Sustainable recycling of Li-ion battery electrodes requires molecularly-selective metal separations. This paper demonstrates a synergistic approach combining electrolyte control and interfacial design to achieve selective electrodeposition of cobalt and nickel, which have close reduction potentials. Concentrated chloride electrolyte leads to distinct speciation, forming an anionic cobalt chloride complex (CoCl₄²⁻) and a cationic nickel complex ([Ni(H₂O)₅Cl]+). Functionalizing electrodes with a positively charged polyelectrolyte (PDADMA) further tunes cobalt selectivity by modulating CoCl₄²⁻ mobility. This strategy, applied to commercially-sourced lithium nickel manganese cobalt oxide electrodes, yielded cobalt and nickel with purities of 96.4 ± 3.1% and 94.1 ± 2.3%, respectively. Technoeconomic analysis identifies electrolyte cost as a limiting factor, but suggests selective electrodeposition as an efficient battery recycling method.

Kwiyong Kim, Darien Raymond, Riccardo Candeago, Xiao Su