As new and alternative energy storage devices to batteries and traditional capacitors, supercapacitors exhibit both high power and high energy density as well as good cycle life. NiCo2S4, a spinel‐structured transition metal sulfide with a high specific capacity, is considered to be a promising electrode material for supercapacitors with great application potential. However, the poor electrical conductivity of NiCo2S4 results in poor rate and cycle performance of the material, which limits its practical application. In this work, we design a composite by loading NiCo2S4 on the surface of carbon nanotubes (CNTs) to enhance the conductivity. The best‐performing CNTs@NiCo2S4 electrode materials were obtained after the optimized heat‐treatment of CNTs@SiO2 precursors. At a current density of 1 A g−1, the CNTs@NiCo2S4 composite exhibits a specific capacity of 216.4 mAh g−1 and a capacity retention of 75 % after 2000 cycles. Even at a high current density of 5 A g−1, the capacity can still retain 87 % of that under 1 A g−1. It is demonstrated that the electrochemical performance of NiCo2S4 can be effectively boosted by combining with conductive CNTs.
Aqueous zinc-ion batteries (ZIBs) have been regarded as a promising alternative to traditional lithium-based batteries due to their intrinsic advantages of safety, low cost, and abundance. However, the strong electrostatic interaction between Zn2+ and the layer-structured cathodes is still a key issue that hinders the batteries from storing more Zn. Herein, we report partially nitrided and cation-doped vanadium oxide for improved Zn storage performance. Specifically, the defects and nitride species that are generated inside the material upon nitriding improve the conductivity of the material and introduce a new Zn storage mechanism. The intercalation of cations, in contrast, widens the interlayer spacing to store more Zn2+ ions and enhances the cycling stability of the material. These merits synergistically lead to significantly enhanced electrochemical Zn2+ ion storage performance, in terms of a high specific capacity of 418.5 mAh·g−1 at a current density of 0.1 A·g−1 and a capacity retention of 81.2% after 500 cycles at 2.0 A·g−1. The new modification strategy for V2O5 suggested in this work could provide insight into the development of high-performance ZIBs.
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