Heterostructured CoS2/CuCo2S4@N-doped carbon hollow sphere for potassium-ion batteries

Potassium ions batteries (PIBs) have been regarded as a promising choice for electrical energy storage technology due to the wide distribution of potassium resources. However, developing low-cost and robust earth-rich anode materials is still a major challenge for the practical and scalable usage of PlBs. Herein, for the first time, we developed nitrogen doped carbon coating CoS2/CuCo2S4 heterostructure (CoS2/CuCo2S4 @NCs) hollow spheres and evaluated as anode for PlBs. The CoS2 and CuCo2S4 heterostructure interface could generate a built-in electric field, which can fasten electrons transportation. The nanostructures could shorten the diffusion length of K+ and provide large surface area to contact with electrolytes. Furthermore, the inner hollow sphere morphology along with the carbon layer could accommodate the volume expansion during cycling. What's more, the N-doped carbon could increase the conductivity of the anodes. Benefitting from the above features, the CoS2/CuCo2S4@NCs displays an outstanding rate capability (309 mAh g at 500 mA g after 250 cycles) and a long-term cycling life (112 mAh g (1) at 1000 mA g (1) after 1000 cycles) in ether-based electrolyte. Conversion reaction mechanism in CoS2/CuCo2S4 @NCs anode is also revealed through ex situ XRD characterizations. This work provides a practical direction for investigating metal sulfides as anode for PlBs. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

A new nitrogen doped carbon coating CoS2/CuCo2S4 heterostructure was developed as an anode for potassium ions batteries, demonstrating outstanding rate capability and long-term cycling life. Additionally, the conversion reaction mechanism in the anode was revealed through ex situ XRD characterizations.