In-situ gas reduction in reversible SnS-SnO₂@N-doped graphene anodes for high-rate and lasting lithium storage

Ameliorating the conductivity and terrible phase aggregation are the primary tasks of tin-based anodes for practical applications in lithium storage. Inspired by this, we have adopted an in-situ gas reduction strategy for fine SnS-SnO₂ nanoparticles anchoring uniformly on N-doped graphene (C@SnS-SnO₂@NGr) to realize superior rate performance in lithium-ion batteries (LIBs) applications. Especially, the better electric contact between SnS and SnO₂ can avoid localized reaction of SnM_x (M signifies O/S) and retard serious aggregation of Sn/Li_xSn. As a result, a higher initial Coulombic efficiency (ICE) (78%) was achieved with almost reversible conversion reaction of Sn/Li₂M. The capacity retention reaches around 85% at the current density of 0.1 A g⁻¹ for 500 cycles (1120 mA h g⁻¹). Besides, the N-doped graphene as the skeleton benefits the well-distribution of p-n SnS-SnO₂ nanoparticles and the conductivity of hybrids. Through high-rate and longest evaluation of 2.0 A g⁻¹, the unique anode still keeps a high capacity of 630 mA h g⁻¹ above 1000 cycles, which accordingly reveals a dominated surface-controlled redox reaction. Correspondingly, the evolution of electrode indicates that the ameliorate conductivity by N-doped graphene and the in-situ gas reduction procedure indeed enhance the charge-transfer kinetics and contribute to a durable high-rate performance.