Improving the Rechargeable Li‐CO2 Battery Performances by Tailoring Oxygen Defects on Li‐Ni‐Co‐Mn Multi‐Metal Oxide Catalysts Recycled from Spent Ternary Lithium‐Ion Batteries

Abstract Rechargeable Li‐CO 2 batteries are considered as a promising carbon‐neutral energy storage technology owing to their ultra‐high energy density and efficient CO 2 capture capability. However, the sluggish CO 2 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 2 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 2 ‐type structure is first fabricated by annealing the NiCoMn precursor that derived from spent ternary LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode, in H 2 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 f ), eventually improving CO 2 adsorption and charge transfer. Therefore, the Li‐CO 2 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‐CO 2 batteries.