Membrane-less MoO3−x@TiO2-bromine battery with excellent rate capability and cyclic stability

Abstract

Bromine has attracted significant attention as a cathode material for aqueous batteries due to its high reduction potential of 1.05 V (Br3− + 2e− ↔ 3Br−), impressive theoretical specific capacity of 223 mA h g−1, and rapid reaction kinetics in the electrolyte. However, searching for compatible anode materials to match with bromine has posed a challenge due to its highly corrosive nature. In this study, we developed oxygen-deficient MoO3 with TiO2 coating (referred to as MoO3−x@TiO2) as an anode material to pair with a bromine cathode in static full batteries. The oxygen deficiency contributes to enhanced electronic and protonic diffusion within the MoO3−x lattice, while the TiO2 coating mitigates structural dissolution and proton trapping during cycling. The MoO3−x@TiO2 demonstrates fast charge storage kinetics and excellent resistance to bromine corrosion. The impressive compatibility between MoO3−x@TiO2 and bromine enables the construction of membrane-less full batteries with exceptional rate capability and cyclic stability. The MoO3−x@TiO2-bromine battery achieves an energy density of 70.8 W h kg−1 at a power density of 328.1 W kg−1, showcasing an impressive long-term cyclic life of 20,000 cycles. Our study provides valuable insights for the development of high-performance aqueous secondary batteries.