Pomegranate-like heterostructured SnS2/CoS2 particles encapsulated in S, N dual-doped carbon framework enabling high-rate and durable sodium ion storage

As a promising anode material for sodium-ion batteries, SnS ₂ has attracted increasing attention owing to its high theoretical capacity and abundant reserves. Unfortunately, the poor electrical conductivity and drastic volume changes lead to unsatisfactory cycling and rate performance, largely limiting its practical application. Herein, we report a pomegranate-like composite of heterostructured SnS ₂/CoS ₂ spheres encapsulated in S, N dual-doped carbon framework (SnS ₂/CoS ₂@SNC) obtained by a simple ion adsorption, in situ polymerization coating of polydopamine and subsequent calcination strategy. The integration of CoS ₂ with SnS ₂ particles with abundant interfaces can provide rich redox chemistry and accelerated ion diffusion kinetics, while the coated S, N dual-doped carbon shell enables good electrical conductivity and reinforced structural integrity as well by accommodating the volume changes and inhibiting the collapse/pulverization of active materials during the cycling process. As a consequence, the pomegranate-like heterostructured SnS ₂/CoS ₂@SNC anode exhibited a higher capacity (743 mAh g ⁻¹ at 1 A g ⁻¹), excellent rate capability (213 mAh g ⁻¹ at 50 A g ⁻¹) and outstanding cycling stability (560 mAh g ⁻¹ at 5 A g ⁻¹ after 1000 cycles), showing the application feasibility of this anode material for developing high-rate and durable SIBs.