Boosting the transport kinetics of free-standing SnS2@Carbon nanofibers by electronic structure modulation for advanced lithium storage

Abstract

Tin-based materials with high capacity and long life are significant to the development of lithium-ion batteries (LIBs). Herein, free-standing Mg doped SnS₂/CNF (Mg–SnS₂/CNFs) composites are prepared via electrospinning and subsequent carbonization and sulfidation. Mg-doping promotes the Li-ion diffusion kinetics of SnS₂ by decreasing the activation energy and improving the pseudocapacitance contribution. The inhibition of pulverization ensures high reversibility and good cycling stability of the Mg–SnS₂/CNF anode. Density functional theory calculations reveal that Mg doping effectively induces the redistribution of electrons to generate internal electrical fields, accelerating the transport kinetics of Li ions and electrons at interlayers. The excellent ion transport kinetics endows Mg–SnS₂/CNF electrodes with an excellent rate capacity (354.7 mA h g⁻¹ at 20 A g⁻¹ and 207.1 mA h g⁻¹ at 30 A g⁻¹) and an outstanding cyclability (792.5 mA h g⁻¹ at 1 A g⁻¹ for 1000 cycles) in LIBs. This work provides insights into the modulation strategies of electrodes to improve the reaction kinetics and lithium storage.