We upcycle spent lithium-ion battery (LIB) electrodes into CoMoS₄, an efficient bifunctional electrocatalyst for water splitting. This cost-effective and sustainable approach involves carbothermic reduction of LiCoO₂ (LCO) with graphite, both recovered from used batteries, followed by a simple hydrothermal reaction.

Abstract

Upcycling spent lithium-ion battery (LIB) electrode material, namely LiCoO₂ (LCO), as an efficient electrocatalyst for water splitting is an attractive strategy toward sustainable energy solutions. While some of the efforts have demonstrated promising results in this direction, there are still challenges to be addressed for the industrial-scale processing of the materials. In this work, we demonstrate an acid-free, eco-friendly, and cost-effective approach of upcycling LCO to cobalt molybdenum sulfide, an efficient electrocatalyst for overall water splitting, through a simple hydrothermal method. As-synthesized CoMoS₄ on nickel foam (CMS-NF) shows very good bifunctional activity for alkaline water splitting with a low overpotential for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 M KOH. A full cell is fabricated with CoMoS₄ as both the cathode and anode (CMS-NF//CMS-NF) toward overall water splitting, which exhibits a voltage of 1.60 V to achieve a current density of 10 mA cm⁻² with good stability over 60 h. Our strategy effectively addresses the issues associated with battery waste management and gives impetus to sustainable green energy.