Efficient metal recovery and electrocatalyst fabrication from spent lithium-ion batteries via green solvent extraction

Abstract

The accelerated production of lithium-ion batteries (LIBs) causes the decommissioning tide of spent LIBs. Therefore, developing a sustainable battery recycling strategy can minimize environmental pollution and save valuable resources. We present an easy and innovative method to transform spent LiNi_1−x−yCo_xMn_yO₂ (NCM) cathodes into nickel cobalt sulfide (NCS) electrocatalysts for the oxygen evolution reaction (OER). This process involves separating metal ions using green and reusable deep eutectic solvents (DESs), which play multiple roles of a leaching agent, metal source and template, simplifying the multi-stage metal separation process and reducing contamination and waste. Then, NCS clings to carbon fiber paper (CFP) using thioacetamide. The prepared NCS electrode presents a hollow nanorod array structure with rich active sites and high surface hydrophilicity, which can be engineered by adjusting the heating conditions via the Ostwald ripening mechanism. The NCS electrode exhibits satisfactory OER performance, featuring a modest overpotential (η₁₀ = 248 mV at 10 mA cm⁻²), small charge-transfer resistance (2.4 Ω), a Tafel slope of 67.74 mV dec⁻¹, and stable operation for 125 hours. The new recovery technology in this work presents an instructive and feasible approach for recycling spent LIBs into multimetallic sulfide OER electrocatalyst materials.