Compulsive malposition of birnessite slab in 2D-Parallel birnessite on β-MnO2 networks for enhanced pseudocapacitance performances

High electrochemically active birnessite is always desirable pseudocapacitive material for supercapacitor. Here, two-dimensional (2D) compulsive malposition parallel birnessite standing on β-MnO2 interconnected networks have been designed. Due to the restriction of β-MnO2, compulsive malposition, slippage of MnO6 slab, occurred in birnessite resulting in weaken binding force between birnessite slab and interlayer cations, which enhanced their electrochemical performances. Additionally, the electrical conductivity of the structure was largely promoted by the 2D charge transfer route and double-exchange mechanism in birnessite, also leading to desirable electrochemical properties. Based on the fraction of as-prepared nanostructure, the parallel birnessite exhibited good pseudocapacitance performance (660 ​F ​g−1) with high rate capability. In addition, the asymmetric supercapacitor assembled by reduced graphene oxide (RGO) and as-prepared nanostructure, which respectively served as the negative and positive electrode, delivered an energy density of 33.1 ​Wh kg−1 and a maximum power density of 64.0 ​kW ​kg−1 with excellent cycling stability (95.8% after 10000 cycles). Finally, the study opens new avenues for synthesizing high electrochemically active birnessite structure for high-performance energy storage devices.