Vertically\nAligned Ultrathin CoNi-LDH@NiS@MXCF Core–Shell\nHeterostructure for Flexible Supercapacitor Electrodes and Oxygen\nEvolution Reaction

A multilayer\ncore–shell heterostructure with CoNi-LDH\nas\nthe core and NiS nanosheets as the shell is deposited on MXene-coated\ncarbon nanofibers by electrospinning and electrochemical deposition.\nThis unique structure not only combines highly conductive and hydrophilic\none-dimensional carbon nanofibers but also exposes abundant two-dimensional\nreactive sites and multiple ion diffusion channels to maximize material\nutilization, enhance electron transfer kinetics, accelerate Faraday\nreaction, high capacitance and strong stability. The CNNS@MXCF electrode\nexhibits outstanding electrochemical characteristics, including a\ncapacity of 1441.8 F g<sup>–1</sup> at a current density of\n1 A g<sup>–1</sup> and excellent cycling stability. The CNNS@MXCF//VN@MXCF\ndevice shows a high energy density of 84.4 Wh kg<sup>–1</sup> at 0.8 kW kg<sup>–1</sup> power density, with nearly 92%\ncapacitance retention after 10,000 cycles (30 A g<sup>–1</sup>). In addition, the oxygen evolution reaction (OER) shows a small\noverpotential of 128 mV, confirming the versatility and large potential\nof the materials and strategy.