SnS₂/N-Doped Graphene as a Superior Stability Anode for Potassium-Ion Batteries by Inhibiting “Shuttle Effect”

Potassium-ion batteries are promising supplements to lithium-ion batteries considering the abundance of potassium. However, the high reactivity of metallic potassium and low capacity of graphite anode are great challenges. A high capacity anode material is desired. Herein, we synthesize a tin sulfide/N-doped reduced graphene oxide composite (SnS₂/N-rGO), in which tin sulfide nanoparticles are dispersed on the N-doped graphene layer. It shows a high reversible capacity of 645.2 mAh g⁻¹ at 50 mA g⁻¹ and 402 mAh g⁻¹ at 1 A g⁻¹. In situ X-ray powder diffraction of the discharge process is carried out. KSn forms as a final product and K₂S₅ forms as an important discharge intermediate. Nitrogen-doping immobilizes the tin sulfide particles and inhibits the loss of polysulfide intermediate. Therefore, 97.3 % of discharge capacity remains after 100 cycles. This result sheds light on the rational design of anode materials with large volume change for potassium ion batteries.