Built-in electric field induced interfacial effect enables ultrasmall SnS nanoparticles with high-rate lithium/sodium storage

• SnS x /N-rGO-30 with rich heterostructures was prepared by a hydrothermal route. • Built-in electric field greatly accelerates the charge transfer and ion diffusion. • SnS x /N-rGO-30 shows high Li + storage capacity of 1273 mAh g −1 at 0.1 A g −1 . • SnS x /N-rGO-30 shows high Na + storage capacity of 640 mAh g −1 at 0.1 A g −1 . Metal sulfides have been broadly used as potential candidates in lithium-ion and sodium-ion batteries. However, they usually undergo huge volume expansion and shrinkage, inferior electronic conductivity and sluggish redox reaction kinetics. Construction of heterostructure turns out to be a successful route to accelerate the charge transfer kinetics. Herein, ultrafine SnS x nanoparticles (∼5 nm) with abundant heterostructure are anchored on N-doped graphene through a hydrothermal approach. The rich heterostructures and the interfacial effect induced by built-in electric field significantly accelerate the charge transport and ion diffusion. The SnS x /N-rGO-30 nanocomposite displays large discharge capacity of 1273 mAh g −1 at 0.1 A g −1 , superior rate ability (594 mAh g −1 even at 10 A g −1 ) as well as excellent cycling performance as anodes for Li-ion batteries. As for sodium-ion storage, the SnS x /N-rGO-30 nanocomposite exhibits high reversible capacity of 640 mAh g −1 at 0.1 A g −1 and high rate capability of 225 mAh g −1 at 10 A g −1 .