Carbon alternative pseudocapacitive V2O5 nanobricks and δ-MnO2 nanoflakes @ α‐MnO2 nanowires hetero-phase for high-energy pseudocapacitor

Abstract

The limited energy density of the carbon-based asymmetric supercapacitor forces us to find carbon alternative electrode materials to simultaneous boost the energy and power density for supercapacitor cell. The pseudocapacitive materials hold great promise to provide a high energy at high charge-discharge rate. In present work, we have engineered the pseudocapacitive δ‐MnO2 Nanoflakes @ α-MnO2 Nanowires (δ‐MnO2 NFs@ α-MnO2 NWs) hetero-phase core-shell and V2O5 Nanobricks (NBs) on flexible carbon cloth for all-pseudocapacitive asymmetric supercapacitor. The resulting pseudocapacitive δ‐MnO2 NFs@ α-MnO2 NWs and V2O5 NBs reveal excellent electrochemical features in positive and negative potential with the capacitance of 310 F g−1 (0.06 F cm−2) and 167 F g−1 (0.029 F cm−2), respectively. With advantages of positive and negative potentials of δ‐MnO2 NFs@ α-MnO2 NWs and V2O5 NBs electrodes, all-pseudocapacitive asymmetric supercapacitor are assembled and stably operated in 1.5 V exhibits a specific capacitance of 204 F g−1 (12.2 F cm−3). The fabricated supercapacitor cell exhibits high specific energy of 63 Wh kg−1 at 2600 W kg−1 (3.82 Wh cm−3 at 15.8 W cm−3) with smaller relaxation time constant of 0.78 s, and showed remarkably excellent cyclic stability with ~100% and ~95% columbic efficiency of the original performance over 5000 cycles. In addition, these types of materials provide a major incentive for large-scale and high-performance energy storage devices.