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

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.