Flexible Hybrid Membranes of NiCo2O4-Doped Carbon Nanofiber@MnO2 Core–Sheath Nanostructures for High-Performance Supercapacitors

Construction of MnO2-based hybrid nanostructures with carbonaceous materials has been considered as one of the most efficient strategies to overcome excessive aggregations of MnO2 particles. Here, a facile approach of growing δ-phase and γ-phase MnO2 with distinctly different morphologies on highly conductive NiCo2O4-doped carbon nanofibers (NCCNFs) through the combination of electrospinning, solution codeposition, and redox deposition methods is presented to form NCCNF@MnO2 nanosheet (or nanorod) core–sheath nanostructures. The obtained two kinds of flexible hybrid membranes with hierarchical nanostructures are both evaluated as electrodes for high-performance supercapacitors. The greatly improved specific surface areas for ionic adsorption, significantly enhanced conductivity of NCCNF, and an open three-dimensional network for rapid electron transportation during the electrochemical processes jointly lead to remarkably enhanced specific capacitances of 918 and 827 F g–1 (based on the active materials) at a scan rate of 2 mV s–1 and good cycling ability with 83.3% and 87.6% retention after 2000 cycles for NCCNF@MnO2 nanosheet and NCCNF@MnO2 nanorod hybrid membranes, respectively. Therefore, this work suggests a novel strategy for design and potential application of MnO2 hybrid materials in high-performance supercapacitors.