Surface-Confined SnS₂ @C@rGO as High-Performance Anode Materials for Sodium- and Potassium-Ion Batteries

Potassium- (PIBs) and sodium-ion batteries (SIBs) are emerging as promising alternatives to lithium-ion batteries owing to the low cost and abundance of K and Na resources. However, the large radius of K⁺ and Na⁺ lead to sluggish kinetics and relatively large volume variations. Herein, a surface-confined strategy is developed to restrain SnS₂ in self-generated hierarchically porous carbon networks with an in situ reduced graphene oxide (rGO) shell (SnS₂ @C@rGO). The as-prepared SnS₂ @C@rGO electrode delivers high reversible capacity (721.9 mAh g^-1 at 0.05 A g^-1 ) and superior rate capability (397.4 mAh g^-1 at 2.0 A g^-1 ) as the anode material of SIB. Furthermore, a reversible capacity of 499.4 mAh g^-1 (0.05 A g^-1 ) and a cycling stability with 298.1 mAh g^-1 after 500 cycles at a current density of 0.5 A g^-1 were achieved in PIBs, surpassing most of the reported non-carbonaceous anode materials. Additionally, the electrochemical reactions between SnS₂ and K⁺ were investigated and elucidated.