Potassium Doping Facilitated Formation of Tunable Superoxides in Li 2 O 2 for Improved Electrochemical Kinetics.

Superoxide (O) species play a crucial role in determining the charge kinetics for aprotic lithium-oxygen (Li-O) batteries. However, the growth of O-rich lithium peroxide (LiO) is challenging since O is thermodynamically unfavorable and unstable in an O atmosphere. Herein, we reported the synthesis of defective LiO with tunable O via K doping. The K dopants can successfully stabilize O species and induce the coordination of Li with O, leading to increased Li vacancies. Compared to the pristine LiO, the as-prepared defective LiO can be charged at a lower overpotential in Li-O batteries, which is ascribed to further increased Li vacancies contributed by the depotassiation process at the onset of the charge process. Our findings suggest a new strategy to better control O species in LiO by K dopants and provide insights into the K effects on charge mechanism in Li-O batteries.