LAUSR

Rechargeable Li‐CO2 batteries are considered as a promising carbon‐neutral energy storage technology owing to their ultra‐high energy density and efficient CO2 capture capability. However, the sluggish CO2 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‐CO2 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‐NaFeO2‐type structure is first fabricated by annealing the NiCoMn precursor that derived from spent ternary LiNi0.8Co0.1Mn0.1O2 cathode, in H2 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 (Ef), eventually improving CO2 adsorption and charge transfer. Therefore, the Li‐CO2 batteries with Re‐NCM‐H3 catalyst deliver a high capacity (11808.9 mAh g−1), a lower overpotential (1.54 V), as well as excellent stability over 216 cycles at 100 mA g−1 and 165 cycles at 400 mA g−1. 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‐CO2 batteries.