Positive electrode active material composite and manufacturing method therefor

Abstract

The present invention relates to a positive electrode active material composite comprising a positive electrode active material and a coating layer formed on the surface of the positive electrode active material, wherein the coating layer comprises a conductive material and a sulfide-based solid electrolyte containing the element Br.

Description

Anode active material composite and method for manufacturing the same

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0143404 filed on October 18, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0002] The present invention relates to a positive electrode active material composite comprising a positive electrode active material; and a coating layer formed on the surface of the positive electrode active material, wherein the coating layer comprises a conductive material and a sulfide-based solid electrolyte comprising Br element.

[0003] With the increasing technological development and demand for electronic devices, society's overall dependence on electrical energy is growing, leading to a rapid increase in the demand for secondary batteries capable of efficiently storing and utilizing electrical energy. Accordingly, there is a need for technological development in secondary batteries that offer improved safety alongside enhanced lifespan and charging capacity.

[0004] In the case of conventionally used secondary batteries, liquid electrolytes are generally used as described in Korean Registered Patent No. 10-2176091; however, safety issues such as short circuits occurring as the charging and discharging of the secondary battery are repeated have emerged, and consequently, secondary battery technology utilizing solid electrolytes is currently being developed.

[0005] However, when using a solid electrolyte in a secondary battery, unlike a liquid electrolyte which is injected into the voids of the electrode to form an ion conduction path, the ion conduction path is formed by physical interfacial contact; therefore, there is a technical challenge to prevent increased resistance and performance degradation caused by interfacial degradation during charge and discharge behavior.

[0006] Accordingly, there is a high need to develop active material composites that maintain uniform and close interfacial contact between the electrode active material and the solid electrolyte.

[0007] In order to solve the above-mentioned problems, the present invention introduces a coating layer containing a conductive material and a sulfide-based solid electrolyte containing Br element into the positive electrode active material particles to promote close interfacial contact between the positive electrode and the electrolyte layer (i.e., close interfacial contact between the positive electrode active material and the solid electrolyte).

[0008] Accordingly, the invention aims to improve the electronic conductivity, ionic conductivity, and / or Coulomb efficiency of the anode by using an anode active material composite comprising the anode active material to which the above coating layer is applied, and furthermore, to provide a secondary battery with improved energy density and improved charge / discharge capacity and lifespan characteristics by using the above anode.

[0009] The present invention relates to an anode active material composite comprising: an anode active material; and a coating layer formed on the surface of the anode active material; wherein the coating layer comprises a conductive material and a sulfide-based solid electrolyte containing Br element.

[0010] In one embodiment, the sulfide-based solid electrolyte containing the Br element may include an azirodite-based solid electrolyte containing the Br element.

[0011] In one embodiment, the sulfide-based solid electrolyte containing the Br element may include a compound of the following chemical formula 1.

[0012] [Chemical Formula 1]

[0013] Li a PS b X c Br d

[0014] In the above chemical formula 1, X is at least one selected from F, Cl, and I, and 5≤a≤6, 4≤b≤5, 0 <c≤1, 0<d≤1 이다.

[0015] In one embodiment, the content of the sulfide-based solid electrolyte containing the Br element may be 0.1 weight% or more to 5 weight% or less relative to the positive electrode active material.

[0016] In one embodiment, the conductive material may include a carbon-based conductive material.

[0017] In one embodiment, the carbon-based conductive material may comprise one or more selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber.

[0018] In one embodiment, the conductive material content may be 0.01 weight% or more to 1 weight% or less relative to the positive active material.

[0019] In one embodiment, the thickness of the coating layer may be 1 nm or more to 300 nm or less.

[0020] In one embodiment, the coating layer may be formed on an area corresponding to 10% or more to 99% or less of the surface of the positive active material.

[0021] The present invention relates to a positive electrode comprising the above-mentioned positive electrode active material complex.

[0022] In one embodiment, the porosity of the anode is 5% or more to 34% or less.

[0023] The present invention relates to a secondary battery comprising the above-mentioned positive electrode.

[0024] The present invention relates to a method for manufacturing an anode active material composite comprising: a step of preparing a composition for forming an anode active material composite by mixing an anode active material, a conductive material, and a sulfide-based solid electrolyte containing Br element; and a step of forming a coating layer on the surface of the anode active material by mixing the composition for forming the anode active material composite at a speed greater than 3400 rpm and less than 3800 rpm.

[0025] The positive electrode active material composite of the present invention has a coating layer uniformly formed on the positive electrode active material that includes a conductive material and a sulfide-based solid electrolyte containing Br element, thereby enabling the maintenance of close interfacial contact between the positive electrode active material and the solid electrolyte.

[0026] Thus, it was confirmed that a cathode with improved energy density can be manufactured by using the above-mentioned cathode active material composite, and that the manufactured cathode has improved electronic conductivity, ionic conductivity, charge / discharge capacity, high-rate characteristics, and / or lifespan characteristics.

[0027] Figure 1 is an SEM image of the cathode active material composite of Example 1. Figures 1(a) and 1(b) are SEM images taken at different magnifications, respectively.

[0028] Figure 2 is an SEM image of the surface of each cathode active material composite prepared by varying the final mixing speed in the mechanofusion method according to Experimental Example 2. Figure 2(a) is an SEM image of the surface of the cathode active material particles before coating. Figures 2(b) to 2(f) are SEM images of the surface of the cathode active material composite prepared when the final mixing speed was adjusted to 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, and 3800 rpm, respectively.

[0029] Figures 3(a) to 3(c) show the results of EDS analysis performed on Ni, S, and C, respectively, for the cathode active material composite of Example 1.

[0030] Figure 4 shows the results of measuring the porosity before and after WIP for anodes prepared using Example 1 and Comparative Example 2, respectively.

[0031] Figure 5 is a Nyquist plot showing the results of performing EIS on the anodes prepared using Example 1 and Comparative Example 1, respectively. The results of performing EIS analysis three times for each of the anodes are shown.

[0032] FIG. 6 shows the first cycle (1) for the all-solid-state battery prepared in Experimental Example 4. st This represents the charge / discharge capacity of the cycle.

[0033] Figure 7 shows the results of evaluating the capacity retention rate by C-rate for the all-solid-state battery manufactured in Experimental Example 4.

[0034] Figure 8 shows the retention rate relative to the initial capacity according to the number of charge-discharge cycles for the all-solid-state battery prepared in Experimental Example 4.

[0035] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0036] Therefore, the configurations of the embodiments described in this specification are merely one of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application. In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0037] In this specification, when a part is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Thus, for example, a composition comprising compound A may include compounds other than A. However, the term “comprising” also encompasses, in a more restrictive sense as a specific embodiment thereof, “essentially / essentially composed of” and “composed of,” so, for example, a “composition comprising compound A” may also be (essentially / essentially) composed of compound A.

[0038] In connection with this, terms such as “comprising” or “having,” as described in this specification, are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0039] In this specification, when any layer is described as being located “on” or “between” another arbitrary layer, this includes not only cases where any layer is in contact with another arbitrary layer, but also cases where another layer or material, etc., exists between the two layers.

[0040] Where in this specification a quantity, concentration, or other value or parameter is given as an enumeration of a range, a preferred range, a preferred upper limit, and a preferred lower limit, it should be understood that any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the range is disclosed separately, specifically discloses all ranges that may be formed. Where a range of numerical values ​​is mentioned in this specification, unless otherwise stated, for example, without limiting terms such as greater than or less than, the range is intended to include its endpoint value and all integers and fractions within that range. The scope of the invention is not intended to be limited to the specific value mentioned when defining the range.

[0041] Among the physical properties mentioned in this specification, if the measured temperature affects the property, the property is measured at room temperature unless specifically otherwise specified. The term "room temperature" refers to a natural temperature that has not been heated or cooled, and may mean, for example, any temperature within the range of about 10°C or higher to 30°C or lower, or about 23°C or about 25°C. Furthermore, unless specifically otherwise specified, the unit of temperature in this specification is °C.

[0042] In addition, among the physical properties mentioned in this specification, if the measured pressure affects the physical property, unless otherwise specifically defined, the physical property is measured at normal pressure, that is, atmospheric pressure (about 1 atmosphere).

[0043] One aspect of the present invention provides an anode active material composite comprising: an anode active material; and a coating layer formed on the surface of the anode active material, wherein the coating layer comprises a conductive material and a sulfide-based solid electrolyte comprising a Br element.

[0044] Another aspect of the present invention provides an anode active material composite comprising: an anode active material; and a coating layer formed on the surface of the anode active material; wherein the coating layer comprises a first conductive material and a first solid electrolyte comprising a Br element.

[0045] The above-mentioned positive active material may be a positive active material commonly used in lithium secondary batteries. Specifically, the above-mentioned positive active material may be a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a material with the chemical formula Li (1-b) (Ni x M 1 (1-x) )M 2 y O2(here M 1 is at least one selected from Co and Mn, and M 2 is at least one selected from Al, Zr, B, W, Mo, Cr, Ta, Nb, Mg, Ce, Hf, La, Ti, Sr, Ba, F, P, S, Na, Si, and Y, and 0 <b<0.1, 0.3≤x≤1, 0≤y≤0.1)의 층상구조 화합물; LiFe3O4등의 리튬 철 산화물; 화학식 Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3A lithium manganese complex oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, satisfying 0.01 ≤ c3 ≤ 0.1) or Li2Mn3MO8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); LiMn2O4 in which part of the Li of the chemical formula is substituted with an alkaline earth metal ion; an exemplarily lithium iron phosphate compound (LFP) having the chemical formula LiFePO4; LiFe x M1 (1-x) P y M2 (1-y) O4(wherein, M1 = 1 or more of Mn, Co, Ni, Al, V, B, Cd, Cu, Mg, Zn, Ti, Nb, Zr and Cr, and 0 <x≤1, M2 = Si, N, S, Cl, Br, 및 F 중 1 이상이며, 0<y≤1)의 화학식을 갖는 리튬 철 금속 인산화물(LMFP); 등을 들 수 있지만, 이들만으로 한정되는 것은 아니다. 상기 양극은 Li-metal일 수도 있다.

[0046] Average particle size (D of the above positive active material) 50 ) may be 2 μm or more to 10 μm or less, specifically 6 μm or more to 8 μm or less, but is not limited thereto.

[0047] The above "average particle size (D 50"" refers to the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size, and the said particle size may be measured using the laser diffraction method. Specifically, the powder to be measured is dispersed in a solvent or the powder in a dry state is introduced into the measurement unit under vacuum, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500). The particle size distribution is calculated by measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam. By calculating the particle diameter at the point where the cumulative distribution of particle numbers according to particle size in the measuring device reaches 50%, D 50 Particle size can be measured.

[0048] The content of the above-mentioned positive active material may be included in the positive active material composite in an amount of 50% by weight or more to 95% by weight or less, preferably 70% by weight or more to 90% by weight or less, based on the total weight of the positive active material composite, but is not limited thereto.

[0049] The coating layer is located on the surface of the positive electrode active material and may include a solid electrolyte and a conductive material. For example, the coating layer is located on the surface of the positive electrode active material and may include a sulfide-based solid electrolyte containing Br element and a conductive material.

[0050] For example, the coating layer may include a first solid electrolyte containing the element Br and a first conductive material.

[0051] The sulfide-based solid electrolyte containing the above-mentioned Br element may essentially contain the Br element. The sulfide-based solid electrolyte containing the above-mentioned Br element may additionally contain other doping elements other than the Br element.

[0052] The sulfide-based solid electrolyte containing the Br element may include an azirodite-based solid electrolyte containing the Br element. Specifically, the sulfide-based solid electrolyte containing the Br element may include a compound of the following chemical formula 1.

[0053] [Chemical Formula 1]

[0054] Li a PS b X c Br d

[0055] In the above chemical formula 1, X is at least one selected from F, Cl, and I, and 5≤a≤6, 4≤b≤5, 0 <c≤1, 0<d≤1 이다.

[0056] The sulfide-based solid electrolyte containing the Br element may include an azirodite-based sulfide-based solid electrolyte containing the Br element, and may additionally include other halogen elements other than the Br element. For example, the sulfide-based solid electrolyte containing the Br element may include the Br element and the Cl element.

[0057] When the coating layer includes the solid electrolyte, close interfacial contact between the positive electrode active material and the solid electrolyte is possible, thereby enabling improvement of the electrochemical characteristics, energy density, charge / discharge capacity, high-rate characteristics, and / or lifespan characteristics of the secondary battery.

[0058] Average particle size (D) of the sulfide-based solid electrolyte containing the above Br element 50 ) may be 0.4 μm or more to 1 μm or less, specifically 0.6 μm or more to 0.8 μm or less, but is not limited thereto.

[0059] The above average particle size (D 50 ) is the average particle size (D) described above. 50 It can be measured by the same method as the measurement method.

[0060] The content of the sulfide-based solid electrolyte containing the above-mentioned Br element in the coating layer may be 0.1 wt% or more to 20 wt% or less relative to the positive active material, preferably 0.1 wt% or more to 10 wt% or less, more preferably 0.1 wt% or more to 5 wt% or less, but is not limited thereto.

[0061] The above first solid electrolyte can be described in the same way as the sulfide-based solid electrolyte containing the aforementioned Br element.

[0062] The above conductive material or the first conductive material is used to impart conductivity to the positive active material composite, and can be used without special restrictions as long as it has electronic conductivity without causing chemical changes. Examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and may include one of these alone or a mixture of two or more.

[0063] The above conductive material may preferably include a carbon-based conductive material, specifically one or more selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber, and more preferably may include carbon black, and Super C65 may be used as an example. As an example, the carbon black may have a specific surface area of ​​62 m² / g or more to 65 m² / g or less, and / or may use carbon black with an iron content of less than 5 ppm. In addition, the carbon fiber may include carbon nanofibers (CNF).

[0064] The content of the conductive material in the coating layer may be 0.01 wt% or more to 1 wt% or less relative to the positive active material. For example, the content of the conductive material in the coating layer may fall within a range in which one selected from 0.01 wt% or more, 0.05 wt% or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, and 0.5 wt% or more relative to the positive active material has a lower limit, and one selected from 1 wt% or less, 0.9 wt% or less, 0.8 wt% or less, 0.7 wt% or less, 0.6 wt% or less, and 0.5 wt% or less has an upper limit, but is not limited thereto.

[0065] The weight ratio of the sulfide-based solid electrolyte containing Br element in the coating layer and the conductive material may be 200:1 or more to 1:100 or less, preferably 100:1 or more to 1:50 or less, more preferably 50:1 or more to 1:10 or less, 10:1 or more to 1:1 or less, 10:1 or more to 2:1 or less, or 10:1 or more to 5:1 or less, but is not limited thereto.

[0066] With respect to the first conductive material mentioned above, the same description regarding the conductive material mentioned above may be applied.

[0067] When a conductive material as described above is included in the coating layer, the electrochemical characteristics of the anode to which the anode active material composite as described above is applied can be improved, thereby enabling an increase in charge / discharge capacity, improvement in energy density, improvement in high-rate characteristics, and / or improvement in lifespan characteristics.

[0068] The coating layer may contain additional materials in addition to the sulfide-based solid electrolyte containing the Br element and the conductive material.

[0069] The thickness of the coating layer may be 1 nm or more to 300 nm or less, preferably 1 nm or more to 250 nm or less, 1 nm or more to 200 nm or less, 1 nm or more to 150 nm or less, 1 nm or more to 100 nm or less, 50 nm or more to 300 nm or less, 100 nm or more to 300 nm or less, 100 nm or more to 200 nm or less, or 100 nm or more to 150 nm or less, but is not limited thereto. When satisfying the thickness range as described above, it may be possible to improve the electrochemical characteristics, energy density, high-rate characteristics, and / or lifespan characteristics of the secondary battery. As for the thickness of the coating layer, for example, the distribution of halogen elements (Br, etc.) detected by SEM photography and EDS analysis of the cross-section of the cathode containing the cathode active material composite can be confirmed, but is not limited thereto, and other thickness measurement methods commonly used in the industry may also be used.

[0070] The coating layer is located on the surface of the positive active material and may be formed on an area of ​​10% or more to 99% or less of the surface of the positive active material, specifically 30% or more to 99% or less, more specifically more than 50% to 99% or 70% or more to 99% or less, but is not limited thereto. When the coating layer is formed on the surface of the positive active material in such an area range as described above, close interfacial contact between the positive active material and the solid electrolyte is possible, thereby enabling improvement of the electrochemical characteristics of the secondary battery, improvement of energy density, increase in charge / discharge capacity, improvement of high-rate characteristics and / or improvement of life characteristics.

[0071] The above positive active material may include primary particles, or secondary particles formed by the aggregation of primary particles. Alternatively, the above positive active material may include a single particle form, but is not limited thereto.

[0072] The meaning of the coating layer being located on the surface of the positive active material may include the coating layer being located on the surface of the positive active material of the primary particle, or it may include the coating layer being located on the surface of the positive active material of the secondary particle. Alternatively, it may include the coating layer being located on the surface of the positive active material of the single particle.

[0073] When the above coating layer is formed on the surface of the positive electrode active material, the process may be carried out by a simple mixing method of the coating material and the positive electrode active material, but preferably, it may be carried out by a mechanofusion method during a dry process. A specific method for manufacturing the coating layer is described later in the explanation of the method for manufacturing the positive electrode active material composite below.

[0074] One aspect of the present invention is to provide a positive electrode comprising the positive electrode active material complex.

[0075] The above-mentioned anode may include an anode current collector and an anode active material layer formed on at least one surface of the anode current collector, and the anode active material layer may include the aforementioned anode active material composite. In addition to the anode active material composite, the anode active material layer may further include a solid electrolyte, a conductive material, a binder and / or additives, etc.

[0076] In addition to the anode active material composite, the above-mentioned anode active material layer may further include a second solid electrolyte, a second conductive material, an anode binder and / or an anode additive, but is not limited thereto.

[0077] The above positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and may be made of, for example, copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), chromium (Cr), iron (Fe), zinc (Zn), indium (In), germanium (Ge), lithium (Li), magnesium (Mg), stainless steel (e.g., SUS), titanium (Ti), cobalt (Co), or an alloy thereof.

[0078] The anode current collector may have a thickness of 5 μm or more to 30 μm or less, and fine irregularities may be formed on the surface of the anode current collector to increase the adhesion of the anode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc. The anode current collector may be omitted depending on the case.

[0079] The solid electrolyte in the positive electrode active material layer or the second solid electrolyte may be the same as or different from the sulfide-based solid electrolyte containing Br element included in the coating layer. That is, the first solid electrolyte may be the same as or different from the second solid electrolyte.

[0080] The solid electrolyte included in the above-mentioned positive electrode active material layer may include, but is not limited to, sulfide-based solid electrolytes, oxide-based solid electrolytes, phosphoric acid-based solid electrolytes, polymer-based solid electrolytes, or halide-based solid electrolytes.

[0081] The above sulfide-based solid electrolyte contains sulfur atoms (S), has ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and may have electronic insulation properties. The above sulfide-based solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity, but may include other elements other than Li, S, and P depending on the purpose or case. As the above-mentioned sulfide-based solid electrolyte, for example, Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-H2S, Li2S-P2S5-H2S-LiCl, Li2S-LiI-P2S5, Li2S-LiI-Li2OP2S5, Li2S-LiBr-P2S5, Li2SLi2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2O5, Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, Li2S-GeS2-ZnS, Li2SGa2S3, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5, Li2S-GeS2-Sb2S5, Li2S-GeS2-Al2S3, Li2SSiS2, Li2S-Al2S3, Li2S-SiS2-Al2S3, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2-Li4SiO4, Li2SSiS2-Li3PO4, or Li 10 GeP2S 12 This may include the back.

[0082] The above sulfide-based solid electrolyte may be an argyrodite-based solid electrolyte. Preferably, the above argyrodite-based solid electrolyte may be an argyrodite-based solid electrolyte comprising one or more selected from Li6PS5F, Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0083] The above oxide-based solid electrolyte is, for example, LiPON, Li 3xLa(2 / 3-x)(1 / 3-2x)TiO3(0.04). <x<0.16), Li 1+x Al x The 2-x (PO4)3(0). <x<2), Li 1+x Al x Ge 2-x (PO4)3(0). <x<2), Li 1+x+y Al x The 2-x Si y P.S 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr, Ti)O3, Pb 1-x The x Zr 1-y The y O3(0≤x<1, 0≤y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3, HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, Nio, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x The y (PO4)3(0). <x<2, 0<y<3), Li x Al y The z (PO4)3(0). <x<2, 0<y<1, 0<z<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P.S 3-y O 12 (0≤x≤1 0≤y≤1), Li x The y TiO3(0). <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (Tea, Nb, Zr, 1≤x≤10), Li7La3Zr2O 12 , Li 3+x La3Zr 2-a M a O 12(M is Ga, W, Nb, Ta, or Al, 0 <a<2, 1≤x≤10) 또는 이들의 조합을 포함할 수 있다. 또한 산화물계 고체 전해질은 Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M-doped LLZO, M=Ga, W, Nb, Ta, or Al, 0 <a<2, 1≤x≤10) 중에서 선택된 가넷계(Garnet-type) 고체 전해질을 포함할 수 있다. 산화물계 고체 전해질은 결정질, 비정질, 유리질 또는 유리-세라믹일 수 있으며, 제조 방법 및 조성에 따라 다양한 결정 상태를 가질 수 있다.

[0084] The above phosphate-based solid electrolyte is a NASICON-type lithium-aluminum-titanium phosphate-based (LATP, Li 1+x Al x Ti 2-x (PO4)3), lithium-aluminum-germanium phosphate system (LAGP, Li 1.5 Al 0.5 Ge 1.5 It may include, but is not limited to, (PO4)3-based, lithium-silicon-titanium phosphate-based (LSTP, LiSiO2TiO2(PO4)3), or combinations thereof.

[0085] The above-mentioned polymer-based solid electrolyte is not particularly limited to any polymer material that is an ion-conducting material and is commonly used as a solid electrolyte material for all-solid-state batteries. The above-mentioned solid polymer electrolyte may include, for example, polyether-based polymers, polycarbonate-based polymers, acrylate-based polymers, polysiloxane-based polymers, phosphazene-based polymers, polyethylene oxide (PEO), polyethylene derivatives, alkylene oxide derivatives, phosphate ester polymers, polyaisation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, or polymers containing ionic dissociating groups. Alternatively, the above-mentioned polymer-based solid electrolyte may include, as a polymer resin, a branched copolymer, a comb-like polymer, and a cross-linked polymer resin, etc., in which an amorphous polymer such as polymethyl methacrylate (PMMA), polycarbonate, polysiloxane, and / or phosphazene is copolymerized as a comonomer to a polyethylene oxide (PEO) main chain.

[0086] The above-mentioned halide-based solid electrolyte may, for example, contain a halogen element as the main component of anion. Containing a halogen element as the main component of anion may mean that the proportion (molar ratio) of the halogen element is the highest among all anions constituting the halide-based solid electrolyte. The ratio of the halogen (X) element to all anions constituting the halide-based solid electrolyte may, for example, be 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol%. There may be one or more types of halogen elements. The halide-based solid electrolyte may not contain, for example, a sulfur element (S element). The halide-based solid electrolyte may contain, for example, a Li element, an M element (M is a metal other than Li), and an X element. X may, for example, be F, Cl, Br, I, or a combination thereof. The halide-based solid electrolyte may, for example, contain Br or Cl as X. The halide solid electrolyte may include a metal element such as Sc, Y, B, Al, Ga, or In as M. The composition of the halide solid electrolyte is, for example, Li 6-3a M a Br b Cl c (M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)일 수 있다. 할라이드 고체 전해질은 예를 들어 Li3YBr6, Li3YCl6, Li3YBr2Cl4 등일 수 있다.

[0087] Preferably, the solid electrolyte in the positive active material layer or the second solid electrolyte comprises a solid electrolyte that does not contain Br element, and as an example, the solid electrolyte in the positive active material layer may be an azirodite-based solid electrolyte comprising one or more selected from Li6PS5F, Li6PS5Cl, and Li6PS5I, but is not limited thereto.

[0088] The conductive material within the positive electrode active material layer or the second conductive material is used to impart conductivity to the electrode, and may be used without special restrictions as long as it possesses electronic conductivity without causing chemical changes. The conductive material included in the positive electrode active material layer may or may not include the same material as the first conductive material included in the coating layer of the positive electrode active material composite.

[0089] For example, the first conductive material may include a particulate conductive material, and the second conductive material may include a linear conductive material, but is not limited thereto. For example, carbon black may be used as the first conductive material and carbon nanofiber (CNF) may be used as the second conductive material, but is not limited thereto.

[0090] The anode binder in the anode active material layer above can serve to improve adhesion between anode active material composites and / or adhesion between anode active material composites and anode current collectors. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol (PVA), polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone (PVP), polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. For example, polytetrafluoroethylene (PTFE) can be used as a binder for the anode in the above-mentioned anode active material layer.

[0091] The above anode may further include an additive for the anode. The additive may further include, for example, fillers, coating agents, dispersants, thickeners, or ion conductivity aids, and may be used without limitation as long as it is a known material generally used for electrodes.

[0092] In addition to the aforementioned configuration, the anode may further include known configurations that can be included in the anode of a secondary battery.

[0093] The above-mentioned anode may be manufactured by coating a layer of anode active material onto an anode current collector, and in the case of the above-mentioned anode, the porosity may be 5% or more to 34% or less, preferably 7% or more to 33% or less, 8% or more to 32% or less, or 10% or more to 31% or less. In addition, based on the state before WIP, it may be 28% or more to 31% or less, preferably 29% or more to 30.5% or less, and based on the state after WIP, it may be 11% or more to 15% or less, preferably 11.5% or more to less than 14% or 12% or more to 13% or less, but is not limited thereto. The method for measuring porosity is not particularly limited and may be measured by known methods such as the BET (Brunauer-Emmett-Teller) measurement method or the mercury infiltration method (Hg porosimeter). For example, the true density can be derived using the density and fraction of each material introduced into the electrode, and then the porosity can be calculated based on the electrode's area, thickness, and weight along with the above value.

[0094] The anode containing the above-mentioned anode active material composite possesses excellent ionic conductivity and electronic conductivity. For example, the anode containing the above-mentioned anode active material composite may exhibit significantly improved ionic conductivity and electronic conductivity when compared to an anode active material composite that does not contain a conductive material in the coating layer or an anode active material composite that does not contain Br in the solid electrolyte of the coating layer.

[0095] One aspect of the present invention is to provide a secondary battery comprising the anode.

[0096] The secondary battery of the present invention may include a positive electrode, an electrolyte, and a negative electrode.

[0097] In the above secondary battery, the positive electrode is as described above.

[0098] In the above secondary battery, the negative electrode may include a negative current collector and a negative active material layer located on the negative current collector. In another example, the negative electrode may be a negative electrode for an anodeless battery in which the negative active material layer, such as a lithium metal layer, is not included immediately after battery manufacturing, but is formed through battery charging.

[0099] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the secondary battery, and for example, copper, stainless steel (e.g., SUS), aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated or coated with carbon, nickel, titanium, or silver, or aluminum-cadmium alloy may be used.

[0100] The above-mentioned negative current collector can typically have a thickness of 3 μm or more to 500 μm or less, and, similar to the positive current collector, fine irregularities can be formed on the surface of the negative current collector to strengthen the bonding force of the negative active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, or nonwoven fabric.

[0101] The above-mentioned cathode active material layer may optionally include a binder, a conductive material and / or additives, etc., together with the cathode active material. For example, the above-mentioned cathode active material layer may optionally include a third solid electrolyte, a cathode binder, a third conductive material and / or a cathode additive, etc., together with the cathode active material.

[0102] The above-mentioned negative electrode active material may be a negative electrode active material commonly used in secondary batteries. Examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, or amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Ag, Au, Si alloys, Sn alloys, or Al alloys; and SiO₂ βExamples include metal oxides capable of doping and dedoping lithium, such as SnO2, vanadium oxide, or lithium vanadium oxide (0<β≤2); or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Furthermore, the carbon material may include low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, or high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes. Additionally, the above-mentioned cathode active material layer may be omitted depending on the case. In this case, the cathode may include a cathode current collector, or may include the cathode current collector and a protective layer formed on the cathode current collector, but is not limited thereto.

[0103] The cathode active material layer may optionally include a third solid electrolyte, a cathode binder, a third conductive material and / or a cathode additive together with the cathode active material.

[0104] The binder (or negative electrode binder), conductive material (or third conductive material), and additive (negative electrode additive) included in the above-described negative electrode active material layer may be described in the same way as the positive electrode binder, second conductive material, and positive electrode additive included in the aforementioned positive electrode active material layer.

[0105] The above-mentioned positive electrode binder and negative electrode binder may be the same or different from each other.

[0106] The second conductive material and the third conductive material may be identical or different from each other.

[0107] For example, the description of the second solid electrolyte included in the aforementioned positive electrode active material layer can be applied in the same way to the third solid electrolyte.

[0108] The second solid electrolyte and the third solid electrolyte may be the same or different.

[0109] The above secondary battery includes a lithium secondary battery and may include a structure comprising a positive electrode, a negative electrode, an electrolyte, and / or a separator as a conventional secondary battery, but preferably may be an all-solid-state battery. For example, in the case where a solid electrolyte is used as the electrolyte in an all-solid-state battery, the separator may be omitted because the solid electrolyte acts as a separator. In addition, the above secondary battery may be a semi-solid-state battery, in which case it may include a separate polymer separator.

[0110] Examples of the above-mentioned conventional secondary batteries include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, or molten inorganic electrolytes that can be used when manufacturing lithium secondary batteries, but are not limited to these.

[0111] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0112] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene and fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a hydrocarbon group with a straight-chain, branched, or cyclic structure having 2 to 20 carbon atoms and may include a double bond, an directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.

[0113] The above lithium salt may be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It may be at least one selected from the group consisting of, and the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2.

[0114] The above-mentioned solid inorganic electrolyte may include oxide-based solid electrolytes, sulfide-based solid electrolytes, phosphoric acid-based solid electrolytes, or halide-based solid electrolytes. The above-mentioned description may apply equally to the oxide-based solid electrolyte, sulfide-based solid electrolyte, phosphoric acid-based solid electrolyte, or halide-based solid electrolyte.

[0115] In addition, the separator separates the negative and positive electrodes and provides a pathway for the movement of lithium ions; generally, any separator used in a secondary battery can be used without any special restrictions. Furthermore, if the electrolyte includes a solid electrolyte, the separator may include a solid electrolyte, and the solid electrolyte may perform the role of a separator.

[0116] Specifically, a porous polymer film made of a polyolefin-based polymer, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. A coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0117] The above secondary battery may be pouch-type, prismatic-type, or cylindrical, and its shape and size can be applied without restriction as long as it is a commonly used secondary battery.

[0118] Additionally, the secondary battery may further include a case capable of sealing the electrode assembly, such as a container, pouch, pack, or module, for housing the electrode assembly comprising the positive electrode, electrolyte, and negative electrode. The case may optionally further include a sealing member.

[0119] A secondary battery comprising a positive electrode containing the positive electrode active material composite of the present invention provides excellent charge / discharge capacity and / or charge / discharge efficiency. For example, the positive electrode containing the positive electrode active material composite may exhibit significantly improved charge / discharge capacity and efficiency when compared to a positive electrode active material composite that does not contain a conductive material in the coating layer or a positive electrode active material composite that does not contain Br in the solid electrolyte of the coating layer.

[0120] One aspect of the present invention may provide a method for manufacturing the anode active material composite.

[0121] Specifically, a method for manufacturing a positive electrode active material composite may be provided, comprising the steps of: preparing a composition for forming a positive electrode active material composite by mixing a positive electrode active material, a conductive material, and a sulfide-based solid electrolyte containing Br element; and forming a coating layer on the surface of the positive electrode active material by mixing the composition for forming the positive electrode active material composite at a speed greater than 3400 rpm and less than 3800 rpm. When such mixing speeds are satisfied, close interfacial contact between the positive electrode active material and the solid electrolyte is made possible, thereby enabling improvement of the electrochemical characteristics, energy density, charge / discharge capacity, high-rate characteristics, and / or lifespan characteristics of the secondary battery.

[0122] The step of preparing the composition for forming the anode active material composite may include, for example, the step of preparing the composition for forming the anode active material composite by mixing the anode active material, the first conductive material, and the first solid electrolyte.

[0123] The above description may be applied in the same way to the positive active material, the first conductive material, and the first solid electrolyte. The solid electrolyte may be an azirodite-based solid electrolyte containing Br element.

[0124] The step of forming a coating layer on the surface of the above-mentioned positive active material may be by a mechanofusion method during a dry process.

[0125] For example, the above mechanofusion method can be performed using, for example, Hosakawa Micron’s nobilta equipment.

[0126] After introducing the above-mentioned positive active material, conductive material, and sulfide-based solid electrolyte mixture containing Br element into a container, the container is rotated to move the mixture to the inner wall of the container by centrifugal force. Subsequently, a strong shear force is applied by an arm head that is close to the inner wall of the container with a small gap, and the conductive material and solid electrolyte can be strongly coated on the surface of the positive active material through the interaction between the surfaces of the mixtures.

[0127] Preferably, in the step of mixing the composition for forming the anode active material composite, the mixing speed can be controlled to a range of more than 3400 rpm and less than 3800 rpm, and more preferably to a range of more than 3500 rpm and less than 3800 rpm. For example, if the container rotation speed is set to 3400 rpm or less, electrolyte particles may remain on the surface and the coating may not proceed sufficiently, and if the mixing speed is 3800 rpm or more, some of the active material particles may be broken.

[0128] In the following, the present invention is described in detail with reference to examples to specifically explain the disclosure of the present invention as described above and the intended functions and effects of the present invention. However, the examples may be modified in various different forms, and the scope of this specification is not to be interpreted as being limited only to these examples. It is emphasized that the examples are provided to represent the present invention and to explain it more specifically to those skilled in the art.

[0129] Examples and Comparative Examples

[0130] Example 1. Preparation of a positive electrode active material composite

[0131] For the preparation of the cathode active material composite of the present invention, NCM811 is used as the cathode active material and Li6PS5Cl, a Br-doped azirodite-based material, is used as the solid electrolyte. 1-x Br x (0 <x≤0.5), 탄소계 도전재로 Super C65를 준비하였다. Li6PS5Cl 1-x Br x Super C65 and NCM811 were prepared at a ratio of 3 wt% and 0.5 wt%, respectively, relative to the cathode active material NCM811, and a cathode active material composite was manufactured by coating the cathode active material particles with the solid electrolyte and conductive material using the mechanofusion method during a dry process. Specifically, the mixing of the cathode active material, solid electrolyte, and conductive material was carried out after cooling the container temperature of the mixer to 35°C or lower, and the mixing speed was controlled to start at 3000 rpm and increase by 100 rpm every minute so that it could finally be mixed at 3600 rpm.

[0132] Comparative Example 1.

[0133] A cathode active material composite was prepared in the same manner as in Example 1, except that the conductive material Super C65 was excluded from Example 1.

[0134] Comparative Example 2.

[0135] A positive electrode active material was prepared using only NCM 811 particles identical to those in Example 1, without coating with a solid electrolyte or conductive material.

[0136] Comparative Example 3.

[0137] Li6PS5Cl, a Br-doped azirodite-based solid electrolyte in Example 1 1-x Br x A cathode active material composite was prepared in the same manner as in Example 1, except that Li6PS5Cl, an argyrodite-based material not doped with Br, was used instead.

[0138] Experimental Example

[0139] Experimental Example 1. Confirmation of coating morphology of the cathode active material composite

[0140] We intended to verify the coating morphology of the cathode active material composite of Example 1. Specifically, we attempted to verify the morphology of the formed coating layer by taking SEM (scanning electron microscope) images of the cathode active material composite of Example 1. As a result, as can be seen in Figure 1, it was confirmed that the coating layer of the cathode active material composite of Example 1 was uniformly formed on the particle surface.

[0141] Experimental Example 2. Morphological evaluation of cathode active material composite according to mixing rate in dry process for manufacturing cathode active material composite

[0142] The aim was to identify a manufacturing method for forming a uniform and stable coating layer when manufacturing the cathode active material composite of the present invention. Specifically, the coating layer formation mode was determined according to the mixing speed when coating was performed by the mechanofusion method; otherwise, the cathode active material composite was manufactured in the same manner as in Example 1. When performing the mechanofusion method for coating layer formation, the final mixing speeds were set to 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, and 3800 rpm, respectively. SEM images were taken of the coated cathode active material composites to evaluate the coating morphology according to the final mixing speed. The specific method of taking SEM images was the same as that performed in Experimental Example 1, and the results are shown in Fig. 2. Specifically, FIG. 2(a) is an SEM image of a positive electrode active material particle before the formation of a coating layer, and FIG. 2(b) to FIG. 2(f) are SEM images of positive electrode active material composites prepared by setting the mixing speed to 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm, and 3800 rpm, respectively.

[0143] As a result, according to FIGS. 2(b) to 2(d), when the mixing speed is set to 3400 rpm or less, residual electrolyte particles are found on the surface of the positive active material particles, indicating that the coating is not sufficiently advanced. According to FIG. 2(f), when the mixing speed is set to 3800 rpm or more, it is confirmed that some of the positive active material composite particles are broken. On the other hand, according to FIG. 2(e), when the mixing speed is set to 3600 rpm, it is confirmed that a coating layer is formed uniformly over the entire surface of the positive active material particles.

[0144] Experimental Example 3. Cross-sectional SEM images and EDS analysis to confirm coating layer formation

[0145] After taking SEM images of the cathode active material composite prepared in Example 1, EDS analysis (Energy-dispersive X-ray spectroscopy) was performed on it. The EDS analysis was performed for Ni, S, and C, respectively, and the results can be seen in Figures 3(a) to 3(c). Looking at Figure 3, it can be seen that S and C are distributed in the region where Ni was detected, indicating that a coating layer containing the conductive material and solid electrolyte is formed on the surface of the cathode active material particles.

[0146] Experimental Example 4. Evaluation of Anode Porosity

[0147] Each of the cathode active material composites prepared in Example 1 and Comparative Examples 1 to 3 was mixed with Li6PS5Cl, carbon nanofiber (CNF), and polytetrafluoroethylene (PTFE), and then molded into a sheet to prepare a cathode active material layer, and then the cathode active material layer was laminated onto an aluminum foil with a thickness of 18 μm to prepare a cathode.

[0148] A lithium metal was prepared as the cathode and an LPSCl film as the solid electrolyte layer, and the anode, solid electrolyte layer, and cathode were sequentially stacked and WIP pressurized at 500 MPa to manufacture an all-solid-state battery. The WIP pressurization process was carried out in a WIP chamber under a temperature condition of 70°C by increasing the pressure to 500 MPa.

[0149] At this time, in order to verify the porosity of the anode, the thickness and weight of the anode active material layer were measured before and after WIP pressurization, respectively, and the porosity was calculated by substituting the corresponding values ​​into the following formula 1 along with the anode active material layer area and the loading layer density. The results are shown in Table 1 and Figure 4 below. The loading layer density refers to the sum of the values ​​obtained by multiplying the true density by the composition for each component of the anode active material layer.

[0150] [Formula 1]

[0151] Porosity (%) = (1 - (Weight of positive active material layer / (Area of ​​positive active material layer × Thickness of positive active material layer)) / Loading layer density) × 100

[0152] Classification Porosity before WIP (%) Porosity after WIP (%) Example 1 30.2 12.3 Comparative Example 2 34.8 14.0

[0153] As can be seen in Figure 4, it was confirmed that the porosity of the cathode prepared using the cathode active material composite of Example 1 was significantly lower than that of the cathode prepared using the cathode active material of Comparative Example 2. Accordingly, this suggests that a secondary battery with high energy density can be manufactured when the cathode is prepared using the cathode active material composite of the example.

[0154] Experimental Example 5. Evaluation of Anode Conductivity (EIS Measurement)

[0155] Electrochemical Impedance Spectroscopy (EIS) analysis was performed on each anode corresponding to Example 1 and Comparative Example 1 prepared in Experimental Example 4. Specifically, EIS analysis was repeated three times for each anode corresponding to Example 1 and Comparative Example 1, and the results of each analysis were shown as a Nyquist plot in Fig. 5. Electromagnetic resistance values ​​were derived through the Nyquist plot, and the electron conductivity of each anode was calculated based on the electromagnetic resistance values ​​and the numerical values ​​of the electrode area and thickness. The average value of the calculated values ​​obtained by repeating the analysis three times for each anode is shown in Table 2 below.

[0156] Classification Electron Conductivity (S / cm) Example 12.70*10 -5 Comparative Example 18.70*10 -6

[0157] Through Table 2, it was confirmed that the electronic conductivity was significantly improved in Example 1 compared to Comparative Example 1 by reducing the charge transfer resistance. Thus, it was confirmed that it is possible to manufacture a cathode with high electronic conductivity when using the cathode active material composite of Example 1.

[0158] Experimental Example 6. Evaluation of Charge / Discharge Capacity

[0159] The all-solid-state battery prepared in Experimental Example 4 was charged to 4.25V relative to the lithium metal reference electrode (Li / Li+) under a temperature condition of 60°C and a constant current-constant voltage (CC-CV) condition of 0.1C. Subsequently, a constant current discharge (CC) was performed down to 3.0V under the same current condition (0.1C) to complete the first cycle (1 st The charge-discharge test of the cycle was completed. The resulting charge-discharge curve is shown in Fig. 6, and the specific measured values ​​for charge-discharge capacity are shown in Table 3 below.

[0160] Category 1 stCycle Charge / Discharge Capacity Charge Capacity (mAh / g) Discharge Capacity (mAh / g) Example 1 228.3 195.7 Comparative Example 1 209.4 184.2 Comparative Example 2 216.7 191.0 Comparative Example 3 193.7 171.8

[0161] It was confirmed that when the cathode active material composite of Example 1 is used as the cathode, it has a larger charge / discharge capacity compared to when the cathode active material composites of Comparative Examples 1 to 3 are used. Thus, it was confirmed that when the cathode active material composite of Example 1 is used, an all-solid-state battery with improved charge / discharge capacity can be manufactured.

[0162] Experimental Example 7. Evaluation of Capacity Retention Rate by C-Rate

[0163] The all-solid-state battery prepared in Experimental Example 4 was activated by charging it to 4.2V at 60°C under CC / CV and 0.1C conditions, and then discharging it to 3.0V under CC and 0.1C conditions. Subsequently, the capacity retention rate, calculated by dividing the discharge capacity measured through a charging and discharging protocol at 0.33C, 0.5C, 1C, and 0.1C by the discharge capacity at 0.1C, was measured, and the results are shown in Figure 7 below.

[0164] In particular, the ratio of the discharge capacity at 1C to the discharge capacity at 0.1C (retention(%)) was evaluated, and the results are shown in Table 4 below.

[0165] Classification Ratio of 1C Discharge Capacity to 0.1C Discharge Capacity (%) Example 1 96.5 Comparative Example 1 95.9 Comparative Example 2 93.9 Comparative Example 3 89.0

[0166] Experimental Example 8. Evaluation of Capacity Retention Rate According to the Number of Charge / Discharge Cycles

[0167] For the all-solid-state battery prepared in Experimental Example 4, it was charged at 60°C under CC / CV, 0.5 C conditions, 4.2 V, and 0.05 C cut conditions, then activated by discharging to 2.5 V under CC, 0.5 C conditions, and then charged and discharged 90 times under the same conditions. The retention rate relative to the initial capacity according to the number of charge-discharge cycles was measured and is shown in Figure 8, and the results of evaluating the capacity retention rate after 90 charge-discharge cycles relative to the initial capacity are shown in Table 5 below.

[0168] Classification Capacity Retention Rate (%) Example 1 96.3 (90 cycles) Comparative Example 1 95.5 (90 cycles) Comparative Example 2 93.1 (90 cycles) Comparative Example 3 94.1 (34 cycles)

Claims

1. Anode active material; and A positive electrode active material composite comprising a coating layer formed on the surface of the above positive electrode active material, The above coating layer is an anode active material composite comprising a conductive material and a sulfide-based solid electrolyte containing Br element.

2. In Paragraph 1, A positive electrode active material composite comprising a sulfide-based solid electrolyte containing the above-mentioned Br element, wherein the sulfide-based solid electrolyte containing the above-mentioned Br element comprises an azirodite-based solid electrolyte containing the above-mentioned Br element.

3. In Paragraph 1, A positive electrode active material complex comprising a sulfide-based solid electrolyte containing the above-mentioned Br element, wherein the sulfide-based solid electrolyte comprises a compound of the following chemical formula 1: [Chemical Formula 1] Li a PS b X c Br d In the above chemical formula 1, X is at least one selected from F, Cl, and I, and 5≤a≤6, 4≤b≤5, 0 <c≤1, 0<d≤1 이다.

4. In Paragraph 1, A cathode active material composite having a content of a sulfide-based solid electrolyte containing the above Br element of 0.1 weight% or more to 5 weight% or less relative to the above cathode active material.

5. In Paragraph 1, The above conductive material is a positive electrode active material composite comprising a carbon-based conductive material.

6. In Paragraph 5, The above-mentioned carbon-based conductive material comprises one or more selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber, forming an anode active material composite.

7. In Paragraph 1, A cathode active material composite having a conductive material content of 0.01 weight% or more to 1 weight% or less relative to the cathode active material.

8. In Paragraph 1, A positive electrode active material composite having a coating layer thickness of 1 nm or more to 300 nm or less.

9. In Paragraph 1, A positive electrode active material composite, wherein the coating layer is formed on an area corresponding to 10% or more to 99% or less of the surface of the positive electrode active material.

10. A positive electrode comprising a positive electrode active material complex according to any one of claims 1 to 9.

11. An anode according to claim 10, wherein the porosity of the anode is 5% or more to 34% or less.

12. A secondary battery comprising the positive electrode of paragraph 10.

13. A step of preparing a composition for forming an anode active material composite by mixing an anode active material, a conductive material, and a sulfide-based solid electrolyte containing Br element; and A method for manufacturing an anode active material composite, comprising the step of mixing the above-mentioned composition for forming an anode active material composite at a speed greater than 3,400 rpm and less than 3,800 rpm to form a coating layer on the surface of the anode active material.

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