Carbon alternative pseudocapacitive V_2O_5 nanobricks and δ-MnO_2 nanoflakes @ α-MnO_2 nanowires hetero-phase for high-energy pseudocapacitor

摘要

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 delta-MnO2 Nanoflakes @ alpha-MnO(2 )Nanowires (delta-MnO2 NEs@ alpha-MnO2 NWs) hetero-phase core-shell and V2O5 Nanobricks (NBs) on flexible carbon cloth for all-pseudocapacitive asymmetric supercapacitor. The resulting pseudocapacitive delta-MnO2 NEs@ alpha-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 delta-MnO2 NEs@ alpha-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 similar to 100% and similar to 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.