Recycling and regenerating of spent ternary cathode in lithium-ion battery via the corn straw-induced thermal reduction.

To address the problems in the conventional carbothermal-reduction methods for recovery of the spent ternary cathodes in lithium-ion batteries (LIBs), particularly the low-utilization and high-value reductants, this study introduces an optimized thermal-reduction technique utilizing agricultural waste of corn straw as a reductant. The pyrolysis of corn straw generates highly reductive species of C, H, CH, and CO, which converts the reaction mechanism from a conventional solid-solid reaction to a combined solid-solid/solid-gas reactions. This significantly enhances the reduction efficiency of LiNiCoMnO (LNCMO), enabling the reduction of high-value metals into Ni, Co, and MnO, while converting Li into LiCO. Notably, the optimal corn straw-induced thermal-reduction temperature is 700 °C with the high-utilization efficiency of corn straw. Under the optimal conditions, Li can achieve a high recovery rate of 95.8 %, which exceeds that of the conventional carbothermal reduction techniques. Additionally, the reduction products can be successfully regenerated into LiNiCoMnO. The discharge specific capacity and coulombic efficiency of the regenerated LiNiCoMnO is 163.9 mA h g and 94.6 %, respectively. This study provides a novel strategy for the utilization of agricultural waste to achieve high-efficiency recovery of the ternary cathode materials from spent LIBs.