Heterogeneous cobalt polysulfide leaf-like array/carbon nanofiber composites derived from zeolite imidazole framework for advanced asymmetric supercapacitors

Developing new electrode materials is one of the keys to improving the energy density of supercapaci-tors. In this article, a novel cobalt polysulfide/carbon nanofibers (C,N-CoxSy/CNF) film derived from zeo-litic imidazolate framework is first prepared by a facile strategy. The composite material with two-dimensional leaf-shaped nanoarray neatly grown on the surface of carbon nanofibers is composed of CoS, CoS2, Co9S8, N-doped carbon nanosheets, and carbon nanofibers. It is found that the composite can not only increase the contact area with the electrolyte but also provide abundant redox-active sites and a Faraday capacitance for the entire electrode. The C,N-CoxSy/CNF composite exhibits excellent electrochemical properties, including a high capacity of up to 1080F g(-1) at 1 A g(-1) and a good rate capability (80.4 % from 1 A g(-1) to 10 A g(-1)). A C,N-CoxSy/CNF//AC asymmetric supercapacitor device is assembled using C,N-CoxSy/CNF as the positive electrode and activated carbon as the negative electrode, showing high energy density (37.29 Wh kg(-1)@813.6 W kg(-1)) and good cycle stability (90.5% of initial specific capacitance at 10 g(-1) after 5000 cycles). This C,N-CoxSy/CNF composite material may also be used as a potential electrode for future lithium-ion batteries, zinc-ion batteries, lithium-sulfur batteries, etc. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This article presents a novel CN-CoxSy/CNF composite material that can enhance the energy density and electrochemical properties of supercapacitors. The composite exhibits high capacity and good cycle stability, making it a potential electrode material for various batteries in the future.