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Transition metal nitrides (TMNs) are promising electrode materials for high-performance energy storage devices owing to their excellent conductivity, thermal stability, high theoretical capacity and excellent electrochemical activity. However, the structural instability present in the electrochemical reaction process significantly limits their widespread application. Herein, we present a V–Ni-based nitride heterojunction on carbon cloth (VN/Ni3N–Ni/CC) as an active electrode material for flexible supercapacitors. The VN/Ni3N–Ni/CC composite electrode was successfully fabricated through controllable nitridation of the corresponding vanadium–nickel oxide grown on carbon cloth (V–Ni–O/CC) precursors. The electrochemical results reveal that the areal capacitance of the VN/Ni3N–Ni/CC based supercapacitor with a nitriding temperature of 400 °C and a nitriding time of two hours can achieve a maximum areal capacitance of 845.63 mF cm−2 at a current density of 0.5 mA cm−2, and the electrode in the three-electrode system retains 86.1% of its initial capacitance value after 1500 cycles at a current density of 10 mA cm−2. In addition, the assembled flexible all-solid-state symmetric supercapacitor using the VN/Ni3N–Ni/CC electrode exhibits an areal capacitance ratio of 19.1 mF cm−2 at a current density of 0.4 mA cm−2 and excellent cycling stability. Moreover, it displays exceptional flexibility under different bending angles highlighting its potential for integration into flexible electronic devices. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) porous network structure self-assembled from birnessite-type MnO2 flakes and the urchin-like structure composed of MnO2 nanotubes were fabricated by a convenient one-step hydrothermal method by changing the amount of HCl as the sulfur scaffold for lithium–sulfur batteries. The perfect 3D interconnected nanostructure as a sulfur host displayed excellent electrochemical performance compared to the MnO2 tubes. Benefiting from the well-interconnected 3D spherical architecture, the MnO2/S cathode can reach a high specific capacity of 1582.9 mA h g−1 at 0.1C and a preferable cycling stability with excellent Coulombic efficiency. The porous 3D architecture and the interaction of the Mn–S chemical bond can not only facilitate electron transport, lithium diffusion, and relieve the volume expansion of S but can also effectively restrict the shuttling effect of soluble polysulfides generated during the charge–discharge process. [ABSTRACT FROM AUTHOR]