Schottky Junction and Multiheterostructure Synergistically Enhance Rate Performance and Cycling Stability

Abstract Constructing Schottky junction and multiheterostructure is considered a promising modification strategy to enhance reaction kinetics and prolong cycle life for alkali ion batteries, especially for potassium-ion batteries (KIBs) with sluggish kinetics and huge volume expansion. Herein, a well-designed multiheterostructure of SnS@C@MoS2@NC micronflower is successfully synthesized, which consists of SnS, intermediate carbon, MoS2 and N-doped carbon from interior to exterior. The Schottky junction with built-in electric-field induced by phase boundaries and the double carbon layers (intermediate carbon and N-doped carbon coating layer) significantly improve the electrons transfer rate, and simultaneously the multiheterostructure affords rapid K+ diffusion, strong K absorption and boosted electronic conductivity, resulting in superior charge transfer kinetics, which is explicitly unraveled by experimental results and first-principles calculations. Moreover, this multilayered structure with double carbon layers can effectively buffer the volumetric variation and maintain structural stability. Benefiting from these merits, the SnS@C@MoS2@NC anode delivers remarkable reversible capacity (471 mAh g−1 at 50 mA g−1 after 100 cycles), outstanding rate performance (305 mAh g−1 at 1000 mA g−1) and ultralong lifespan (253 mAh g−1 at 1000 mA g−1 after 3000 cycles) for KIBs. This work sheds a light on fabricating advanced electrodes by utilizing the Schottky junction and multiheterostructure.