Recycling spent LiNi1-x-yMnxCoyO2 cathodes to bifunctional NiMnCo catalysts for zinc-air batteries

Abstract

The skyrocketing production of lithium-ion batteries (LIBs) for electric vehicles portends that tremendous numbers of used LIBs will be generated. However, the recycling of used LIBs is limited by the complicated separation processes of traditional pyrometallurgy and hydrometallurgy methods. Here, we applied a rapid thermal radiation method to convert spent LiNi1-x-yMnxCoyO2 (NMC) cathodes from used LIBs into highly efficient NiMnCo-based catalysts for zinc-air batteries (ZABs) through acid leaching and radiative heating processes, which avoids sophisticated separation of different metals and can synthesize the catalysts rapidly. The prepared NiMnCo-activated carbon (NiMnCo-AC) catalyst presents a unique core-shell structure, with face-centered cubic Ni in the core and spinel NiMnCoO4 in the shell, which redistributes the electronic structure of the NiMnCoO4 shell to decrease the energy barrier for oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) processes and ensures high electrocatalytic activities. The NiMnCo-AC catalyst in ZABs as cathode materials exhibits a high power density of 187.7 mW cm22, low voltage gap of 0.72 V at the initial three cycles, and long cycling duration of 200 h at the current density of 10 mA cm22. This work provides a promising strategy to recycle spent LIBs to highly efficient catalysts for ZABs.