Reduction Behavior of Black Mass Recovered from NCM-Based Spent Lithium-ion Batteries in Ar Atmosphere

초록

With the growing demand for LIBs (lithium-ion batteries) for EVs (electric-powered vehicles), it willbe important to recover valuable metals from spent lithium-ion batteries in the future. The black massrecovered from spent lithium-ion battery contains elements such as Li, Ni, Co, and Mn with C. The carbonin the black mass can act as a reducing agent of oxide. This study investigated the effect of reactiontemperature on the reduction behavior and Li recovery from black mass powder mixed with spent NCM(LiNixCoyMnzO2) powder and C in an Ar atmosphere. In the isothermal reaction, the weight loss rate increasedwith an increase of temperature, and the final amount of weight loss also increased. After significant weightloss, the NCM powder was decomposed and nickel and cobalt oxides were reduced to metals. When significantweight loss occurred, a significant amount of CO gas was also emitted. This phenomenon is due to thereduction of nickel and cobalt oxides in the black mass and the reaction of CO2 with C by the Boudouardreaction. When the isothermally reacted black mass was leached in water, the Li recovery increased with anincrease of the reaction temperature, and the Li recovery above 900 °C was about 98%. From these results,by heating the black mass in an inert atmosphere lithium can be separated and recovered from valuablemetals and C.

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