Hydrogen-Treated Spent Lithium Cobalt Oxide as an Efficient Electrocatalyst for Oxygen Evolution

The extensive use of lithium-ion batteries (LIBs) has caused environmental pollution and waste of resources. Developing sustainable recycling strategies for the cathode of spent LIBs can bring about resource conservation and environmental benefits. In this work, the in situ reconstruction and functional reuse of spent LiCoO2 were realized through two steps of chemical delithiation and hydrogen treatment. The chemical delithiation promotes spent LiCoO2 to form a 3D layered structure, exposing more active sites and increasing charge transfer. Thermal treatment of hydrogen induces LiCoO2 transition to a lower valence state and forms more oxygen vacancies, which are more beneficial to the oxygen evolution reaction. Consequently, the Ar-H2-300 °C-delithiation from spent lithium cobalt oxide (DLSLCO) exhibits high catalytic oxygen evolution reaction (OER) performance with a low overpotential of 365 mV at 10 mA cm–2 and a small Tafel slope of 67 mV decade–1, which is even comparable to that of the recovered or synthesized LiCoO2 catalysts reported in other literature studies.