Perovskite fluoride KMF3 (M = Ni or Co)@reduced graphene oxide anode for Na-based dual-ion batteries

Abstract Because of its low cost and high energy density, Na-based dual-ion batteries (Na-DIBs) have attracted more and more research and technical attention, providing broad prospects for emerging energy storage and conversion applications. However, developing advanced anodes for Na-DIBs with high energy density, long cycle life and high power density remains challenging. Here we demonstrate a facile strategy to synthesize KMF3 (M = Ni or Co)@reduced graphene oxide (recorded as KMF3 (M = Ni or Co)@rGO or Ni-G and Co-G) by a one-pot method. The Ni-G and Co-G electrodes exhibit a pseudocapacitive kinetics and a typical highly reversible conversion reaction mechanism by cyclic voltammetry (CV) and ex situ X-ray photoelectron spectroscopy (XPS). Further assembled with KS6 to form Na-DIBs, Ni-G//KS6 and Co-G//KS6 deliver high energy density (328.8 Wh kg-1 and 187.6 Wh kg-1), high power density (18.29 kW kg-1 and 21.62 kW kg-1) and cycle life over 1000 cycles. Moreover, these devices work well at -20-40 °C. This work discusses new insights into perovskite fluoride as Na-DIBs, providing a strategy for high-energy-density and long-cycle energy storage systems.