Synthesis of CoSe2 reinforced nitrogen-doped carbon composites as advanced anodes for potassium-ion batteries

Abstract

Potassium-ion batteries (PIBs) are considered potential candidates for large-scale energy storage applications with cost superiority. However, the development of PIBs is severely restricted by the sluggish electrochemical kinetics and severe volume expansion of anode materials. Herein, CoSe₂ reinforced nitrogen-doped carbon composites (CoSe₂@C) are synthesized via a simple solution-based etching-coating method and further studied as high-performance anodes for PIBs. Electrochemical characterization studies indicate that the potassium storage performance of CoSe₂@C composite anodes relies on the initial mass ratio of CoSe₂ nanosheets and carbon precursors (that is dopamine hydrochloride) during the synthesis process. In the case of the mass ratio of CoSe₂ nanosheets and dopamine hydrochloride being 1 : 1, the as-obtained CoSe₂@C-1 : 1 anode exhibits a high reversible capacity (366.1 mA h g⁻¹ at 0.1 A g⁻¹ after 100 cycles), an excellent long-cycle stability (237.6 mA h g⁻¹ at 1.0 A g⁻¹ after 1000 cycles), and a good rate capability (281.5 mA h g⁻¹ at 5.0 A g⁻¹). The optimum performance of CoSe₂@C-1 : 1 as a PIB anode in terms of cycling stability and kinetics is attributed to the uniform distribution of CoSe₂ nanoparticles inside the carbon matrix.