Binder for the positive electrode of a solid-state battery, composite positive electrode containing the same, and solid-state battery

Abstract

The present invention relates to a binder for a positive electrode of an all-solid-state battery, a composite positive electrode containing the binder, and an all-solid-state battery.

Description

[Technical Field]

[0001] The present invention relates to a binder for the positive electrode of an all-solid-state battery, a composite positive electrode containing the same, and an all-solid-state battery.

[0002] This application claims priority rights under Korean Patent Application No. 10-2023-0117967 dated September 5, 2023, and Korean Patent Application No. 10-2024-0117383 dated August 30, 2024, and incorporates all the contents disclosed in the documents of said Korean Patent Applications as part of this Specification. [Background technology]

[0003] A secondary battery is a device that stores external electrical energy in the form of chemical energy and generates electricity when needed. Because it can be recharged many times, it is also called a rechargeable battery. Commonly used secondary batteries include lead-acid batteries, nickel-cadmium batteries (NiCd), nickel-metal hydride batteries (NiMH), and lithium-ion batteries. Secondary batteries offer both economic and environmental advantages compared to primary batteries, which are used once and then discarded.

[0004] Meanwhile, with the development of wireless communication technology, there is a growing demand for lighter, thinner, and smaller portable devices and automotive accessories, and for rechargeable batteries used as energy sources for these devices. In particular, from the perspective of preventing environmental pollution, hybrid and electric vehicles have become practical, and research is emerging to reduce manufacturing costs and weight and extend the lifespan of these next-generation automotive batteries by using rechargeable batteries. Among the various types of rechargeable batteries, lithium-ion batteries, which are lightweight, exhibit high energy density and operating potential, and have a long cycle life, have recently been attracting attention.

[0005] Generally, lithium secondary batteries are manufactured by mounting an electrode assembly, consisting of a negative electrode, a positive electrode, and a separator membrane, inside a cylindrical or rectangular metal can or an aluminum laminate sheet pouch-type case, and then injecting an electrolyte into the electrode assembly.

[0006] Conventionally, liquid electrolytes, in which lithium salts are dissolved in non-aqueous organic solvents, have been primarily used as electrolytes for lithium secondary batteries. However, such liquid electrolytes have a high probability of electrode material degradation and organic solvent volatilization, as well as the risk of combustion or explosion due to rising ambient and battery temperatures, and leakage, making it difficult to realize various types of lithium secondary batteries with high safety.

[0007] On the other hand, all-solid-state batteries, which use solid electrolytes, have the advantage of being able to manufacture electrode assemblies safely and simply because they eliminate organic solvents.

[0008] However, in order to manufacture the positive electrode used in all-solid-state batteries, a polymer binder that can effectively bind the positive electrode components is essential, and a commonly known polymer binder is nitrile rubber-based binder material. However, when an all-solid-state battery is manufactured using a nitrile rubber-based binder as the polymer binder, there is a problem in that the interfacial adhesion between the current collector and the electrode and the battery life are reduced.

[0009] Therefore, there is a need to develop a cathode binder that improves the mechanical properties of the electrode and increases its lifespan. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Republic of Korea Published Patent No. 10-2020-0063467 [Patent Document 2] Republic of Korea Published Patent No. 10-2020-0023308 [Non-patent literature]

[0011] [Non-Patent Document 1] Journal of the Electrochemical Society,164,A2075(2017) [Non-Patent Document 2] ACS Energy Letters 4, 94 (2018) [Non-Patent Document 3] Ecomat, 4(4), e12193 (2022) [Summary of the Invention] [Problem to be Solved by the Invention]

[0012] Accordingly, the present inventors conducted multifaceted research to solve the aforementioned problem, and as a result, confirmed that when a terpolymer polymer containing repeating units derived from ethylene, repeating units derived from methyl acrylate, and repeating units derived from glycidyl methacrylate is applied as a binder for a positive electrode, the adhesive force between the current collector and the electrode interface and the adhesive force inside the electrode can be improved, whereby a battery with improved life characteristics can be produced, and thus the present invention was completed.

[0013] Accordingly, an object of the present invention is to provide a binder for a positive electrode that improves the adhesive force between the current collector and the electrode interface and the adhesive force inside the electrode.

[0014] Another object of the present invention is to provide a composite positive electrode including the aforementioned binder for a positive electrode with improved life characteristics, and an all-solid-state battery including the same. Technical Solution

[0015] In one aspect of the present invention, the composite positive electrode includes a positive electrode active material, a conductive material, a solid electrolyte, and a polymer binder, and the polymer binder may be a terpolymer polymer containing repeating units derived from ethylene, repeating units derived from methyl acrylate, and repeating units derived from glycidyl methacrylate.

[0016] The polymer binder may include a terpolymer polymer containing a repeating unit represented by the following Chemical Formula 1, a repeating unit represented by the following Chemical Formula 2, and a repeating unit represented by the following Chemical Formula 3:

[0017] [Chem.]

[0018] [ka]

[0019] [ka]

[0020] In the above chemical formulas 1 to 3, p, q, and r are the number of moles in the repeating unit, respectively. p, q, and r are each independent integers between 1 and 100.

[0021] The polymer binder may be a polymer containing cross-repeating units represented by the following chemical formula 4:

[0022] [ka]

[0023] In the aforementioned chemical formula 4, A is a repeating unit represented by the aforementioned chemical formula 1, B is a repeating unit represented by the aforementioned chemical formula 2, and C is a repeating unit represented by the aforementioned chemical formula 3.

[0024] In the aforementioned chemical formula 4, the molar ratio of p:q for 1 mole of r may be 30-50:1-5.

[0025] In the aforementioned chemical formula 4, p:q:r may be 40:4:1.

[0026] In one aspect of the present invention, the polymer binder content is 3% by weight or less based on the total weight of the composite cathode, thereby providing a composite cathode.

[0027] In one aspect of the present invention, there is provided a composite cathode wherein the cathode active material comprises a lithium transition metal composite oxide, and the transition metal comprises one or more selected from the group consisting of Co, Mn, Ni and Al.

[0028] In one aspect of the present invention, there is provided a composite cathode wherein the lithium transition metal composite oxide comprises at least one compound represented by the following Chemical Formula 5: [Chemical Formula 5] Li x Ni a Co b Mn cmz O y In Chemical Formula 5, 0.5≤x≤1.5, 0≤a≤1, 0≤b<1, 0≤c<1, 0≤z<1, 1.5<y<5, a+b+c+z is 1 or less, and M comprises one or more selected from Al.

[0029] In one aspect of the present invention, there is provided a composite cathode wherein the solid electrolyte is a sulfide-based solid electrolyte.

[0030] In one aspect of the present invention, there is provided a composite cathode wherein the sulfide-based solid electrolyte comprises one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS.

[0031] In one aspect of the present invention, there is provided an all-solid-state battery comprising the composite cathode, an anode, and a solid electrolyte interposed therebetween. [Advantageous Effects of Invention]

[0032] The present invention, by including a ternary copolymer polymer containing repeating units derived from ethylene, repeating units derived from methyl acrylate, and repeating units derived from glycidyl methacrylate as a polymer binder, enhances the binding strength of the composite cathode and improves the adhesion between the current collector and electrode interface, as well as the adhesion within the electrode.

[0033] Furthermore, the inclusion of the ternary copolymer polymer has the effect of improving the lifespan characteristics of the all-solid-state battery. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic diagram illustrating the manufacturing process of composite cathodes for all-solid-state batteries. [Figure 2] This figure shows the X-ray powder diffraction (XRD) patterns of a solid electrolyte and a mixture of a solid electrolyte and a binder according to one embodiment of the present invention. [Figure 3] This figure shows the nanoindentation curves of composite cathodes according to one embodiment and a comparative example of the present invention. [Figure 4] This diagram shows a schematic SAICAS diagram and measurement results of a composite cathode according to one embodiment and a comparative example of the present invention. [Figure 5] This diagram shows a schematic representation of a nanoscratch of a composite cathode according to one embodiment and a comparative example of the present invention, as well as the measurement results. [Figure 6] This figure shows the GITT analysis results of a composite cathode according to one embodiment and a comparative example of the present invention. [Figure 7] This figure shows the ionic conductivity of a composite solid electrolyte and an image of a composite solid electrolyte sheet according to one embodiment and a comparative example of the present invention. [Figure 8] This is a diagram showing the initial charge and discharge curves of an all-solid-state battery according to one embodiment of the present invention. [Figure 9] This is a diagram showing the discharge capacity of an all-solid-state battery according to one embodiment of the present invention, based on the number of cycles. [Figure 10] This figure shows the first charge-discharge curve of an all-solid-state battery according to one embodiment and a comparative example of the present invention. [Figure 11] This figure shows a curve illustrating the CV electrochemical stability evaluation curve of a composite solid electrolyte sheet according to one embodiment of the present invention. [Figure 12] This diagram shows the discharge capacity of an all-solid-state battery by cycles according to one embodiment and a comparative example of the present invention. [Figure 13] This diagram shows the discharge capacity of an all-solid-state battery according to one embodiment and a comparative example of the present invention, based on current. [Figure 14] These images show cross-sections of a composite cathode before and after cycling according to one embodiment and a comparative example of the present invention. [Modes for carrying out the invention]

[0035] The present invention will be described in more detail below.

[0036] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their conventional or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best describe their invention.

[0037] The terms used in this invention are used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as “includes” or “having” should be understood as specifying the presence of features, figures, stages, operations, components, parts, or combinations thereof as described in the specification, and not as preemptively excluding the possibility of the presence or addition of one or more other features, figures, stages, operations, components, parts, or combinations thereof.

[0038] Lithium-ion batteries have been used in small devices such as mobile phones and laptops, but recently their applications have expanded to medium and large-scale devices such as electric vehicles and energy storage systems. In these cases, unlike small devices, the operating environment is harsher, and more batteries are required, so it is necessary to ensure stability as well as superior performance.

[0039] Most lithium-ion batteries currently on the market use a liquid electrolyte in which lithium salt is dissolved in an organic solvent. Because the organic solvent contained in the liquid electrolyte is highly volatile and flammable, there is a potential risk of ignition or explosion, and leakage may occur, resulting in a lack of long-term reliability.

[0040] Therefore, development is underway on all-solid-state batteries, which replace the liquid electrolyte of lithium secondary batteries with a solid electrolyte. All-solid-state batteries do not contain volatile organic solvents, thus eliminating the risk of explosion or fire. They are attracting attention as batteries that offer excellent economic efficiency and productivity, and can be manufactured with high output.

[0041] To achieve high energy density in all-solid-state batteries, it is essential to manufacture a polymer binder that can effectively bind the positive electrode components. Conventionally, widely known nitrile rubber-based binder materials have been used for the polymer binders for the positive electrodes, but these have problems such as reduced interfacial adhesion between the current collector and the electrodes, and reduced battery life.

[0042] Therefore, the present invention aims to provide a positive electrode binder that improves the mechanical properties of the electrode and increases its lifespan.

[0043] The configuration and effects of the present invention will be described in detail below.

[0044] In one embodiment of the present invention, the composite cathode comprises a cathode active material, a conductive material, a solid electrolyte, and a polymer binder, wherein the polymer binder comprises a ternary copolymer polymer.

[0045] The ternary copolymer polymer may contain repeating units derived from ethylene, repeating units derived from methyl acrylate, and repeating units derived from glycidyl methacrylate.

[0046] The aforementioned ternary copolymer polymer may contain repeating units represented by the following chemical formula 1, repeating units represented by the following chemical formula 2, and repeating units represented by the following chemical formula 3:

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] In the above chemical formulas 1 to 3, p, q, and r are the number of moles in the repeating unit, respectively. p, q, and r are each independent integers between 1 and 100.

[0051] The aforementioned ternary copolymer polymer may be a polymer containing cross-repeating units represented by the following chemical formula 4:

[0052] [ka]

[0053] In the aforementioned chemical formula 4, A is a repeating unit represented by the aforementioned chemical formula 1, B is a repeating unit represented by the aforementioned chemical formula 2, and C is a repeating unit represented by the aforementioned chemical formula 3.

[0054] In the aforementioned chemical formula 4, the molar ratio of p:q to 1 mole of r may be 30 to 50:1 to 5. For example, the molar ratios of p, q, and r may be 30:5:1, 40:5:1, 50:5:1, 30:4:1, 40:4:1, 50:4:1, 30:3:1, 40:3:1, 50:3:1, 30:2:1, 40:2:1, 50:2:1, 30:1:1, 40:1:1, 50:1:1, but are not limited to these examples.

[0055] As the molar ratio of p to r decreases relative to the molar ratio of q, the flexibility imparted to the polymer binder decreases, and the resistance of the positive electrode active material to volume fluctuations decreases. In other words, this leads to a decrease in the capacity preservation rate when evaluating cycle life, and also to a decrease in formation cycle discharge capacity.

[0056] As the molar ratio of r increases relative to the molar ratio of q, the molar ratio of q decreases relatively, leading to a decrease in binding strength. In other words, the binding ability decreases, resulting in a decrease in formation cycle discharge capacity and a decrease in cycle capacity preservation rate.

[0057] If the molar ratio of p to r is less than 30 based on a 1-5 molar ratio of q, the flexibility imparted to the polymer binder decreases, leading to a problem of brittleness during electrode manufacturing. Also, if the molar ratio of p is less than 10 based on a 1-5 molar ratio of q, the relative molar ratio of q increases, increasing the polarity of the polymer itself, resulting in a problem of insolubility in low-polarity solvents during electrode manufacturing. The low-polarity solvent may be butyl butyrate.

[0058] When the molar ratio of p to 1 mole of r exceeds 50 based on a 1-5 mole ratio of q, the binding force imparted to the polymer binder decreases, leading to a problem of desorption between the current collector and the positive electrode composite.

[0059] For every mole of r, the molar ratio of p is preferably 30 to 50, based on a molar ratio of 1 to 5 moles of q. More preferably, the molar ratio of p:q for every mole of r may be 40:4.

[0060] In the molar ratios of p, q, and r, if the molar ratio of q exceeds 5 based on a 30-50 molar ratio of p, the relative molar ratio of q increases, increasing the polarity of the polymer itself, which leads to the problem of it not being soluble in low-polarity solvents when manufacturing electrodes. The low-polarity solvent may be butyl butyrate.

[0061] In the above-mentioned p, q, and r, if r is 0, there are difficulties in battery manufacturing due to a decrease in flexibility and bonding strength imparted to the polymer binder.

[0062] In one embodiment of the present invention, the composite cathode contains a polymer binder in an amount of 3% by weight or less based on the total weight of the composite cathode. If the polymer binder content exceeds 3% by weight based on the total weight of the composite cathode, the binding ability is improved, but the content of the solid electrolyte that acts as a lithium ion transport pathway within the composite cathode decreases, which restricts the smooth movement of lithium ions within the electrode and increases resistance. In other words, if the polymer binder content exceeds 3% by weight based on the total weight of the composite cathode, lithium ions cannot move smoothly within the electrode, resulting in a problem of a continuous decrease in charge and discharge capacity.

[0063] Specifically, the content of the polymer binder may be 3.0% by weight or less, 2.5% by weight or less, 2.0% by weight or less, or 0.5% by weight or more, 1.0% by weight or more, or 1.5% by weight or more, based on the total weight of the composite cathode.

[0064] In one embodiment of the present invention, the solid electrolyte may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may include a solid electrolyte containing sulfur (S) and having ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table.

[0065] The sulfide-based solid electrolyte may include one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, but is not limited to these examples.

[0066] In the present invention, the average particle size of the sulfide-based solid electrolyte may be adjusted to a range suitable for all-solid-state batteries. In one specific embodiment of the present invention, the solid electrolyte may have an average particle size of 0.1 μm to 10 μm. More specifically, the solid electrolyte may have an average particle diameter of 0.1 μm or more, 0.5 μm or more, 1.0 μm or more, 1.5 μm or more, 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, 3.5 μm or more, 4.0 μm or more, 4.5 μm or more, 5.0 μm or more, or 10 μm or less, 9.5 μm or less, 9.0 μm or less, 8.5 μm or less, 8.0 μm or less, 7.5 μm or less, 7.0 μm or less, 6.5 μm or less, 6.0 μm or less, 5.5 μm or less, or 5.0 μm or less, but is not limited to these examples.

[0067] Furthermore, in one embodiment of the present invention, the selected solid electrolyte is 1 × 10 -5 S / cm, preferably 1 × 10 -3 It has an ionic conductivity of S / cm or higher.

[0068] In one embodiment of the present invention, the solid electrolyte layer may be manufactured, for example, by the following method.

[0069] First, prepare the solid electrolyte. The solid electrolyte may be obtained as a commercially available product or prepared by the following method. The solid electrolyte may be prepared by the following method.

[0070] First, LiCl, Li2S and P2S5 are mixed in stoichiometric amounts, and milled by a method such as a planetary ball mill to obtain a homogeneous mixture. The target Li6PS5Cl solid electrolyte can be obtained by subjecting the mixture to high-temperature heat treatment for a predetermined time. Said heat treatment can be performed at about 550°C, and the heat treatment time may be about 8 hours.

[0071] Next, the solid electrolyte material is added into and dispersed in a predetermined organic solvent to prepare a slurry, which is applied onto a release plate or the like, and dried to be molded into a sheet. If necessary, a solid electrolyte layer can be obtained by pressing the resulting sheet-shaped product.

[0072] In one embodiment of the present invention, the positive electrode active material is lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), chemical formula Li 1+x Mn 2-x O4 (wherein x is 0 to 0.33, for example, LiMn2O4), lithium manganese oxides such as LiMnO3, LiMn2O3, and LiMnO2, lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV2O4, V2O5, and Cu2V2O7, chemical formula LiNi 1-x M x O2 (wherein M is Co, Mn, Al, Cu, Fe, Mg, B or Ga, and 0<x<1), represented by Ni-site type lithium nickel oxide, for example, LiNi 1-z (Co, Mn, Al) z O2 (0<z<1); chemical formula LiMn 2-x M x O4 (wherein M is Co, Ni, Fe, Cr, Zn or Ta, and x is 0.01 to 1, for example, LiMn 1.5 Ni 0.5a lithium manganese composite oxide represented by O4) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiMn2O4 in which part of lithium in the chemical formula is replaced by alkaline earth metal ions; a disulfide compound; may contain one or a mixture of two or more selected from Fe2(MoO4)3 and lithium iron phosphate (LiFePO4). In one embodiment of the present invention, for improving electrical conductivity, all or at least part of the surface of active material particles of the lithium iron phosphate may be coated with a carbon material.

[0073] Preferably, the positive electrode active material is Lithium Nickel Cobalt Manganese Oxide (for example, Li(Ni,Co,Mn)O2, LiNi 1-z (Co, Mn, Al) z O2 (0<z<1)), Lithium Iron Phosphate (for example, LiFePO4 / C), Lithium Nickel Manganese Spinel (for example, LiNi 0.5 Mn 1.5 O4), Lithium Nickel Cobalt Aluminium Oxide (for example, Li(Ni,Co,Al)O2), Lithium Manganese Oxide (for example, LiMn2O4) and Lithium Cobalt Oxide (for example, LiCoO2), and may contain one or more selected from the above.

[0074] In the present invention, most preferably, the positive electrode active material contains a lithium transition metal composite oxide, and the transition metal may contain one or more of Co, Mn, Ni and Al.

[0075] In one embodiment of the present invention, the lithium transition metal composite oxide may contain at least one or more compounds represented by the following chemical formula 5.

[0076] [Chemical Formula 5] Li x Ni a Co b Mn c M z O y In the above Chemical Formula 5, 0.5≦x≦1.5, 0≦a≦1, 0≦b<1, 0≦c<1, 0≦z<1, 1.5<y<5, a+b+c+z is 1 or less, and M comprises one or more species selected from Al.

[0077] In a specific embodiment of the present invention, the positive electrode conductive material may be, for example, any one selected from the group consisting of graphite, carbon black, carbon fiber or metal fiber, metal powder, conductive whiskers, conductive metal oxides, activated carbon and polyphenylene derivatives, or a mixture of two or more of these conductive materials. More specifically, it may be one or a mixture of two or more conductive materials selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate and titanium oxide.

[0078] The current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity; for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or materials obtained by surface-treating the surface of aluminum or stainless steel with carbon, nickel, titanium, silver or the like can be used.

[0079] In one embodiment of the present invention, the solid electrolyte contained in the positive electrode may comprise one or more types selected from polymeric solid electrolytes, oxide-based solid electrolytes, and sulfide-based solid electrolytes. In one embodiment of the present invention, the positive electrode active material may preferably comprise the sulfide-based solid electrolyte described for the solid electrolyte above.

[0080] In one embodiment of the present invention, it is preferable that the positive electrode active material is present in the positive electrode at an amount of 70% by weight or more relative to 100% by weight of the positive electrode active material layer. Furthermore, it is preferable that the solid electrolyte is present in the positive electrode at an amount of 10% to 30% by weight relative to 100% by weight of the positive electrode active material layer.

[0081] On the other hand, in one specific embodiment of the present invention, the positive electrode is 5 mAh / cm². 2 More than 6mAh / cm 2 Above 10mAh / cm², or 10mAh / cm² 2 The load (per electrode area) may exceed the above limits.

[0082] In the battery according to the present invention, even when such a high-load positive electrode is applied, the battery can be operated at an electrochemically stable level.

[0083] On the other hand, in one specific embodiment of the present invention, the positive electrode active material layer can be obtained by casting a slurry produced by adding a positive electrode active material, a conductive material, a binder resin, and a solid electrolyte to a suitable solvent.

[0084] The present invention will be further described below with reference to examples, but these examples are for illustrative purposes only and the scope of the present invention is not limited thereto. Examples of the present invention are provided to give a more complete explanation of the present invention to a person of average knowledge in the industry.

[0085] Manufacturing Example 1: Production of EMG ternary copolymer polymer binder The polymer binder according to the present invention produced a ternary copolymer (hereinafter referred to as "EMG ternary copolymer") containing repeating units derived from ethylene, repeating units derived from methyl acrylate, and repeating units derived from glycidyl methacrylate.

[0086] To initiate a nickel enolate catalyst-based reaction during the polymerization process, a 0.02% by weight nickel enolate catalyst solution was prepared by pre-mixing trifluoromethane ligand precursor (Sigma-Aldrich) and Ni(COD)2 (COD=1,5-cyclooctadiene) (Sigma-Aldrich) in 30 ml of toluene solvent for 15 minutes. Subsequently, glycidyl methacrylate (C) (manufactured by Sigma-Aldrich) was dissolved in toluene at a concentration of 1.6 M. Methyl methacrylate (TCI) (B) and glycidyl methacrylate (C) (manufactured by Sigma-Aldrich) were dissolved in toluene in a molar ratio of 4:1. Then, the prepared nickel enolate catalyst solution and methylaluminoxane (manufactured by Sigma-Aldrich) co-catalyst were added. Subsequently, by adjusting the flow rate of ethylene gas, ethylene groups (A) in the polymer were injected with glycidyl methacrylate (C) (manufactured by Sigma-Aldrich) in a molar ratio of 40:1 to produce an EMG ternary copolymer. The reaction was terminated by adding methanol to the reactor.

[0087] To increase the yield through sufficient activation of the catalyst, the polymerization reaction was maintained at 55°C via a temperature-regulating water flow between the inner and outer jackets of a Buchi autoclave (manufactured by Buchiglas), and the internal pressure was maintained at approximately 4 atmospheres while ethylene gas was supplied.

[0088] Manufacturing Example 2 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 30:4:1.

[0089] Manufacturing Example 3 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 50:4:1.

[0090] Comparative Example 1 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 10:4:1.

[0091] Comparative Example 2 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 60:4:1.

[0092] Comparative Example 3 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 5:4:1.

[0093] Comparative Example 4 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 40:4:0.

[0094] Comparative Example 5 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 40:20:1.

[0095] Comparative Example 6 An EMG ternary copolymer was produced in the same manner as in Production Example 1, except that the molar ratio of the ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) was 20:40:1.

[0096] Experimental Example 1: Comparison of electrode manufacturing methods using repeated unit molar ratios for EMG ternary copolymer binders In the EMG ternary copolymer produced by Manufacturing Example 1, the copolymer produced by Comparative Example 1, in which the molar ratio of ethylene groups (A) was significantly reduced, exhibited reduced flexibility and brittleness during electrode manufacturing. When the manufactured electrode was subjected to physical folding stress, unlike electrodes with sufficient flexibility, the positive electrode composite fragmented and cracked. Therefore, the copolymer produced by Comparative Example 1 presented difficulties in manufacturing all-solid-state battery electrodes.

[0097] Furthermore, in the EMG ternary copolymer produced in Production Example 1, when the copolymer produced in Comparative Example 2, in which the molar ratio of ethylene groups (A) was significantly increased, the adhesive strength as a polymer binder decreased, and desorption occurred between the current collector and the positive electrode composite. Therefore, when the copolymer produced in Comparative Example 2 was included, the decrease in adhesive strength made it difficult to manufacture all-solid-state battery electrodes.

[0098] Furthermore, in the case of copolymers according to Comparative Examples 3, 5, and 6, the increasing molar ratio of methyl acrylate (B) to ethylene group (A) increased the polarity of the polymer itself, preventing it from dissolving in butyl butyrate, a low-polarity solvent for electrode manufacturing, making it difficult to manufacture all-solid-state battery electrodes.

[0099] Furthermore, in the case of the copolymer according to Comparative Example 4, it was confirmed that the adhesive strength decreased because the composite peeled off at the electrode edge when the electrodes were punched out for battery manufacturing, due to the absence of glycidyl methacrylate (C). It was also confirmed that the flexibility decreased because the surface of the composite was formed to be somewhat rough. Therefore, when the copolymer according to Comparative Example 4 was included, it was difficult to manufacture all-solid-state battery electrodes.

[0100] Therefore, in the production of a composite cathode containing an EMG ternary copolymer and an all-solid-state battery containing it, it was confirmed that the most appropriate method is to produce a copolymer with a molar ratio of ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) of 30-50:1-5:1.

[0101] Experimental Example 2: Comparison of electrode manufacturing methods using the molar ratio of repeating units and EMG ternary copolymer binder. The formation cycle discharge capacity and capacity preservation rate of the EMG ternary copolymers produced by Production Examples 1 to 3 were evaluated based on the molar ratio of ethylene groups (A). The results for the discharge capacity and capacity preservation rate are shown in Table 1 below.

[0102] [Table 1]

[0103] As shown in Table 1 above, in the case of the copolymer produced by Production Example 2, in which the molar ratio of ethylene groups (A) was reduced compared to the EMG ternary copolymer produced by Production Example 1, the flexibility as a polymer binder decreased, and the resistance to volume fluctuations of the active material decreased. This caused a decrease in the capacity preservation rate when evaluating the cycle life, and it was confirmed that the formation cycle discharge capacity also decreased compared to Production Example 1.

[0104] Furthermore, in the case of the copolymer produced by Production Example 3, in which the molar ratio of ethylene groups (A) was increased compared to the EMG ternary copolymer produced by Production Example 1, it was clearly observed that the binding strength decreased and the binding ability declined due to the relative decrease in the molar ratio of methyl acrylate (B) to ethylene groups (A), resulting in a decrease in formation cycle discharge capacity. It was also confirmed that the cycle capacity preservation rate decreased compared to Production Example 1.

[0105] Therefore, in the production of a composite cathode containing an EMG ternary copolymer and an all-solid-state battery containing the same, it was confirmed that a composite cathode containing a copolymer with a molar ratio of ethylene group (A), methyl acrylate (B), and glycidyl methacrylate (C) of 40:4:1 improves the mechanical properties of the electrode and maintains a high lifespan.

[0106] Example 1: Composite cathode with EMG ternary copolymer binder and all-solid-state battery with the same LiRing 0.9 Co 0.05 Mn 0.05 A slurry was prepared by mixing O2, Li6PS5Cl(LPSCl) powder (manufactured by Posco JK Solid Solution), Super C (manufactured by Timcal), and the EMG ternary copolymer prepared in Production Example 1 in butyl butyrate solvent. The slurry was mixed in a Thinky Mixer (manufactured by Thinky) for 15 minutes and cast onto an aluminum current collector with a doctor blade to produce a composite cathode. The mass ratio of the cathode active material, solid electrolyte, conductive material, and binder in the produced composite cathode was 75:21.5:1.5:2. The produced composite cathode had an active material content of 15 mg / cm² per unit area. 2 It was manufactured under this load.

[0107] After placing 100 mg of Li6PS5Cl powder into a PET mold and pressurizing it at room temperature under a pressure of 300 MPa to produce Li6PS5Cl pellets, the manufactured composite positive electrode was placed inside and pressurized under a pressure of 430 MPa. Li-In foil (Lithium (manufactured by Honjo Corporation), Indium (manufactured by Nilaco Corporation)) was placed on the opposite side of the Li6PS5Cl pellets, and the assembly was fastened under a pressure of 60 MPa to produce an all-solid-state battery.

[0108] Example 2 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the mass ratio of the positive electrode active material, solid electrolyte, conductive material, and binder in the composite positive electrode was 75:22.5:1.5:1.

[0109] Example 3 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the mass ratio of the positive electrode active material, solid electrolyte, conductive material, and binder in the composite positive electrode was 75:20.5:1.5:3.

[0110] Comparative Example 7 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the mass ratio of the positive electrode active material, solid electrolyte, conductive material, and binder in the composite positive electrode was 75:19.5:1.5:4.

[0111] Experimental Example 3: Comparison of electrode manufacturing methods based on polymer binder content In the all-solid-state batteries described in Examples 1 and 3 and Comparative Example 7, the formation cycle discharge capacity and capacity preservation rate of the batteries were evaluated based on the binder content in the composite positive electrode. The results of the discharge capacity and capacity preservation rate are shown in Table 2 below.

[0112] [Table 2]

[0113] As shown in Table 2 above, the higher the content of polymer binder in the electrode, the lower the content of solid electrolyte acting as a lithium ion transport pathway. This restricts the smooth movement of lithium within the electrode, increasing resistance. Therefore, although the binding ability improves with increasing binder content, the movement of lithium ions within the composite cathode is hindered, preventing smooth lithium ion movement within the electrode and resulting in a sustained decrease in the battery's charge and discharge capacity.

[0114] Therefore, it was confirmed that the batteries according to Examples 1 and 3, which have a polymer binder content of 3% by weight or less, exhibit superior cycle discharge capacity and capacity retention compared to the battery according to Comparative Example 7, which has a polymer binder content exceeding 3% by weight.

[0115] Comparative Example 8: Composite cathode using nitrile-butadiene rubber and all-solid-state battery using the same LiRing 0.9 Co0.05 Mn 0.05 A slurry was prepared by mixing O2, Li6PS5Cl (LPSCl) powder, Super C, and nitrile-butadiene rubber (manufactured by Kumho Petro Chemical) in butyl butyrate solvent. The slurry was mixed for 15 minutes in a Thinky Mixer (manufactured by Thinky), and a composite cathode was produced by casting it onto an aluminum current collector with a doctor blade. The mass ratio of the cathode active material, solid electrolyte, conductive material, and binder in the produced composite cathode was 75:21.5:1.5:2. The produced composite cathode had an active material content of 15 mg / cm² per unit area. 2 It was manufactured under this load.

[0116] After placing 100 mg of Li6PS5Cl powder into a PET mold and pressurizing it at room temperature under a pressure of 300 MPa to produce Li6PS5Cl pellets, the prepared composite cathode was placed inside and pressurized under a pressure of 430 MPa. After placing Li-In foil on the opposite side of the Li6PS5Cl pellets, the assembly was fastened under a pressure of 60 MPa to produce an all-solid-state battery.

[0117] Experimental Example 4: Evaluation of the chemical stability of a composite cathode using an EMG ternary copolymer binder. XRD evaluation was performed to assess the chemical stability of the composite cathode manufactured in Example 1, and the results are shown in Figure 2.

[0118] The presence or absence of side reactions between the butyl butyrate solvent and the EMG ternary copolymer binder used in the composite cathode manufacturing process was confirmed, and the method is as follows: First, solutions were prepared by reacting LPSCl solid electrolyte with butyl butyrate solvent for 24 hours, and by mixing LPSCl solid electrolyte with an EMG ternary copolymer binder solution and reacting for 24 hours. After drying the solutions in a vacuum oven, XRD evaluation was performed on the remaining residues, and it was confirmed that the structural stability of the LPSCl solid electrolyte was well maintained in all compositions, as shown in Figure 2.

[0119] Experimental Example 5: Mechanical property evaluation of composite cathodes using EMG ternary copolymer binder (Nano Indenter) - Hardness measurement The hardness of the composite cathodes from Example 1 and Comparative Example 8 was measured. The evaluation was performed using a nanoindentation device, and the results are shown in Figure 3 below.

[0120] Specifically, the hardness was measured by using a nanoindenter (Anton Paar, NHT3) to press-fit the electrode specimen with an indenter (Vickers Indenter, tip width 0.5 μm). Specifically, the indenter was loaded onto the electrode specimen at a speed of 0.1 mN / s for 10 seconds, applying a maximum force of 1 mN, followed by 10 seconds of creep, and then the indenter was unloaded at a speed of 0.1 mN / s for 10 seconds, and the resulting press-fit hardness was measured.

[0121] The hardness measurements showed that the composite cathode of Example 1 exhibited a smaller penetration depth compared to the composite cathode of Comparative Example 8. Table 3 below shows the hardness of the composite cathodes.

[0122] [Table 3]

[0123] As shown in Table 3 above, it was confirmed that the composite cathode of Example 1, which contains EMG ternary copolymer, has higher hardness than the composite cathode of Comparative Example 8.

[0124] Experimental Example 6: Mechanical property evaluation of composite cathodes using EMG ternary copolymer binder (SAICAS) - Interfacial adhesion measurement The interfacial adhesion strength of the composite cathodes from Example 1 and Comparative Example 8 was measured. The evaluation was performed using a SAICAS (Surface and Interfacial Cutting Analysis System) apparatus, and the results are shown in Figure 4 below.

[0125] Specifically, the interfacial adhesion force was measured using a SAICAS system (SAICASEN-EX (Daipla Wintes, Japan)). The horizontal force was measured through the force applied to the blade while the positive electrode was being cut in the depth direction with a diamond microblade. The horizontal force is the value of the force applied to the microblade in the horizontal direction to maintain the constant cutting speed.

[0126] In the composite positive electrodes according to Example 1 and Comparative Example 8, the internal adhesive force between the composite positive electrode materials was measured in constant velocity mode, and the interfacial adhesive force between the composite positive electrode and the current collector was measured in constant load mode (Rake angle: 20°, Clearance angle: 10°). Figures 4(a) and 4(b) show the internal adhesive force between the composite positive electrode materials, and Figures 4(c) and 4(d) show the interfacial adhesive force between the composite positive electrode and the current collector.

[0127] The greater the horizontal force required to maintain the set cutting speed, the harder the material is, making it difficult to cut, and thus indicating superior adhesive strength. This revealed that the composite cathode of Example 1 has superior adhesive strength at the interface and internally compared to the composite cathode of Comparative Example 8.

[0128] Experimental Example 7: Mechanical property evaluation of composite cathodes using EMG ternary copolymer binder (Nano scratch) - Hardness measurement The hardness of the composite cathodes produced in Example 1 and Comparative Example 8 was measured. The evaluation was performed using a nano-scratch device, and the results are shown in Figure 5 below.

[0129] Specifically, the hardness was measured using a nanoscratch device (manufactured by Anton Paar). Following a preliminary procedure, a blade embedded in the electrode was moved at a constant velocity horizontally and vertically while maintaining the same load, covering a distance of approximately 50 μm within the electrode. The penetration depth of the blade within the positive electrode was then measured (Scanning velocity = 10 μm / s, Scratch load = 200 mN). Figure 5(a) is a schematic diagram of the nanoscratch device.

[0130] When the same load value is set, the penetration depth of the blade decreases as the material has superior hardness. We confirmed that the penetration depth was shallower with the composite cathode of Example 1 compared to the composite cathode of Comparative Example 8. Figure 5(b) shows the measurement results of the penetration depth. This confirmed that the composite cathode of Example 1 has superior hardness compared to the composite cathode of Comparative Example 8.

[0131] Experimental Example 8: Measurement of surface activity of composite cathode active material using EMG ternary copolymer binder The surface activation degree of the positive electrode active material distributed within the composite positive electrode in Example 1 and Comparative Example 8 was compared. The GITT (Galvanostatic Intermittent Titration Technique) analysis results are shown in Figure 6 below.

[0132] All-solid-state batteries according to Example 1 and Comparative Example 8 were prepared by charging and discharging at a current rate of 0.05C, and then a charged state was prepared at a current rate of 0.05C. Subsequently, a current of 0.2C was applied for 1 minute, followed by a 2-hour rest period, and the surface activation degree of the positive electrode active material was compared.

[0133] The all-solid-state battery according to Example 1 showed lower polarization than the all-solid-state battery according to Comparative Example 8. The final discharge capacity was 189.8 mAh / g for Example 1 and 181.0 mAh / g for Comparative Example 8, confirming that the surface activation degree of the positive electrode active material was superior in Example 1.

[0134] Experimental Example 9: Measurement of ionic conductivity of a composite solid electrolyte using an EMG ternary copolymer binder. The ionic conductivity of the composite solid electrolyte applied to the all-solid-state batteries of Example 1 and Comparative Example 8 was measured. A solid electrolyte sheet was manufactured by mixing LPSCl solid electrolyte and a binder in a weight ratio of 95:5. Figure 7(b) is a drawing showing the manufactured solid electrolyte sheet.

[0135] The ionic conductivity of LPSCl alone was 2.41 mS / cm, and in compositions with binders, similar values ​​were observed: 0.44 mS / cm when nitrile rubber was included and 0.45 mS / cm when EMG ternary copolymer was included. Figure 7(a) shows the ionic conductivity of the composite solid electrolyte applied to all-solid-state batteries according to Comparative Example 8 and Example 1. This confirms that the EMG ternary copolymer binder exhibits similar properties to the nitrile rubber binder in terms of ionic conductivity.

[0136] Experimental Example 10: Evaluation of cycle life characteristics of composite cathode-based all-solid-state batteries with varying EMG ternary copolymer binder content. Prior to evaluating the all-solid-state batteries manufactured in Examples 1 to 3, the optimal binder composition was explored by applying different amounts of EMG ternary copolymer.

[0137] Figure 8 shows the charge-discharge curve of a formation cycle obtained by charging and discharging at a current rate of 0.05C. Table 4 below shows the positive electrode active material-based discharge capacity of all-solid-state batteries containing 1, 2, and 3% by weight of EMG ternary copolymer binder.

[0138] [Table 4]

[0139] Figure 9 shows the discharge capacity obtained by performing two formation cycles and charging and discharging at a current rate of 0.2C. Table 5 below shows the initial discharge capacity and capacity retention rate after 20 cycles at a current rate of 0.2C.

[0140] [Table 5]

[0141] As shown in Table 5 above, the all-solid-state battery in Example 1, to which 2% by weight of EMG ternary copolymer binder was applied, exhibited the best cycle characteristics. Therefore, it can be concluded that the optimal content of EMG ternary copolymer binder is 2% by weight.

[0142] Experimental Example 11: Cycle life and high-efficiency performance evaluation of a composite cathode-based all-solid-state battery using an EMG ternary copolymer binder. Figure 10 shows the charge-discharge curves of the formation cycle obtained by charging and discharging the all-solid-state batteries manufactured in Comparative Example 8 and Example 1 at a current rate of 0.05C. The all-solid-state batteries of Comparative Example 8 and Example 1 showed the discharge capacity as shown in Table 6 below, based on the positive electrode active material.

[0143] [Table 6]

[0144] As shown in Table 6 above, the all-solid-state battery of Example 1 has a higher initial capacity than the all-solid-state battery of Comparative Example 8. Table 7 below shows the efficiency (discharge capacity / charge capacity × 100%) in the initial formation cycle.

[0145] [Table 7]

[0146] To verify the efficiency, CV (Cyclic Voltammetry) analysis was performed, and the results are shown in Figure 11. The nitrile rubber and EMG ternary copolymer electrolyte sheet used in the analysis is the solid electrolyte sheet with a 5 wt% binder weight ratio applied in Experimental Example 9. The voltage range was 1.0V to 3.7V (vs. Li-In), and the evaluation was performed at an injection rate of 0.5 mV / s. The observation of more side reactions during the initial voltage rise process in Comparative Example 8 explains the difference in efficiency in the initial formation cycle for battery life evaluation. The discharge capacity obtained by performing two formation cycles and charging and discharging at a current rate of 0.2C is shown in Figure 12. The initial discharge capacity and capacity retention rate of the all-solid-state batteries in Comparative Example 8 and Example 1 at a current rate of 0.2C are shown in Table 8 below.

[0147] [Table 8]

[0148] As shown in Table 8 above, the all-solid-state battery of Example 1, to which the EMG ternary copolymer binder was applied, exhibits superior cycle characteristics. Figure 13 shows the discharge capacity of the all-solid-state batteries produced in Comparative Example 8 and Example 1 as the current rate changes. The discharge capacity at a current rate of 1.0C is shown in Table 9 below.

[0149] [Table 9]

[0150] As shown in Table 9 above, the all-solid-state battery of Example 1 exhibits superior efficiency characteristics compared to Comparative Example 8.

[0151] Experimental Example 12: Cross-sectional image analysis of composite cathodes using EMG ternary copolymer binder To compare the cross-sectional views of composite cathodes for all-solid-state batteries before and after cycling, depending on the type of polymer binder applied, scanning electron microscopy (Field Emission Scanning Electron Microscopy, FE-SEM, Hitachi) analysis of the composite cathode cross-sections was performed, and the results are shown in Figure 14.

[0152] Figure 14(a) shows a cross-sectional image of the composite positive electrode for an all-solid-state battery manufactured from Comparative Example 8 before cycling, and Figure 14(b) shows a cross-sectional image of the composite positive electrode for an all-solid-state battery manufactured from Example 1 before cycling. In the cross-sectional images before cycling, it can be observed that there are no cracks in the positive electrode active material in both the case where the nitrile rubber binder of Comparative Example 8 was applied and the case where the EMG ternary copolymer binder of Example 1 was applied.

[0153] Figure 14(c) shows a cross-sectional image of the composite cathode for an all-solid-state battery manufactured from Comparative Example 8 after 100 cycles, and Figure 14(d) shows a cross-sectional image of the composite cathode for an all-solid-state battery manufactured from Example 1 after 100 cycles. After 100 cycle evaluation, numerous active material cracks were found in Comparative Example 8, whereas in Example 1, the morphology of the active material was generally well preserved, and it was confirmed that the interface between the active material and the solid electrolyte was stably maintained.

Claims

1. It comprises a positive electrode active material, a conductive material, a solid electrolyte, and a polymer binder. The polymer binder is a ternary copolymer polymer containing repeating units derived from ethylene, repeating units derived from methyl acrylate, and repeating units derived from glycidyl methacrylate. The polymer binder is a ternary copolymer polymer containing repeating units represented by the following chemical formula 1, repeating units represented by the following chemical formula 2, and repeating units represented by the following chemical formula 3. 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 In the aforementioned chemical formulas 1 to 3, p, q, and r are the number of moles in the repeating unit, respectively. p, q, and r are each independent integers between 1 and 100. The polymer binder is a composite cathode in which the molar ratio of p:q is 30 to 50:1 to 5 per mole of r.

2. The composite cathode according to claim 1, wherein the polymer binder is a polymer containing cross-repeating units represented by the following chemical formula 4: 【Chemistry 4】 In the aforementioned chemical formula 4, A is a repeating unit represented by the aforementioned chemical formula 1, B is a repeating unit represented by the aforementioned chemical formula 2, and C is a repeating unit represented by the aforementioned chemical formula 3.

3. The composite positive electrode according to claim 1, wherein p:q:r is 40:4:

1.

4. The composite cathode according to claim 1, wherein the content of the polymer binder is 3% by weight or less based on the total weight of the composite cathode.

5. The positive electrode active material includes a lithium transition metal composite oxide. The composite cathode according to claim 1, wherein the transition metal includes one or more of Co, Mn, Ni, and Al.

6. The lithium transition metal composite oxide comprises at least one of the compounds represented by the following chemical formula 5, according to claim 5: [Chemical formula 5] Li ｘ Ni ａ Co ｂ Mn ｃ M ｚ O ｙ In the aforementioned chemical formula 5, 0.5 ≤ x ≤ 1.5, 0 ≤ a ≤ 1, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ z < 1, 1.5 < y < 5, a + b + c + z is 1 or less, and M contains one or more elements selected from Al.

7. The composite cathode according to claim 1, wherein the solid electrolyte is a sulfide-based solid electrolyte.

8. The sulfide-based solid electrolyte is Li ６ PS ５ Cl, Li ６ PS ５ Br, Li ６ PS ５ I, Li ２ S-P ２ S ５ , Li ２ S-LiI-P ２ S ５ , Li ２ S-LiI-Li ２ O-P ２ S ５ , Li ２ S-LiBr-P ２ S ５ , Li ２ S-Li ２ O-P ２ S ５ , Li ２ S-Li ３ PO ４ -P ２ S ５ , Li ２ S-P ２ S ５ -P ２ S ５ , Li ２ S-P ２ S ５ -SiS ２ , Li ２ S-P ２ S ５ -SnS, Li ２ S-P ２ S ５ -Al ２ S ３ , Li ２ S-GeS ２ and Li ２ S-GeS ２ -ZnS, the composite positive electrode according to claim 7, which comprises at least one selected from the group consisting of the above.

9. A composite positive electrode according to any one of claims 1 to 8; Negative electrode; and An all-solid-state battery that includes a solid electrolyte interposed between them.

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