Reduction Roasting of Cathode Materials of NCM Based Lithium-ion Batteries Using CH4(g)

Jae-Ho Hwang; Sang-Yeop Lee; Ho-Sang Sohn

doi:10.7844/kirr.2025.34.4.48

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2025 Vol.34, Issue 4 Preview Page Next Page

Research Paper

Reduction Roasting of Cathode Materials of NCM Based Lithium-ion Batteries Using CH₄(g) NCM계 리튬이온 배터리 양극재의 CH₄(g)에 의한 환원 배소

31 August 2025. pp. 48-54

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Abstract

This study investigated the effect of temperature on the reduction roasting of NCM(LiNi_xCo_yMn_1-x-yO₂)-based cathode materials using methane(CH₄) to recover valuable metals from the spent lithium-ion batteries. Thermogravimetric analysis was conducted on NCM-based cathode materials in an Ar+50 vol.%CH₄(g) atmosphere ranging from room temperature to 1,100 °C. The sample weight was decreased from 750 °C, with the rapid generation of CO(g) at this temperature. In isothermal roasting, the final weight loss rate increased with increasing temperature. CO₂(g) was emitted before the CH₄(g) supply. CO(g) was emitted sharply at the same time as the CH₄(g) supply and reached a peak value, then decreased to a constant value with weight loss. The reduction of NiO was promoted with the increase of the roasting temperature. At temperature above 910 ℃, only Ni was present. This indicates that most of the oxides had been reduced to metals. The Li recovery rate increased with the roasting temperature increased. The Li compounds recovered from the leachate were identified as Li₂CO₃, LiOH and LiOH·H₂O. Therefore, it is thought that hydrogen reduction by the decomposition of CH₄(g) also occurred. It is also thought that Li compounds and metals such as Ni and Co can be separated and recovered by reduction roasting the NCM powder using CH₄(g) at temperatures above 900 ℃, followed by water leaching.

Keywords

lithium-ion battery

methane

reduction roasting

lithium carbonate

lithium hydroxide

본 연구에서는 폐리튬이온배터리에서 유가금속 회수를 위해 CH₄(g)에 의한 NCM(LiNi_xCo_yMn_1-x-yO₂)계 양극재의 환원 배소에 미치는 온도의 영향에 관하여 조사하였다. NCM계 양극재 시료를 Ar+50 vol.%CH₄(g) 분위기에서 1,100 ℃까지 열중량 분석한 결과 약 750 ℃부터 시료의 무게가 감소하는 경향을 나타내었으며, 이때 CO(g)가 급격하게 발생하였다. 등온 배소에서는 온도가 높을수록 최종 무게 감소율이 증가하였으며, CO₂(g)는 CH₄(g) 공급 전에 발생하였다. 배가스 중 CO(g)는 CH₄(g) 공급과 동시에 급격하게 발생하여 최곳값을 보인 후 감소하여 무게 감소와 함께 일정한 값을 나타낸 후 다시 감소하였다. 배소 온도 상승과 함께 NiO의 환원이 촉진되고, 910 ℃ 이상에서는 Ni만 관찰되어 대부분의 산화물이 환원되었다. 배소 온도의 상승과 함께 Li 회수율이 증가하였으며, 침출 여액에서 회수한 Li 화합물은 Li₂CO₃, LiOH, LiOH·H₂O로 검출되었다. 따라서 CH₄(g)의 분해에 의해 수소에 의한 환원도 일어난 것으로 생각되며, NCM 분말을 약 900 ℃ 이상에서 CH₄(g)로 환원 배소한 후 수침출하면 Li 화합물과 Ni, Co 등의 금속을 분리·회수할 수 있는 것으로 생각된다.

키워드

리튬이온배터리

메테인

환원배소

탄산리튬

수산화리튬

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Information

Publisher :The Korean Institute of Resources Recycling
Publisher(Ko) :한국자원리싸이클링학회
Journal Title :Resources Recycling
Journal Title(Ko) :자원리싸이클링
Volume : 34
No :4
Pages :48-54
Received Date : 2025-07-21
Revised Date : 2025-08-12
Accepted Date : 2025-08-14
DOI :https://doi.org/10.7844/kirr.2025.34.4.48

Resources Recycling ISSN:2765-3439(Print) 2765-3447(Online) 자원리싸이클링

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