph 1, An all-solid-state battery, wherein the non-polar solvent comprises at least one selected from the group consisting of toluene, xylene, anisole, benzene, hexane, heptane, nonane, decane, dibromomethane, dichloromethane, chloroform, butyrate, and acetate.

3. In paragraph 1, An all-solid-state battery, wherein the non-polar solvent is contained in an amount of 100 to 2000 ppm.

4. In paragraph 1, An all-solid-state battery, wherein the above sulfide-based solid electrolyte membrane includes a sulfide-based solid electrolyte having an argyrodite structure.

5. In paragraph 1, The above sulfide-based solid electrolyte is Li 7-x PS 6-x A x (wherein, A is Cl, Br, I, Sn or a combination thereof, and x is 0≤x≤2), an all-solid-state battery.

6. In paragraph 1, An all-solid-state battery, wherein the negative active material layer comprises lithium metal or a non-cathode coating layer. 7.(a) A step of impregnating a non-polar solvent into a positive electrode active material layer or a negative electrode active material layer included in a positive electrode or a negative electrode; (b) a step of forming a sulfide-based solid electrolyte membrane by overcoating a slurry for forming a sulfide-based solid electrolyte membrane on the positive electrode active material layer or negative electrode active material layer obtained in step (a); and (c) a step of drying the sulfide-based solid electrolyte membrane obtained in step (b); including, A method for manufacturing an all-solid-state battery, wherein the dielectric constant of the above non-polar solvent is 10 or less.

8. In paragraph 7, A method for manufacturing an all-solid-state battery, wherein the slurry for forming the above sulfide-based solid electrolyte membrane is manufactured by mixing a sulfide-based solid electrolyte with a solvent.

9. In paragraph 8, The above solvent is a nonpolar solvent, A method for manufacturing an all-solid-state battery, wherein the dielectric constant of the above non-polar solvent is 10 or less.

10. In paragraph 8, A method for manufacturing an all-solid-state battery, wherein the above slurry further includes a binder.

11. In paragraph 7, A method for manufacturing an all-solid-state battery, wherein the above overcoating is performed by bar coating, roll coating, gravure coating, doctor blade coating, slot die coating, slurry coating, or extrusion coating.

12. In paragraph 7, A method for manufacturing an all-solid-state battery, wherein the drying in step (c) is performed at a temperature of 40°C to 90°C.

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