Vertically Aligned Ultrathin CoNi-LDH@NiS@MXCF Core–Shell Heterostructure for Flexible Supercapacitor Electrodes and Oxygen Evolution Reaction

A multilayer core-shell heterostructure with CoNi-LDH as the core and NiS nanosheets as the shell is deposited on MXene-coated carbon nanofibers by electrospinning and electrochemical deposition. This unique structure not only combines highly conductive and hydrophilic one-dimensional carbon nanofibers but also exposes abundant two-dimensional reactive sites and multiple ion diffusion channels to maximize material utilization, enhance electron transfer kinetics, accelerate Faraday reaction, high capacitance and strong stability. The CNNS@MXCF electrode exhibits outstanding electrochemical characteristics, including a capacity of 1441.8 F g^-1 at a current density of 1 A g^-1 and excellent cycling stability. The CNNS@MXCF//VN@MXCF device shows a high energy density of 84.4 Wh kg^-1 at 0.8 kW kg^-1 power density, with nearly 92% capacitance retention after 10,000 cycles (30 A g^-1). In addition, the oxygen evolution reaction (OER) shows a small overpotential of 128 mV, confirming the versatility and large potential of the materials and strategy.