Method for recycling cathode materials from spent lithium-ion batteries

High-temperature roasting-based cathode leaching process using low-grade graphite from spent anodes as a reducing agent

This technology improves leaching efficiency by performing a roasting process before leaching, using low-grade graphite separated from spent lithium-ion battery anodes as a reducing agent to convert cathode metal oxides, such as cobalt and nickel, into their metallic states.

In conventional hydrometallurgical leaching, cathode materials exist as metal oxides, resulting in slow dissolution rates in sulfuric acid and low leaching efficiency. This necessitates the use of additional external reducing agents.

This technology involves mixing low-grade graphite recovered from spent batteries with cathode materials and roasting the mixture in an oxygen-free atmosphere at 1030–1090°C to reduce metal oxides to pure metals before acid leaching. Applicable to hydrometallurgical recycling plants or cobalt/nickel recovery lines, it reduces costs by eliminating the need for external reducing agents and repurposes waste graphite as a process resource.

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Key Features:

• A cathode separation step where spent lithium-ion batteries are dismantled to isolate the cathode materials composed of metal oxides
• A mixing step where low-grade graphite from anode refining is added to the cathode material at an equivalent ratio of 2–3 times the target metal
• A roasting step where the carbon-mixed cathode material is heated at 1030–1090°C to reduce cobalt and nickel
• A leaching step where the roasted cathode material is placed in an acid solution to extract the metals and form a metal leachate

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of advanced hydrometallurgical technologies to increase the value of recovered resources.

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