Improving the Rechargeable Li-CO Battery Performances by Tailoring Oxygen Defects on Li-Ni-Co-Mn Multi-Metal Oxide Catalysts Recycled from Spent Ternary Lithium-Ion Batteries.

Rechargeable Li-CO batteries are considered as a promising carbon-neutral energy storage technology owing to their ultra-high energy density and efficient CO capture capability. However, the sluggish CO reduction/evolution kinetics impedes their practical application, which leads to huge overpotentials and poor cyclability. Multi-element transit metal oxides (TMOs) are demonstrated as effective cathodic catalysts for Li-CO batteries. But there are no reports on the integration of defect engineering on multi-element TMOs. Herein, the oxygen vacancy-bearing Li-Ni-Co-Mn multi-oxide (Re-NCM-H3) catalyst with the α-NaFeO-type structure is first fabricated by annealing the NiCoMn precursor that derived from spent ternary LiNiCoMnO cathode, in H at 300 °C. As demonstrated by experimental results and theory calculations, the introduction of moderate oxygen vacancy has optimized electronic state near the Fermi level (E), eventually improving CO adsorption and charge transfer. Therefore, the Li-CO batteries with Re-NCM-H3 catalyst deliver a high capacity (11808.9 mAh g), a lower overpotential (1.54 V), as well as excellent stability over 216 cycles at 100 mA g and 165 cycles at 400 mA g. This study not only opens up a sustainable application of spent ternary cathode, but also validates the potential of multi-element TMO catalysts with oxygen defects for high-efficiency Li-CO batteries.