NCM계 리튬이온 배터리 양극재의 CH4(g)에 의한 환원 배소

초록

This study investigated the effect of temperature on the reduction roasting of NCM(LiNixCoyMn1-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.

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