Metal sulfoselenide solid solution embedded in porous hollow carbon nanospheres as effective anode material for potassium-ion batteries with long cycle life and enhanced rate performance

Recently, potassium-ion batteries (KIBs) have been investigated as promising alternative to lithium-ion batteries, and significant advances in terms of new compositions and nanostructures are being made. In this regard, the strategy of introducing hetero-anions into metal compounds has been considered as an innovative method. After the initial electrochemical reaction, hetero-anion metal compounds are divided into individual metal compounds to form heterointerfaces, thus enhancing the electrochemical kinetics. Herein, a new strategy for the synthesis of metal sulfoselenide solid solution embedded in the porous shells of hollow carbon nanospheres is introduced; here, porous hollow carbon nanospheres are utilized as a co-infiltrating matrix to create electrode material with robust stability and high conductivity. The conversion reaction mechanism of metal sulfoselenide with potassium ions was investigated through systematic structural and electrochemical analyses, where metal sulfide/metal selenide hetero-interface was formed after the initial cycle. As anode for KIBs, CoSSe–C exhibited impressive electrochemical properties including particularly long cycle life (286 mA h g⁻¹ for 3000 cycles at 1.5 A g⁻¹) and excellent rate capability (185 mA h g⁻¹ at 5.0 A g⁻¹).