High-performance flexible asymmetric supercapacitor based on hierarchical MnO/PPy nanocomposites covered MnOOH nanowire arrays cathode and 3D network-like FeO/PPy hybrid nanosheets anode.

The configuration of asymmetric supercapacitors (ASCs) has proven to be an effective approach to increase the energy storage properties due to the expanded working voltage resulting from the well-separated potential windows of the cathode and anode. However, carbonaceous anode materials generally suffer from relatively low capacitance, which restricts the enhancement of the energy storage performance of the full device in a traditional asymmetrical design. Herein, a rational design of all-pseudocapacitive ASCs (APASCs) using pseudocapacitive materials with a novel hierarchical nanostructure on both electrodes was developed to optimize the electrochemical properties for high-performance ASC devices. The assembled APASC employed the MnO/PPy nanocomposites covered MnOOH nanowire arrays with core-shell hierarchical architecture as the cathode and FeO/PPy hybrid nanosheets with 3D porous network-like structure as the anode. Owing to the coordinated pseudocapacitive properties and unique hierarchical nanostructures, this assembled APASC exhibited an exceptional volumetric capacitance of 4.92F cm in a stable voltage window of 2 V, a maximum volumetric energy density of 2.66 mWh cm at 19.72 mW cm, and excellent cyclic stability over 10,000 cycles (90.6 % capacitance retention), as well as remarkable flexibility and mechanical stability, providing insights for the design of flexible energy storage systems with enhanced performance.