Fabrication of hierarchical MoO₃–PPy core–shell nanobelts and “worm-like” MWNTs–MnO₂ core–shell materials for high-performance asymmetric supercapacitor

Asymmetric supercapacitors (ASCs) are successfully developed with configuration of negative electrode using hierarchical MoO₃–PPy core–shell nanobelts (MoO₃–PPy) and positive electrode with “worm-like” MWNTs–MnO₂ core–shell materials (CNTs–MnO₂) in Na₂SO₄ aqueous electrolyte. The MoO₃ nanobelts are prepared by a facile hydrothermal method and get significant improvement in specific capacitance with modification of PPy layer from 124 to 285 F/g. Furthermore, the optimized ASCs based on the MoO₃–PPy//CNTs–MnO₂ can achieve 1.8 V high voltage even in Na₂SO₄ aqueous solution and possess a high energy density of 21.03 Wh/kg at the power density of 0.22 kW/kg. Additionally, the ASCs exhibit excellent cycle stability, with 76% retention of its original value even after 10000 cycles. The ASCs are further demonstrated to light up a red light-emitting diode in series. These encouraging results indicate a promising application in the energy-storage devices with high power density and energy density.