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.