Positive electrode for all-solid-state battery and all-solid-state battery comprising same

Abstract

The present invention relates to a positive electrode for an all-solid-state battery and an all-solid-state battery comprising same, the positive electrode comprising: a current collector; and a positive electrode active material layer on the current collector, wherein the positive electrode active material layer further comprises a positive electrode active material, a solid electrolyte of chemical formula 1, and a binder, and the positive electrode active material has the effects of reducing the porosity of the positive electrode and improving ionic conductivity and electrical conductivity. [Chemical formula 1] LiaPbScCldXe. In chemical formula 1, 4≤a≤7, 0≤b≤1, 3≤c≤5, 0≤d<0.3, and d<e≤3, and X is Br or I.

Description

Cathode for all-solid-state battery and all-solid-state battery containing same

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0099100, dated July 26, 2024, the entire disclosure of which is incorporated herein by reference.

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

[0003]

[0004] Lithium secondary batteries are widely used as power sources for portable devices, including IT mobile devices. Recently, the market has been rapidly growing, shifting from small-sized lithium secondary batteries to medium- to large-sized ones. Their use as automotive batteries is particularly rapidly increasing. For lithium secondary batteries to be used as power sources for electric vehicles, high energy density and high output characteristics are required, and ensuring safety is particularly important.

[0005] Existing lithium secondary batteries use liquid, non-aqueous organic electrolytes, which pose a risk of ignition and explosion. Since explosions in products using these electrolytes continue to occur, addressing these issues is urgent.

[0006] All-solid-state batteries replace these organic electrolytes with solid electrolytes, and are batteries in which all battery components, including electrodes and electrolytes, are made of solid materials. Due to the high safety of the solid electrolyte itself, it is possible to fundamentally resolve the risk of fire and explosion.

[0007] Candidates for solid electrolytes in all-solid-state lithium-ion secondary batteries include gel-type polymer electrolytes, sulfide-based solid electrolytes, and oxide-based solid electrolytes. Among them, sulfide-based solid electrolytes are 1X10 -2It exhibits a high lithium ion conductivity value of more than S / cm and has a wide potential window of more than 5 V, so there is little deterioration of characteristics even in extreme environments, and it also has great advantages in the design of high-energy density lithium ion secondary batteries.

[0008] Since all-solid-state batteries utilize solid electrolytes, their cathode active material layer must include a solid electrolyte to ensure a lithium ion conduction path. Therefore, the cathode active material layer in an all-solid-state battery comprises a cathode active material, a binder, and a solid electrolyte. To reduce the porosity of the cathode of an all-solid-state battery, improve ionic and electrical conductivity, and enhance the energy density of the all-solid-state battery, the structure of the solid electrolyte contained in the cathode active material layer must be improved, and research into this area is urgently needed.

[0009]

[0010] [Previous literature]

[0011] [Patent Document]

[0012] Republic of Korea Patent No. 10-2228383

[0013]

[0014] The present invention aims to provide a positive electrode for an all-solid-state battery capable of reducing the porosity of the positive electrode and improving ionic conductivity and electrical conductivity.

[0015] In addition, the present invention aims to provide an all-solid-state battery having excellent energy density by including the positive electrode.

[0016]

[0017] To achieve the above purpose,

[0018] The present invention comprises: a collector; and

[0019] A positive electrode for an all-solid-state battery, comprising a positive electrode active material layer positioned on the above-mentioned collector;

[0020] The above positive electrode active material layer provides a positive electrode for an all-solid-state battery including a positive electrode active material, a solid electrolyte of the following chemical formula 1, and a binder.

[0021] [Chemical Formula 1]

[0022] Li a P b S c Cl d X e

[0023] In the above chemical formula 1,

[0024] 4≤a≤7, 0≤b≤1, 3≤z≤5, 0≤d<0.3 and d <e≤3이고,

[0025] X is Br or I.

[0026] In addition, the present invention provides an all-solid-state battery comprising the positive electrode of the present invention; a negative electrode; and a solid electrolyte layer positioned between the positive electrode and the negative electrode.

[0027]

[0028] The positive electrode for an all-solid-state battery of the present invention can reduce the porosity of the positive electrode and improve the ionic conductivity and electrical conductivity of the positive electrode by including a solid electrolyte containing an excess amount of bromine or iodine.

[0029] In addition, an all-solid-state battery including the positive electrode of the present invention can have an excellent energy density effect.

[0030]

[0031] Figure 1 shows the results of measuring the porosity of the anode of Experimental Example 1.

[0032] Figure 2 shows the results of measuring the discharge capacity of the positive electrode of Experimental Example 3.

[0033] Figure 3 shows the results of measuring the life characteristics of the anode of Experimental Example 3.

[0034]

[0035] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0036] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. It should be understood that the terms "comprise" or "have" in the present invention are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0037]

[0038] Hereinafter, the present invention will be described in more detail.

[0039]

[0040] All-solid-state batteries utilize a solid electrolyte instead of a liquid electrolyte. To ensure a conductive path for lithium ions, the positive electrode active material layer includes a solid electrolyte. The present invention aims to provide an all-solid-state battery positive electrode with reduced porosity and enhanced ionic and electrical conductivity by improving the solid electrolyte contained in the positive electrode active material layer.

[0041]

[0042] Cathode for all-solid-state batteries

[0043] The present invention relates to a positive electrode for an all-solid-state battery, comprising: a current collector; and a positive electrode active material layer positioned on the current collector; wherein the positive electrode active material layer may include a positive electrode active material, a solid electrolyte of the following chemical formula 1, and a binder.

[0044] [Chemical Formula 1]

[0045] Li a P b S c Cl d X e

[0046] In the above chemical formula 1,

[0047] 4≤a≤7, 0≤b≤1, 3≤z≤5, 0≤d<0.3 and d <e≤3이고,

[0048] X is Br or I.

[0049] Therefore, the solid electrolyte of the above chemical formula 1 is Li a P b S c Cl d Br e or Li a P b S c Cl d I e It could be.

[0050] In the above chemical formula 1, d is 0≤d<0.3, preferably 0 <d<0.3일 수 있다.

[0051] Also, in the above chemical formula 1, e is d <e≤3이며, e≥7d일 수 있다. 상기 e≥7d일 경우 d는 0이 아니다. 상기 화학식 1에서 d<e≤3 및 e≥7d임에 따라 상기 화학식 1에서 X는 과량으로 포함되는 것일 수 있다. 상기 화학식 1에서 X가 과량으로 포함됨에 따라 상기 화학식 1의 고체 전해질과 양극 활물질의 접촉 면적이 증가하여 양극의 이온 전도도 및 전기 전도도 개선 효과를 얻을 수 있으며, 그에 따라 상기 양극을 포함하는 전고체 전지는 향상된 에너지 밀도를 얻을 수 있다.

[0052] Therefore, it is possible to secure low porosity of the positive electrode for an all-solid-state battery, and improve ionic conductivity and electrical conductivity. If e is e≤d or e<7d, X is not included in excess, and thus the above effect cannot be obtained. In addition, e may preferably be 0.5≤e≤3, and most preferably 0.5≤e≤1.5.

[0053] The solid electrolyte of the above chemical formula 1 may be included in an amount of 3 to 30 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the solid electrolyte of the above chemical formula 1 may be 3 wt% or more, 5 wt% or more, 7 wt% or more, or 10 wt% or more, and may be 30 wt% or less, 25 wt% or less, 20 wt% or less, or 10 wt% or less. If the content of the solid electrolyte of the above chemical formula 1 is less than 3 wt%, the effect of improving the ionic conductivity and electrical conductivity of the positive electrode may be minimal, and if it exceeds 30 wt%, the content of the positive electrode active material and binder may relatively decrease, resulting in deterioration in battery performance.

[0054]

[0055] The above positive electrode active material may vary depending on the type of all-solid-state battery. For example, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4(0≤x≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site lithium nickel oxide represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01≤x≤0.3); chemical formula LiMn 2-x M xLithium manganese composite oxides expressed as O2 (M = Co, Ni, Fe, Cr, Zn or Ta; 0.01≤x≤0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn); LiNi x Mn 2-x Lithium manganese composite oxide with spinel structure represented by O4; LiCoPO4; LiFePO4; Elemental sulfur (S8); Li2S n (n≥1), organosulfur compounds or carbon-sulfur polymers (C2S x ) n : It may include sulfur series compounds such as x=2.5 ~ 50, n=2), but is not limited to these.

[0056] The positive electrode active material may be included in an amount of 65 to 95 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 65 wt% or more, 70 wt% or more, 75 wt% or more, or 80 wt% or more. It may be 95 wt% or less, 90 wt% or less, or 85 wt% or less. If the content of the positive electrode active material is less than 65 wt%, battery performance may deteriorate, and if it exceeds 95 wt%, mass transfer resistance may increase.

[0057]

[0058] The above binder enhances the bonding strength between the components constituting the positive electrode active material layer and between them and the current collector, and any binder known in the industry can be used.

[0059] For example, the binder may be a fluororesin binder including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); a rubber binder including styrene butadiene rubber (SBR), acrylonitrile-butidiene rubber, and styrene-isoprene rubber; a cellulose binder including carboxyl methyl cellulose (CMC), starch, hydroxy propyl cellulose, and regenerated cellulose; a polyalcohol binder; a polyolefin binder including polyethylene and polypropylene; a polyimide binder; a polyester binder; and a silane binder. One, two or more mixtures or copolymers selected from the group consisting of may be used.

[0060] In addition, the binder may be included in an amount of 0.1 to 5 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the binder may be 0.1 wt% or more, 0.5 wt% or more, or 0.8 wt% or more, and may be 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, or 1.5 wt% or less. If the content of the binder is less than 0.1 wt%, the effect of improving the bonding strength between materials included in the positive electrode active material layer may be minimal, and thus the electrode sheet may not be properly formed. If the content of the binder is more than 5 wt%, the ionic conductivity or electrical conductivity of the positive electrode may be reduced.

[0061]

[0062] The above-described positive electrode active material layer may additionally include a conductive material. The conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, has excellent electrical conductivity without causing chemical changes in the battery, and so on.

[0063] For example, the conductive material may include graphite or conductive carbon, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, and summer black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; metal powders such as aluminum powder or nickel powder; conductive whiskeys such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in combination of two or more, but are not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0064] The conductive material may be included in an amount of more than 0 wt% and less than 5 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the conductive material may be 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 1.5 wt% or more, or 2 wt% or more, and may be 5 wt% or less, 4 wt% or less, or 3 wt% or less. If the conductive material is not included, it is difficult to expect an effect of improving electrical conductivity or the electrochemical characteristics of the battery may deteriorate, and if it exceeds 5 wt% and is too much, the amount of the positive electrode active material may be relatively small, which may result in a decrease in capacity and energy density.

[0065]

[0066] In one embodiment of the present invention, the positive electrode active material layer is formed by applying a composition for forming a positive electrode active material layer, which comprises a positive electrode active material, a solid electrolyte of the above chemical formula 1, and a binder, onto a current collector, and the composition may not contain a solvent. Accordingly, the positive electrode for an all-solid-state battery of the present invention may be a dry positive electrode.

[0067] In another embodiment of the present invention, the positive electrode active material layer is formed by applying and drying a composition for forming a positive electrode active material layer, which includes a positive electrode active material, a solid electrolyte of the chemical formula 1, a binder, and a solvent, onto a current collector, and the positive electrode for an all-solid-state battery of the present invention may be a wet positive electrode.

[0068]

[0069] The above positive electrode current collector is intended to support the positive electrode active material layer, and is not particularly limited as long as it has excellent conductivity and is electrochemically stable in the voltage range of the lithium secondary battery. For example, the positive electrode current collector may be any one metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be surface-treated with carbon, nickel, titanium, or silver. As the alloy, an aluminum-cadmium alloy may be preferably used. In addition, calcined carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer may be used.

[0070] The above positive electrode current collector can form fine irregularities on its surface to strengthen the bonding strength with the positive electrode active material, and can be used in various forms such as a film, sheet, foil, mesh, net, porous body, foam, and non-woven fabric.

[0071]

[0072] The porosity of the positive electrode may be 0.1 to 40%. As described above, since the positive electrode active material layer includes the solid electrolyte of the chemical formula 1, the contact area between the positive electrode active material and the solid electrolyte of the chemical formula 1 increases, thereby allowing the positive electrode to have the porosity described above. Therefore, the positive electrode of the present invention may have an ion conduction path effectively formed.

[0073] In addition, the ionic conductivity of the above anode is 1X10 at 60℃. -6 Inside 1X10 -3mS / cm, and the electrical conductivity is 1X10 -6 Inside 1X10 -3 It may be mS / cm. As described above, since the positive electrode active material layer includes the solid electrolyte of the chemical formula 1, the contact area between the positive electrode active material and the solid electrolyte may increase. Accordingly, the positive electrode of the present invention may have excellent ionic conductivity and electrical conductivity as described above.

[0074]

[0075] All-solid-state batteries

[0076] The present invention relates to an all-solid-state battery comprising: a positive electrode; a negative electrode; and a solid electrolyte layer between the positive electrode and the negative electrode; wherein the positive electrode is the positive electrode of the present invention described above.

[0077] The above-mentioned negative electrode may include a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector. In addition, the negative electrode, like the positive electrode, may include a conductive material and a binder as needed. In this case, the negative electrode current collector, conductive material, and binder are as described above.

[0078] The above negative active material is lithium ion (Li + ) can be reversibly intercalated or deintercalated, or any material that can react with lithium ions to form a reversibly lithium-containing compound.

[0079] For example, the negative active material may be at least one carbon-based material selected from the group consisting of crystalline artificial graphite, crystalline natural graphite, amorphous hard carbon, low-crystalline soft carbon, carbon black, acetylene black, Ketjen black, Super-P, graphene, and fibrous carbon, Si-based material, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me´ y Oz (Me: Mn, Fe, Pb, Ge; Me´: Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물; 리튬 티타늄 산화물 등을 포함할 수 있지만, 이들만으로 한정되는 것은 아니다.

[0080] Additionally, the negative electrode may include a negative electrode current collector and a coating layer including metal-carbon composite particles positioned on the negative electrode current collector. This may mean an anodeless electrode that does not include a negative electrode active material.

[0081] The above negative electrode may be such that when the all-solid-state battery is charged, lithium ions pass through the coating layer to reach the surface of the negative electrode current collector, and these are deposited to form a lithium metal layer.

[0082] The above metal-carbon composite particles may have a form in which carbon particles and metal particles are attached to each other or one surface is coated with the other, and may be physically or chemically bonded.

[0083] The above carbon particles may include natural graphite, artificial graphite, hard carbon, soft carbon, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon nanotubes, fullerene, carbon fiber, and fluorocarbon.

[0084] The above metal particles are lithium-philic metals, for example, Ni, Cu, Ag, Au, Pt, Al, Zn, Bi, etc., and may be one or a combination of two or more thereof. By introducing a metal having the above lithium-philic properties, it is advantageous to form a stable and uniform lithium layer on the surface of the current collector.

[0085] The above negative electrode may be manufactured by mixing a binder solution and the composite particles to prepare a slurry for forming a coating layer, and then applying and drying the slurry on a negative electrode current collector. In this case, the binder may be a conventional binder used in the art.

[0086] The above solid electrolyte layer is formed of a solid electrolyte in a layered form, and the solid electrolyte may be the solid electrolyte of the above chemical formula 1, or a solid electrolyte different from the above chemical formula 1. The solid electrolyte different from the above chemical formula 1 may include at least one selected from the group consisting of a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte, and preferably may include a sulfide-based solid electrolyte.

[0087] The above sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramic.

[0088] Specifically, the sulfide-based solid electrolyte may include at least one 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, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, and preferably may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The above Li6PS5Cl, Li6PS5Br, and Li6PS5I may be argyrodite type solid electrolytes. In addition, the sulfide-based solid electrolyte may be in a form doped with trace elements, for example, Li6PS5Cl may be additionally doped with bromine (Br).

[0089] The above polymer-based solid electrolyte is a polymer electrolyte material formed by adding a polymer resin to a composite of a lithium salt and a polymer resin, that is, a solvated lithium salt, and is about 1x10 -7 S / cm or more, preferably about 1x10 -5 It can exhibit ionic conductivity of S / cm or more.

[0090] Non-limiting examples of the polymer resin include polyether polymers, polycarbonate polymers, acrylate polymers, polysiloxane polymers, phosphazene polymers, polyethylene derivatives, alkylene oxide derivatives such as polyethylene oxide, phosphate ester polymers, polyagitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc., and may include one or more of these. In addition, the polymer electrolyte may include, as a polymer resin, a branched copolymer in which an amorphous polymer such as PMMA, polycarbonate, polysiloxane (PDMS) and / or phosphazene is copolymerized as a comonomer in a polyethylene oxide (PEO) main chain, a comb-like polymer, and a cross-linked polymer resin, and may include one or more of these.

[0091] In the above polymer solid electrolyte, the above-mentioned lithium salt is an ionizable lithium salt, Li + X - It can be expressed as . There is no particular limitation on the anion of these lithium salts, but F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH- , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , (CF3CF2SO2)2N - Examples include:

[0092] The above oxide-based solid electrolyte may contain oxygen (O) and have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, an LLTO-based compound, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP compounds, LATP compounds, Li1 +x Ti 2-x Al x Si y (PO4) 3-y (where, 0≤x≤1, 0≤y≤1), LiAl x Zr 2-x (PO4)3(where 0≤x≤1, 0≤y≤1), LiTi x Zr 2-x (PO4)3 (wherein, 0≤x≤1, 0≤y≤1), may include at least one selected from among LISICON compounds, LIPON compounds, perovskite compounds, NASICON compounds, and LLZO compounds.

[0093]

[0094] The positive electrode active material layer of the positive electrode for the all-solid-state battery of the present invention includes a solid electrolyte of the above chemical formula 1. The solid electrolyte of the above chemical formula 1 satisfies 0≤d<0.3, d <e≤3 및 e≥7d인 것으로 Cl은 미량으로 포함되고, X(Br 또는 I)가 과량으로 포함된 것이다. 따라서, 상기 화학식 1의 고체 전해질과 양극 활물질의 접촉 면적이 증가하여 양극의 기공도를 감소시키고, 이온 전도 경로(path)가 효과적으로 형성되어 양극의 이온 전도도 및 전기 전도도를 향상시킬 수 있다. 그에 따라, 상기 양극을 포함하는 전고체 전지는 개선된 에너지 밀도를 얻을 수 있다.

[0095]

[0096] Hereinafter, the present invention will be described in more detail through examples, but the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited to these examples.

[0097]

[0098] <Manufacturing of anodes for all-solid-state batteries>

[0099] Example 1.

[0100] Cathode active material (NCM 811), conductive material (carbon fiber), solid electrolyte (Li6PS5Cl) 0.1 Br 0.9 ) and a binder (polytetrafluoroethylene) were prepared. The composition for forming a positive electrode active material layer was applied to a positive electrode current collector to prepare a positive electrode in which a positive electrode active material layer was formed on the current collector.

[0101]

[0102] Comparative Example 1.

[0103] A positive electrode was manufactured in the same manner as in Example 1, except that Li6PS5Cl was used as the solid electrolyte.

[0104]

[0105] Comparative Example 2.

[0106] Li6PS5Cl as a solid electrolyte0.5 Br 0.5 The positive electrode was manufactured in the same manner as in Example 1 except that .

[0107]

[0108] Experimental Example 1. Measurement of porosity of anode for all-solid-state batteries

[0109] The porosity of the positive electrodes for all-solid-state batteries manufactured in Example 1, Comparative Example 1 and Comparative Example 2 was measured. The porosity was measured by dividing each positive electrode into 2X2cm 2 After being struck, the weight and thickness were measured, and the results are shown in Figure 1.

[0110] In the above porosity measurement results, the porosity of Example 1 was measured as 12.1%, while the porosity of Comparative Example 1 was measured as 14.3% and the porosity of Comparative Example 2 was measured as 15.1%. That is, the porosity of the all-solid-state battery positive electrode of Example 1 was lower than the porosities of the all-solid-state battery positive electrodes of Comparative Examples 1 and 2.

[0111] The solid electrolyte of the positive electrode active material layer of Comparative Example 1 does not include X, and Comparative Example 2 has d of 0.5 and e of 0.5, so the positive electrode active material layers of Comparative Examples 1 and 2 do not include the solid electrolyte of Chemical Formula 1. Accordingly, the contact between the positive electrode active material and the solid electrolyte did not increase, so the positive electrodes for all-solid-state batteries of Comparative Examples 1 and 2 showed higher porosity than the positive electrode for all-solid-state batteries of Example 1. On the other hand, the positive electrode active material layer of Example 1 showed low porosity because it included the solid electrolyte of Chemical Formula 1, so the contact between the positive electrode active material and the solid electrolyte increased.

[0112]

[0113] Experimental Example 2. Measurement of ionic and electrical conductivity of a cathode for an all-solid-state battery.

[0114] The ionic conductivity and electrical conductivity of the positive electrodes for all-solid-state batteries manufactured in Example 1, Comparative Example 1, and Comparative Example 2 were measured. The ionic conductivity and electrical conductivity were measured by Electrochemical Impedance Spectroscopy (60°C, 0.01-10 6 Hz) and the results are shown in Table 1 below.

[0115]

[0116] Example 1 Comparative Example 1 Comparative Example 2 Electrical Conductivity (mS / cm) 3.0 X10 -4 2.7X10 -4 1.6X10 -4 Ionic conductivity (mS / cm) 1.7 X10 -4 1.4 X10 -4 4.8X10 -5

[0117]

[0118] In the results of Table 1 above, the electrical conductivity and ionic conductivity of the all-solid-state battery positive electrode of Example 1 were superior to those of the all-solid-state battery positive electrodes of Comparative Examples 1 and 2. As described above in Experimental Example 1, the positive electrode active material layer of Comparative Examples 1 and 2 did not include the solid electrolyte of Chemical Formula 1. Accordingly, the contact between the positive electrode active material and the solid electrolyte did not increase, and thus the all-solid-state battery positive electrodes of Comparative Examples 1 and 2 showed lower electrical conductivity and ionic conductivity than those of the all-solid-state battery positive electrode of Example 1.

[0119] Since the positive electrode active material layer of Example 1 includes the solid electrolyte of the above chemical formula 1, the contact between the positive electrode active material and the solid electrolyte increases, resulting in excellent electrical conductivity and ionic conductivity.

[0120]

[0121] Experimental Example 3. Measurement of discharge capacity and cycle life characteristics of a cathode for an all-solid-state battery.

[0122] The discharge capacity and life characteristics of the positive electrodes for all-solid-state batteries manufactured in Example 1, Comparative Example 1, and Comparative Example 2 were measured.

[0123] Discharge capacity and life characteristics were measured by charging the positive electrode for an all-solid-state battery at 0.33C in CCCV mode at a temperature of 60℃ to 4.25 V, and then discharging to 3.0 V with a constant current for 50 charge and discharge cycles, and measuring the capacity retention rate. The discharge capacity results are shown in Fig. 2, and the life characteristics results are shown in Fig. 3.

[0124] As described above in Experimental Example 1, the positive electrode active material layers of Comparative Examples 1 and 2 do not include the solid electrolyte of Chemical Formula 1. Accordingly, in the results of Experimental Examples 1 and 2, the positive electrodes for all-solid-state batteries of Comparative Examples 1 and 2 showed high porosity and low electrical conductivity and ionic conductivity, whereas the positive electrode active material layer for all-solid-state batteries of Example 1 included the solid electrolyte of Chemical Formula 1, and therefore, in the results of Experimental Examples 1 and 2, the positive electrodes showed low porosity and excellent electrical conductivity and ionic conductivity.

[0125] Therefore, the all-solid-state battery positive electrode of Example 1, which had low porosity and high electrical and ionic conductivities, showed excellent discharge capacity and lifespan characteristics. However, the all-solid-state battery positive electrodes of Comparative Examples 1 and 2, which had high porosity and low electrical and ionic conductivities, showed lower discharge capacity and lifespan characteristics than Example 1.

[0126] From this, it was found that when the positive electrode active material layer includes the solid electrolyte of the above chemical formula 1, the contact between the positive electrode active material and the solid electrolyte of the above chemical formula 1 increases, thereby reducing the porosity of the positive electrode and improving ionic conductivity and electrical conductivity. In addition, it was found that the energy density of the positive electrode and the all-solid-state battery including the positive electrode can be improved due to the above effect.

Claims

1. The entire house; and A positive electrode for an all-solid-state battery, comprising a positive electrode active material layer positioned on the above-mentioned collector; The above positive electrode active material layer is an all-solid-state battery positive electrode including a positive electrode active material, a solid electrolyte of the following chemical formula 1, and a binder: [Chemical Formula 1] Li a P b S c Cl d X e In the above chemical formula 1, 4≤a≤7, 0≤b≤1, 3≤z≤5, 0≤d<0.3 and d <e≤3이고, X is Br or I.

2. In paragraph 1, 0 in the above chemical formula 1 <d<0.3인, 전고체 전지용 양극.

3. In paragraph 2, A positive electrode for an all-solid-state battery, wherein e≥7d in the above chemical formula 1.

4. In paragraph 1, A positive electrode for an all-solid-state battery, wherein 0.5≤e≤3 in the above chemical formula 1.

5. In paragraph 1, An all-solid-state battery positive electrode, wherein the positive electrode active material layer comprises 65 to 95 wt% of the positive electrode active material, 3 to 30 wt% of the solid electrolyte of the chemical formula 1, and 0.1 to 5 wt% of the binder based on the total weight of the positive electrode active material layer.

6. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the positive electrode active material layer additionally includes a conductive material.

7. In paragraph 6, A positive electrode for an all-solid-state battery, wherein the above-mentioned conductive material is included in an amount of more than 0% by weight and less than or equal to 5% by weight based on the total weight of the positive electrode active material layer.

8. An all-solid-state battery comprising: a positive electrode according to any one of claims 1 to 7; a negative electrode; and a solid electrolyte layer positioned between the positive electrode and the negative electrode.

9. In paragraph 8, An all-solid-state battery, wherein the solid electrolyte of the above solid electrolyte layer includes a sulfide-based solid electrolyte.

10. In paragraph 9, An all-solid-state battery, wherein the solid electrolyte is the same as or different from the solid electrolyte of the chemical formula 1.

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