Constructing hollow CoSe2/SnSe2 heterostructures covered with N-doped carbon shell for high-efficiency potassium-ion storage

Potassium ion batteries (KIBs) are competitive energy storage systems for large-scale applications. However, developing suitable electrode materials to allow KIBs to achieve high electrochemical performances remains a significant challenge owing to the large radius of K+. In this study, hollow nanostructures composed of tin–cobalt bimetallic selenides and an N-doped carbon sheath ([email protected]) were successfully fabricated from CoSn(OH)6 precursors via simple polydopamine coating and subsequent selenization. The synergy of the two active species and the structural features promoted electrochemical redox reactions and alleviated volume expansion during cycling. Moreover, the N-doped carbon coating reinforced the nanocomposite against particle pulverization while improving the electrode conductivity. Consequently, when tested as an anode for KIBs, the [email protected] electrode exhibited a high potassium storage performance, remarkable cycling performance of 370 mA h g−1 at 0.5 A g−1 after 200 cycles, and excellent rate capability of 184 mA h g−1 at 2.0 A g−1. Thus, this electrode shows potential for practical use in the energy storage field.