KR-20260062202-A - COATING METHOD OF POSITIVE ELECTRODE ACTIVE MATERIAL FOR ALL SOLID STATE SECONDARY BATTERY AND POSITIVE ELECTRODE AND ALL SOLID STATE SECONDARY BATTERY USING THE SAME

Abstract

A method for coating a positive electrode active material for an all-solid-state secondary battery using a metal sulfide is disclosed, and a positive electrode having a metal sulfide coating layer lithiated through a discharge process using the same and an all-solid-state secondary battery are disclosed. A method for coating a positive electrode active material according to the present invention comprises: (a) a step of dissolving a metal sulfide precursor in a polar solvent and then adding a positive electrode active material; and (b) a step of heat-treating the solution containing the positive electrode active material to form a metal sulfide coating layer on the surface of the positive electrode active material; wherein the metal sulfide coating layer comprises MoS₃ .

Inventors

• 조우석
• 유지상
• 김경수
• 최승호
• 정재엽

Assignees

• 한국전자기술연구원

Dates

Publication Date

20260507

Application Date

20241025

Claims (11)

1. (a) a step of dissolving a metal sulfide precursor in a polar solvent and then adding an anode active material; and (b) a step of heat-treating the solution to which the above positive active material has been added to form a metal sulfide coating layer on the surface of the positive active material; comprising, The above metal sulfide coating layer is a method for coating an anode active material containing MoS₃ .
2. In paragraph 1, A method for coating a positive electrode active material by adding 0.1 to 2 weight percent of a metal sulfide precursor to 100 weight percent of the total positive electrode active material and metal sulfide precursor in step (a) above.
3. In paragraph 1, A method for coating an anode active material in which the heat treatment in step (b) above is performed at 100 to 300°C for 30 minutes to 10 hours.
4. In paragraph 1, A method for coating a positive electrode active material comprising one or more lithium transition metal oxides among lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium iron phosphate oxide.
5. In paragraph 1, A method for coating an anode active material, wherein the above polar solvent comprises one or more of acetone, ethanol, methanol, dimethyl sulfoxide (DMSO), pyridine, acetic acid, hexamethylinsporamide (HMPA), and dimethylformamide (DMF).
6. The whole house; and A positive material disposed on at least one surface of the above-mentioned current collector; comprising The above-mentioned cathode material is The positive active material having a metal sulfide coating layer formed on its surface, the first solid electrolyte, and the carbon-based conductive material are included. The above metal sulfide coating layer Anode comprising Li- MoS₃ formed by discharging up to 1.4V.
7. In paragraph 6, An anode comprising 0.1 to 2 weight percent of metal sulfide based on 100 weight percent of the total anode active material and metal sulfide.
8. In paragraph 6, The above first solid electrolyte is an anode comprising a sulfide-based solid electrolyte.
9. In paragraph 8, The above first solid electrolyte is an anode comprising one or more of Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x (0≤x≤2).
10. In paragraph 6, A method for coating a positive electrode active material comprising one or more lithium transition metal oxides among lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium iron phosphate oxide.
11. Anode according to Paragraph 6; cathode; and All-solid-state secondary battery comprising a second solid electrolyte.

Description

Coating method of positive electrode active material for all solid state secondary battery and positive electrode and all solid state secondary battery using the same The present invention relates to a method for coating a positive electrode active material for an all-solid-state secondary battery using a metal sulfide, and to a positive electrode having a metal sulfide coating layer lithiated through a discharge process using the same, and an all-solid-state secondary battery. Sulfide-based all-solid-state batteries are batteries that use solid-state materials as electrolytes, and are considered a representative next-generation secondary battery system due to their expected high energy density and excellent safety. In sulfide-based all-solid-state batteries, the positive electrode consists of an oxide-based positive active material, a sulfide-based solid electrolyte, and a carbon-based conductive material, and the design of their ratios is important. In addition, uniform dispersion and contact between electrode materials form pathways for lithium ion and electron transport, which has a significant impact on battery performance. Therefore, technology to improve the contact area between the positive electrode active material and the solid electrolyte is required, and at the same time, the problem of interfacial side reactions occurring during the charge-discharge process must be resolved. Generally, the structure of the positive electrode active material deteriorates through physical contact with the sulfide-based solid electrolyte, and the solid electrolyte also undergoes electrochemical decomposition, leading to performance degradation. To solve conventional problems, coating technology is required that can increase the transport area of lithium ions at the interface between the anode and the solid electrolyte and improve the electrochemical stability of the interface. High-strength oxide-based materials ( LiNbO3 , LiAlO2 , LiTaO3 , etc.) have mainly been used as coating materials for cathode active materials. However, these materials generally have very low lithium ion mobility. In addition, there is a disadvantage of increased cost in that a coating and sintering temperature of 500°C or higher is required in the step of forming a coating layer containing the oxide-based material. Figure 1 is a schematic diagram of the improvement in the contact ratio with a solid electrolyte through the formation of a coating layer of a positive electrode active material according to the present invention. Figure 2 is the synthesis result of MoS3 , a coating material for the positive electrode active material according to the present invention. Figure 3 is an SEM-EDS image of a 1 wt% MoS3 -coated positive electrode active material according to the present invention. Figure 4 is the result of X-ray Photoelectron Spectroscopy (XPS) analysis of a 1 wt% MoS3 coated positive electrode active material according to the present invention. Figure 5 is the battery evaluation result of an all-solid-state secondary battery to which a positive electrode active material coated with MoS3 according to the present invention is applied. Figure 6 is a discharge graph up to 1.4V of an all-solid-state secondary battery according to the present invention. Figure 7 is a cycle graph of an all-solid-state secondary battery using general NCM. FIG. 8 is a cycle graph of an all-solid-state secondary battery with 1 wt% MoS3 coated NCM according to the present invention. Figure 9 is a cycle graph of an all-solid-state secondary battery using 1 wt% MoS3 coated NCM that underwent lithiumization before charging and discharging. The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components. In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component. In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "int