Binder-free MnO2 as a high rate capability cathode for aqueous magnesium ion battery

Abstract Manganese dioxide (MnO2) is considered as a potential cathode material for aqueous magnesium-ion batteries (MIBs) owing to the high theoretical capacity of 308 mAh g−1, low cost and high abundance. However, the essentially poor electrical conductivity of MnO2 leads to low rate performance and short lifespan in the dated MnO2 electrodes prepared by the traditional slurry coating route. In present study, the binder-free e-MnO2 nanoflakes as a robust cathode for aqueous MIBs is reported. This method provides the direct contact of e-MnO2 with the current collector, and thus remarkably improves the electrical conductivity. The binder-free e-MnO2 delivers a high specific capacity of 259.3 mAh g‒1 at 0.5 A g‒1, excellent rate capability, and a long cycling stability of 94.3% retention after 400 cycles. Further, a full cell MIB incorporated with the e-MnO2 cathode delivers high rate capability and high energy density of 98.6 Wh kg‒1.