KNi_0.8Co_0.2F₃ as an Efficient Electrocatalyst for Nonaqueous Li–O₂ Batteries

The rechargeable nonaqueous Li–O2 battery provides an ultrahigh theoretical energy density for energy storage application. However, its electrochemical performance is significantly hindered by numerous challenges including short cycle life, lower round-trip efficiency, and insulation caused by lithium peroxide (Li2O2) that results in a large overpotential. Utilizing known merits of fluoride perovskite structures and building on previous studies in an aqueous electrolyte, KNi0.8Co0.2F3 (KNCF82), shows promise as a Li–O2 battery electrocatalyst. When placed in a nonaqueous rechargeable Li–O2 battery, the KNCF82 cathode demonstrates an improved specific capacity of ∼9600 mA h g–1 at a current density of 175 mA g–1. The battery shows a cycling stability for 85 cycles with a narrow charge–discharge voltage difference of 1.41 V when the capacity was regulated at 500 mA g–1 and a round-trip efficiency of 63%. Further, despite a slight increase in overpotential, the cell exhibited good stability for 145 cycles and cycled over 835 h.