MoS2 encapsulated FeS2 composite anchored on graphite substrate for high-performance sodium-ion batteries

Abstract

Transition metal sulfides (TMSs) are currently recognized as promising anode materials for sodium-ion batteries owing to their high theoretical capacities and relatively weak M–S bonds. However, TMSs face significant challenges during cycling, particularly poor electronic conductivity and severe volume expansion, impeding their practical applications. In this study, FeS2–MoS2/C multicomponent composite materials are synthesized through a molten salt synthesis route, followed by high-temperature sulfurization. The FeS2–MoS2 heterostructure significantly improves both ion and electron transfer, offering a wealth of active sites. The graphite carbon layer acts as a robust support and conductive framework for FeS2–MoS2, ensuring uniform dispersion of active components. This unique architecture, combined with the asynchronous redox behavior of FeS2 and MoS2, effectively mitigates volume expansion during sodium insertion/extraction, maintaining structural stability and improving the cycling stability of the electrode material. The FeS2–MoS2/C composite exhibits exceptional electrochemical performance, achieving a sustained specific capacity of 478.5 mA h g−1 after 3000 cycles at 5000 mA g−1, with an impressive capacity retention rate of 97.2%. Additionally, it demonstrates excellent rate capability and high-temperature adaptability. Even at 60 °C, the electrode delivers a reversible discharge capacity of 515.6 mA h g−1 after 600 cycles at 2 A g−1.