Anode active material, anode and lithium ion battery comprising the same

Abstract

The present invention relates to a negative electrode active material (100) that can be used in a lithium-ion battery, more specifically, to a negative electrode active material comprising a negative electrode material (110) and a coating portion (120) formed on the outside of the surface of the negative electrode material, wherein the coating portion comprises an oxide-based solid electrolyte.

Description

Technology Field

[0001] The following various embodiments relate to a negative electrode active material that may be included in a lithium-ion battery, a negative electrode including the same, and a lithium-ion battery. Background Technology

[0003] Lithium-ion batteries (LIBs) can achieve high energy density while remaining lightweight, and are currently widely used as the primary power source for portable devices such as laptops and mobile devices including smartphones; furthermore, active research is underway to apply them to various fields, ranging from transportation methods like electric vehicles to large-capacity energy storage systems.

[0004] As part of this research direction, various types of lithium-ion batteries are being developed to optimize their electrochemical performance and stability. Among these, all-solid-state batteries, which incorporate solid electrolytes, are attracting attention as candidates for next-generation rechargeable batteries due to their potentially high energy density and enhanced stability. Specifically, the introduction of solid electrolytes not only improves design capabilities compared to liquid electrolytes but also significantly resolves safety-related issues associated with lithium-ion batteries, such as fire hazards, by replacing liquid electrolytes that carry an inherent risk of explosion.

[0005] At this time, sulfide-based solid electrolytes and oxide-based solid electrolytes are the two main types of inorganic solid electrolytes that can be used in the aforementioned all-solid-state batteries, and among these, sulfide-based solid electrolytes are known to be the most promising candidate material for solid electrolytes to be used in next-generation all-solid-state batteries, in that their lithium ion conductivity is closest to that of liquid electrolytes.

[0006] Meanwhile, carbon-based anode materials with stable crystal structures are currently primarily used as anode materials in lithium-ion batteries; however, their direct application in all-solid-state batteries is restricted due to the problem that they react with sulfide-based solid electrolytes to decompose them. Accordingly, the development of non-carbon anode materials is also being considered; however, the development of anode material technologies other than carbon-based (graphite, amorphous carbon) is significantly delayed. Furthermore, silicon-based anode materials, considered a next-generation material, are not suitable for use in sulfide-based all-solid-state batteries because they involve a carbon coating on the silicon surface to increase conductivity and suppress reactivity with the electrolyte.

[0007] Therefore, for the commercialization of all-solid-state batteries, it is necessary to develop anode materials capable of realizing excellent electrochemical properties, such as high electrical capacity and superior capacity retention rate, without causing reaction and decomposition problems, particularly with sulfide-based solid electrolytes. The problem to be solved

[0009] To solve the above-mentioned problems, a cathode active material is provided that includes a cathode material and a coating portion formed on the outer surface of the cathode material, wherein the coating portion includes an oxide-based solid electrolyte, thereby enabling the suppression of a decomposition reaction between the cathode material and the solid electrolyte.

[0010] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0012] An anode active material (100) according to one embodiment comprises an anode material (110) and a coating portion (120) formed on the outside of the surface of the anode material, and the coating portion may comprise an oxide-based solid electrolyte.

[0013] The oxide-based solid electrolyte may include one or more of LISICON (Lithium Super Ionic Conductor)-based compounds, LLZO (Lithium Lanthanum Zirconium Oxide)-based compounds, LLTO (Lithium Lanthanum Titanium Oxide)-based compounds, LATP (Lithium Aluminum Titanium Phosphate)-based compounds, and LiPON (Lithium Phosphorous Oxynitrides)-based compounds.

[0014] The above LISICON-based compound is Li (4-x) Si (1-x) P x O4, Li (4-x) Si (1-x) Al x O4, Li (4-x) Si (1-x) Ge x O4, Li (2+2x) Zn (1-x) GeO4 and Li (3+x) Ge x V (1-x) O4 (wherein for each compound, 0 <x<1)중 하나 이상을 포함할 수 있다.

[0015] The oxide-based solid electrolyte may be 1 to 10 weight percent of the total weight of the negative electrode active material.

[0016] The above coating portion may further include a binder.

[0017] The binder may include one or more of PAA (Poly acrylic acid), PI (Polyimide), SBR (Styrene Butadiene Rubber), CMC (Carboxymethyl Cellulose), PVDF (Polyvinylidene fluoride), and PAN (Polyacrylonitrile).

[0018] The weight ratio of the oxide-based solid electrolyte and the binder may be 1:1 to 10:1.

[0019] The above cathode material may include one or more of a carbon-based cathode material and a metal-based cathode material.

[0020] The above carbon-based cathode material may include one or more of artificial graphite, natural graphite, MCMB (Mesocarbon microbead), hard carbon, soft carbon, graphene, reduced graphene oxide, carbon nanotube, carbon fiber, activated carbon, and carbon black.

[0021] The above metal-based cathode material may include at least one of a metal selected from the group consisting of Si, Ge, Sn, Mg, Al, Ca, Fe, Mn, Co, Ni, Zn, and Pb, an oxide of the metal, and an alloy of the metal.

[0022] The above cathode material may have a core-shell structure.

[0023] A cathode according to one embodiment may include the cathode active material, the conductive material, and the cathode binder.

[0024] A lithium-ion battery (1) according to one embodiment may include the negative electrode, the negative electrode current collector, the positive electrode, the positive electrode current collector, and the sulfide-based solid electrolyte.

[0025] The above sulfide-based solid electrolyte is Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3PS4, Li 10 GeP2S 12 , Li7P3S 11 It may include one or more of Li2S-P2S5Li2S-SiS2, Li3PO4-P2S5, Li3PO4-Li2S-SiS2 and Thio-LISICON-based compounds. Effects of the invention

[0027] A negative electrode active material according to one embodiment comprises a negative electrode material and a coating portion formed on the outer surface of the negative electrode material, wherein the coating portion comprises an oxide-based solid electrolyte, thereby minimizing the decomposition reaction between the negative electrode material and the sulfide-based solid electrolyte, which reduces the increase in resistance due to the use of the battery and improves the cycle life.

[0028] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention. Brief explanation of the drawing

[0030] FIG. 1 is a diagram showing a negative electrode active material (100) according to one embodiment of the present invention. FIG. 2 is a diagram showing that the negative electrode material among the negative electrode active material (100) according to one embodiment of the present invention has a core-shell structure. FIG. 3 is a diagram showing the structure of a lithium-ion battery (1) including a negative electrode active material according to one embodiment of the present invention. FIG. 4 is a graph showing the capacity retention rate according to the number of cycles for a compressed cell containing a negative electrode active material of an example and a comparative example according to the present invention. Specific details for implementing the invention

[0031] Embodiments are described in detail below. However, various modifications may be made to the embodiments, and thus the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, and substitutions to the embodiments are included within the scope of the rights.

[0032] To those skilled in the art, the scope of the present invention is not limited by these embodiments according to the gist of the invention.

[0033] The terms used in the embodiments are for illustrative purposes only and should not be interpreted as intended to be limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0034] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the embodiments pertain. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0035] In addition, when describing the embodiments, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the embodiments, such detailed description is omitted.

[0036] In addition, terms such as first, second, A, B, (a), (b), etc. may be used when describing the components of the embodiments. These terms are used only to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by the terms.

[0037] Components included in any one embodiment and components having common functions shall be described using the same names in other embodiments. Unless otherwise stated, the descriptions given in any one embodiment may also apply to other embodiments, and specific descriptions shall be omitted to the extent of overlap.

[0038] Throughout the specification, when a part is described as "including" a certain component, this means that it does not exclude other components but may include additional components.

[0040] According to one embodiment, the negative electrode active material (100) according to the present invention comprises a negative electrode material (110) and a coating portion (120) formed on the outside of the surface of the negative electrode material, and the coating portion may comprise an oxide-based solid electrolyte.

[0041] In an all-solid-state battery containing a sulfide-based solid electrolyte, if the negative electrode material contains carbon in particular, a type of decomposition reaction may occur at the interface between the negative electrode material and the solid electrolyte during battery operation, and as a result, decomposition reaction products such as Li2S may be generated around the negative electrode active material.

[0042] In this case, decomposition reactants such as Li2S are substances with very high electrical resistance and can cause a rapid decrease in the electrical conductivity of the negative electrode active material. Furthermore, due to the aforementioned decomposition reaction, the structure of the sulfide-based solid electrolyte itself may collapse or its absolute amount may decrease, leading to a problem where the ionic conductivity in the electrolyte region also decreases. Such a decrease in electrical and ionic conductivity causes an increase in the overall resistance of the battery, which can be a major cause of the reduction in electrochemical characteristics, such as the battery's electrical capacity and cycle life; the severity of this impact may intensify as the battery's operating time increases.

[0043] Accordingly, the negative electrode active material of the present invention minimizes the possibility of physical contact and chemical reaction between the negative electrode material and the sulfide-based solid electrolyte by introducing a coating portion containing an oxide-based solid electrolyte onto the surface of the negative electrode material, thereby reducing the formation of lithium sulfide and the decomposition of the sulfide-based solid electrolyte during battery operation, and as a result, the electrical conductivity and cycle life of the negative electrode containing the negative electrode active material and the lithium-ion battery containing the negative electrode could be improved.

[0044] FIG. 1 shows a cross-sectional structure of a negative electrode active material (100) according to one embodiment of the present invention. According to FIG. 1, the negative electrode active material has a negative electrode material (110) at its center, and a coating portion (120) containing an oxide-based solid electrolyte on the surface of the negative electrode material. FIG. 1 is illustrated as if the coating portion completely surrounds the negative electrode material, but it is not necessarily limited to this, and the coating portion may surround only a part of the negative electrode material.

[0045] As a method for coating the above oxide-based solid electrolyte onto the cathode material, general oxide coating methods such as high-speed stirring, spray drying, liquid-phase mixing, ball milling (mechanochemical method), and precipitation may be used, but are not necessarily limited thereto.

[0047] According to one embodiment, the oxide-based solid electrolyte may include one or more of LISICON (Lithium Super Ionic Conductor)-based compounds, LLZO (Lithium Lanthanum Zirconium Oxide)-based compounds, LLTO (Lithium Lanthanum Titanium Oxide)-based compounds, LATP (Lithium Aluminum Titanium Phosphate)-based compounds, and LiPON (Lithium Phosphorous Oxynitrides)-based compounds.

[0048] According to one embodiment, the LISICON-based compound is Li (4-x) Si(1-x) P x O4, Li (4-x) Si (1-x) Al x O4, Li (4-x) Si (1-x) Ge x O4, Li (2+2x) Zn (1-x) GeO4 and Li (3+x) Ge x V (1-x) One or more of O4 (provided that for each compound, 0 <x<1)을 포함할 수 있으며, 바람직하게는 Li (4-x) Si (1-x) P x O4(where 0 <x<1)일 수 있고, 더욱 바람직하게는 Li 3.5 Si 0.5 P 0.5 It can be O4 (i.e., x = 0.5).

[0049] According to one embodiment, the oxide-based solid electrolyte may be 1 to 10 weight% relative to the total weight of the negative electrode active material, preferably 2 to 9 weight%, more preferably 3 to 8 weight%, and most preferably 4 to 6 weight%.

[0050] If the oxide-based solid electrolyte content is below the lower limit of the above range, the effect of reducing the sulfide-based solid electrolyte decomposition reaction and the resulting lithium sulfide formation cannot be reduced to the desired level, and if it exceeds the upper limit of the above range, the electrical conductivity between the negative electrode materials may decrease due to the excessive increase in the coating portion, and consequently, the resistance of the entire battery may increase.

[0052] According to one embodiment, the coating portion may further include a binder.

[0053] The binder not only enhances the adhesion between the surface of the cathode material and the oxide-based solid electrolyte to improve the mechanical durability of the cathode active material or the cathode, but also serves to further reduce the surface area where the cathode material and the sulfide-based solid electrolyte can come into contact, compared to the case where the coating part contains only the oxide-based solid electrolyte. Due to this reduction in the contact surface area, the decomposition reaction between the cathode material and the sulfide-based solid electrolyte can be more effectively reduced, which can further lower the overall resistance of the battery and further improve battery life.

[0054] The above binder may be a polymer material that has affinity for the cathode material and the oxide-based solid electrolyte, and it is preferable that it does not dissolve in non-polar solvents, and it does not necessarily have to be the same as the cathode binder that may be included in the cathode.

[0055] According to one embodiment, the binder may include one or more of PAA (Poly acrylic acid), PI (Polyimide), SBR (Styrene Butadiene Rubber), CMC (Carboxymethyl Cellulose), PVDF (Polyvinylidene fluoride), and PAN (Polyacrylonitrile), and preferably may be PAA.

[0056] According to one embodiment, the weight ratio of the oxide-based solid electrolyte and the binder may be 1:1 to 10:1, preferably 2:1 to 9:1, more preferably 3:1 to 8:1, even more preferably 4:1 to 6:1, and most preferably 5:1.

[0057] If the weight ratio of the oxide-based solid electrolyte and the binder is below the lower limit of the above range, the binder content is excessive, which may cause a sharp decrease in electrical conductivity and ionic conductivity between the cathode materials; if it exceeds the upper limit of the above range, the binder is relatively very small compared to the oxide-based solid electrolyte, which may reduce the mechanical durability of the cathode active material or the cathode caused by the binder.

[0058] As a method for coating the above binder onto the cathode material, commonly used coating methods such as high-speed stirring, spray drying, liquid mixing, ball milling (mechanochemical method), and precipitation may be used, but are not necessarily limited thereto; the binder may be coated simultaneously with the oxide-based solid electrolyte or added to the cathode material sequentially.

[0060] According to one embodiment, the cathode material may include one or more of a carbon-based cathode material and a metal-based cathode material.

[0061] The cathode material can generally be a cathode material suitable for use in lithium-ion batteries, and it is desirable to include carbon in whole or in part. Additionally, the cathode material may be in the form of flakes and may have a structure containing internal pores.

[0062] According to one embodiment, the carbon-based cathode material may include one or more of artificial graphite, natural graphite, MCMB (Mesocarbon microbead), hard carbon, soft carbon, graphene, reduced graphene oxide, carbon nanotube, carbon fiber, activated carbon, and carbon black.

[0063] According to one embodiment, the metal-based cathode material may include at least one of a metal selected from the group consisting of Si, Ge, Sn, Mg, Al, Ca, Fe, Mn, Co, Ni, Zn, and Pb, an oxide of the metal, and an alloy of the metal.

[0064] When the above cathode material is silicon, D measured by laser diffraction 50 (Particle size at 50% cumulative percentage) can be 80 to 200 nm.

[0066] According to one embodiment, the cathode material may have a core-shell structure comprising a core portion (111) and a shell portion (112) formed outside the surface of the core portion.

[0067] FIG. 2 shows a cross-sectional structure of a negative electrode active material (100) according to one embodiment of the present invention, wherein the negative electrode material (110) has a core-shell structure. According to FIG. 2, the negative electrode active material comprises a negative electrode material (110) including a core portion (111) located at the center and a shell portion (112) covering the surface of the core portion, and a coating portion (120) may exist in a form covering the surface of the negative electrode material. Although the coating portion is depicted as covering the entire negative electrode material, it is not necessarily limited thereto, and the coating portion may be in a form covering only a part of the negative electrode material.

[0068] In the case of the core portion above, it may include one or more of the carbon-based cathode material and the metal-based cathode material, and may exhibit a structure including pores; if the metal-based cathode material is included in the core portion, it may be in the form of flakes. Additionally, if silicon is included in the core portion, D measured by laser diffraction 50 (Particle size at 50% cumulative percentage) can be 80 to 200 nm.

[0069] In the case of the shell portion above, it may include one or more of the carbon-based cathode material and the metal-based cathode material, and it is preferable that it be composed mainly of carbon. Although FIG. 2 is illustrated as if the shell portion completely surrounds the core portion, it is not necessarily limited to this, and the shell portion may be in a form that surrounds only a part of the core portion.

[0071] According to one embodiment, the cathode according to the present invention may include a cathode active material, a conductive material, and a cathode binder according to the present invention.

[0072] The conductive material may be carbon materials such as Super P, carbon black (including acetylene black), carbon nanotubes, carbon fibers, graphite, and graphene, but is not necessarily limited thereto, and two or more types of conductive materials may be mixed and used. Also, the cathode binder may include PAA (Poly acrylic acid), PI (Polyimide), SBR (Styrene Butadiene Rubber), CMC (Carboxymethyl Cellulose), PVDF (Polyvinylidene fluoride), and PAN (Polyacrylonitrile), but is not necessarily limited thereto, and two or more types of binders may be mixed and used, and it does not necessarily have to be the same as the cathode binder included in the coating part.

[0074] According to one embodiment, the lithium-ion battery (1) according to the present invention may be an all-solid-state battery and may include a negative electrode, a negative electrode current collector, a positive electrode current collector, and a sulfide-based solid electrolyte according to the present invention.

[0075] According to one embodiment, the sulfide-based solid electrolyte is Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3PS4, Li 10 GeP2S 12 , Li7P3S 11It may include one or more of Li2S-P2S5Li2S-SiS2, Li3PO4-P2S5, Li3PO4-Li2S-SiS2 and Thio-LISICON-based compounds, preferably one or more of Li6PS5Cl, Li6PS5Br, and Li6PS5I having an argyridite structure, and most preferably Li6PS5Cl.

[0077] The present invention will be explained in more detail below through examples. The following examples are described for the purpose of illustrating the present invention and do not limit the scope of the present invention.

[0079] - Preparation Example 1: Preparation of cathode active material

[0080] <Example 1-1>

[0081] LISICON-type oxide-based solid electrolyte (Li relative to the total weight of the negative electrode active material) 3.5 Si 0.5 P 0.5 A solution containing 5 wt% O4 and 1 wt% PAA (Poly acrylic acid) was prepared, and then a negative electrode active material was prepared by coating the surface of artificial graphite with the solution containing an oxide-based solid electrolyte and a binder using a spray drying method.

[0082] <Example 1-2>

[0083] LISICON-type oxide-based solid electrolyte (Li) on artificial graphite 3.5 Si 0.5 P 0.5 O4) was added at 5% by weight relative to the total weight of the cathode active material, and then an oxide-based solid electrolyte was coated onto the surface of artificial graphite using a high-speed stirring method to produce a cathode active material.

[0084] <Examples 1-3> (Comparative Example 1)

[0085] Artificial graphite was used as is as the negative electrode active material.

[0086] <Example 2-1>

[0087] A negative electrode active material was prepared in the same manner as in Example 1-1, except that instead of artificial graphite, the negative electrode material had a core-shell structure in which the core part was made of silicon and the shell part was made of carbon.

[0088] <Example 2-2>

[0089] A negative electrode active material was prepared in the same manner as in Examples 1-2 above, except that instead of artificial graphite, the negative electrode material had a core-shell structure in which the core part was made of silicon and the shell part was made of carbon.

[0090] <Example 2-3> (Comparative Example 2)

[0091] A core-shell structured cathode material, in which the core is made of silicon and the shell is made of carbon, was used as the cathode active material.

[0093] - Preparation Example 2: Preparation of an all-solid-state battery powder cell

[0094] A cathode slurry was prepared by uniformly mixing the cathode active material of the examples according to Manufacturing Example 1, SWCNT (Single-walled carbon nanotube) conductive material, CMC (Carboxymethyl cellulose) binder, and SBR (Styrene Butadiene Rubber) binder in a weight ratio of 96.95 : 0.05 : 1 : 2, respectively.

[0095] Then, the prepared cathode slurry was coated onto a copper foil current collector with a thickness of 20 μm, and the coated electrode plate was dried at 120°C for 10 minutes and then rolled to produce a cathode.

[0096] Finally, along with the above-mentioned cathode, Li6PS5Cl was used as a sulfide-based solid electrolyte and lithium metal was used as a counter electrode to manufacture the compaction cells of each embodiment, and the structure was shown as in Fig. 3.

[0098] - Experimental Example 1: Evaluation of Powder Cell Characteristics

[0099] (1) Evaluation method

[0100] 1) For the compressed powder cells of the examples according to Preparation Example 2, the battery characteristics were evaluated at a temperature of 25°C in a chamber under a nitrogen atmosphere. Each compressed powder cell was charged and discharged after being maintained in the chamber for 12 hours.

[0101] 2) The above-described voltage-reducing cell was charged in CC mode with a current of 0.1 C to a voltage of 0.01 V (vs. Li), and in CV mode from 0.01 V (vs. Li) to 0.005 C. After charging was complete, the cell was rested for 10 minutes, then discharged at 0.1 C to 1.5 V (vs. Li), and the charging and discharging process was repeated twice.

[0102] 3) Afterwards, it was charged with a current of 1.0 C until the voltage reached 0.01 V (vs. Li), rested for 10 minutes, and then discharged with a current of 1.0 C until the voltage reached 1.5 V (vs. Li).

[0103] 4) The charge and discharge cycles of process 3) above were performed up to a total of 50 times, and the capacity retention rate of the powder cell was measured. The results were presented as a graph in Fig. 4. (Capacity retention rate [%] = [n-th cycle capacity / 1-th cycle capacity])

[0105] (2) Evaluation results

[0106] Looking at the graph in Fig. 4, it was confirmed that for each cathode material (artificial graphite or core-shell particles), the compacted cells of 'Comparative Examples 1 and 2' containing a cathode active material without a coating portion exhibited the lowest capacity retention rate. On the other hand, it was confirmed that the compacted cells of 'Examples 1-2 and 2-2' containing only a LISICON-type oxide-based solid electrolyte in the coating portion showed an improved capacity retention rate compared to the compacted cells of 'Comparative Examples 1 and 2', and in the case of the compacted cells of 'Examples 1-1 and 2-1' containing both an oxide-based solid electrolyte and a binder in the coating portion, it was confirmed that they exhibited a superior capacity retention rate compared to the compacted cells of 'Examples 1-2 and 2-2'.

[0108] - Experimental Example 2: Evaluation of Electrochemical Impedance Spectroscopy (EIS) using a Powder Cell

[0109] (1) Evaluation method

[0110] 1) For the compressed cells of the embodiments according to Manufacturing Example 2 above, charging was carried out to a State of Charge (SOC) of 50% at 0.5 C.

[0111] 2) After the compaction cell is fully charged to 50%, set the frequency to 106 Hz ~ 0.05 Hz using EIS equipment, and then the Charge Transfer Resistance (R ct ) was measured, and the results are shown in Table 1 below.

[0113] Compressed cell Charge transfer resistance, R ct (Ω) Example 1-1 9.29 Examples 1-2 9.71 Examples 1-3 (Comparative Example 1) 11.13 Example 2-1 12.64 Example 2-2 12.9 Examples 2-3 (Comparative Example 2) 14.87

[0115] (2) Evaluation results

[0116] Looking at the results in Table 1 above, it was confirmed that for each cathode material (artificial graphite or core-shell particles), the compacted cells of 'Comparative Examples 1 and 2' containing a cathode active material without a coating part exhibited the highest charge transfer resistance. On the other hand, it was confirmed that the compacted cells of 'Examples 1-2 and 2-2' containing only a LISICON-type oxide-based solid electrolyte in the coating part showed a reduced charge transfer resistance compared to the compacted cells of 'Comparative Examples 1 and 2', and in the case of the compacted cells of 'Examples 1-1 and 2-1' containing both an oxide-based solid electrolyte and a binder in the coating part, it was confirmed that the charge transfer resistance was reduced even more than that of the compacted cells of 'Examples 1-2 and 2-2'. Based on the charge transfer resistance results described above, it was confirmed that the electrical conductivity between the interface of the cathode active material and the sulfide-based solid electrolyte can be improved by reducing the decomposition reaction between the cathode active material and the sulfide-based solid electrolyte through the introduction of the coating layer.

[0117] Therefore, through the results of Experimental Example 1 and Experimental Example 2 above, it was confirmed that an all-solid-state battery with excellent electrochemical properties can be manufactured by applying a coating portion containing an oxide-based solid electrolyte or further containing a binder to the negative electrode active material.

[0119] - Experimental Example 3: Measurement of BET specific surface area of ​​cathode active material

[0120] (1) Measurement method

[0121] For the negative electrode active material to which the coating portion was applied among the examples according to Manufacturing Example 1 above, the BET specific surface area of ​​the negative electrode active material in powder form was measured using nitrogen gas sorption, and the results are shown in Table 2 below.

[0123] cathode active material BET specific surface area (m²) 2 / g) Example 1-1 2.38 Examples 1-2 2.91 Example 2-1 2.77 Example 2-2 3.22

[0125] (2) Measurement results

[0126] Looking at the results in Table 2 above, it was confirmed that the specific surface area of ​​the negative electrode active materials of 'Examples 1-1 and 2-1', which contain both an oxide-based solid electrolyte and a binder in the coating portion, was reduced compared to the negative electrode active materials of 'Examples 1-2 and 2-2', which contain only an oxide-based solid electrolyte in the coating portion, respectively. Accordingly, it could be inferred that the negative electrode active material with a coating portion containing more binder has a further reduction in specific surface area compared to a coating portion containing only an oxide-based solid electrolyte, thereby further reducing physical contact with the sulfide-based solid electrolyte and more effectively suppressing the decomposition reaction of the sulfide-based solid electrolyte.

[0128] Although the embodiments have been described above with reference to limited drawings, those skilled in the art can apply various technical modifications and variations based on the above. For example, suitable results can be achieved even if the described techniques are performed in a different order than the described method, and / or the described components are combined or assembled in a form different from the described method, or are replaced or substituted by other components or equivalents.

[0129] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims set forth below. Explanation of the symbols

[0131] 100: Cathode active material 110: Cathode material 111: Core section 112: Shellbu 120: Coating part 200: Cathode current collector 300: Sulfide-based solid electrolyte 400: Lithium metal 500: Positive current collector 1: Lithium-ion battery

Claims

Claim 1 An anode active material comprising an anode material and a coating portion formed on the outer surface of the anode material, wherein the coating portion comprises an oxide-based solid electrolyte and the coating portion further comprises a binder, wherein the binder comprises one or more of PAA (Poly acrylic acid), PI (Polyimide), SBR (Styrene Butadiene Rubber), CMC (Carboxymethyl Cellulose), PVDF (Polyvinylidene fluoride), and PAN (Polyacrylonitrile). Claim 2 In claim 1, the oxide-based solid electrolyte comprises one or more of a LISICON (Lithium Super Ionic Conductor)-based compound, an LLZO (Lithium Lanthanum Zirconium Oxide)-based compound, an LLTO (Lithium Lanthanum Titanium Oxide)-based compound, a LATP (Lithium Aluminum Titanium Phosphate)-based compound, and a LiPON (Lithium Phosphorous Oxynitrides)-based compound, forming a negative electrode active material. Claim 3 In paragraph 2, the LISICON-based compound is Li (4-x) Si (1-x) P x O4, Li (4-x) Si (1-x) Al x O4, Li (4-x) Si (1-x) Ge x O4, Li (2+2x) Zn (1-x) GeO4 and Li (3+x) Ge x V (1-x) O4 (wherein for each compound, 0 <x<1)중 하나 이상을 포함하는,음극 활물질. Claim 4 In claim 1, the oxide-based solid electrolyte is a negative electrode active material comprising 1 to 10 weight percent relative to the total weight of the negative electrode active material. Claim 5 delete Claim 6 delete Claim 7 A negative electrode active material according to claim 1, wherein the weight ratio of the oxide-based solid electrolyte and the binder is 1:1 to 10:

1. Claim 8 In claim 1, the cathode material comprises one or more of a carbon-based cathode material and a metal-based cathode material, forming a cathode active material. Claim 9 In claim 8, the carbon-based cathode material comprises one or more of artificial graphite, natural graphite, MCMB (Mesocarbon microbead), hard carbon, soft carbon, graphene, reduced graphene oxide, carbon nanotube, carbon fiber, activated carbon, and carbon black, and the metal-based cathode material comprises one or more of a metal selected from the group consisting of Si, Ge, Sn, Mg, Al, Ca, Fe, Mn, Co, Ni, Zn, and Pb, an oxide of the metal, and an alloy of the metal, forming a cathode active material. Claim 10 In claim 1, the cathode material is a cathode active material having a core-shell structure. Claim 11 A cathode comprising a cathode active material, a conductive material, and a cathode binder according to any one of claims 1 to 4 and claims 7 to 10. Claim 12 A lithium-ion battery comprising a negative electrode, a negative current collector, an anode, a positive current collector, and a sulfide-based solid electrolyte according to claim 11. Claim 13 In Clause 12, the above-mentioned sulfide-based solid electrolyte is Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3PS4, Li 10 GeP2S 12 , Li7P3S 11 A lithium-ion battery comprising one or more of Li2S-P2S5, Li2S-SiS2, Li3PO4-P2S5, Li3PO4-Li2S-SiS2 and Thio-LISICON-based compounds.

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