Fluorine-doped porous carbon coating on Sn/SnOx as anode materials for high-performance potassium ion batteries

Potassium-ion batteries (PIBs) are considered alternatives to lithium-ion batteries because of their comparatively cheaper manufacturing costs and lower potential (2.936 V compared to standard hydrogen electrodes). However, their large ionic radii and unstable structures hindered their satisfactory electrochemical performance. In this study, F-Sn/SnOx@C, a novel porous layered composite material, was prepared using NaCl as a template for in situ etching to obtain a promising negative electrode material for PIBs. The significant specific surface area of the composite material and the uniform embedding of tin nanoparticles within the layered porous carbon shell, contributed to its excellent potassium intercalation/deintercalation performance. Fluorine doping enhanced electron transfer, prevented nanoparticle aggregation, and improved electrolyte penetration and potassium ion migration. The PIBs prepared from this electrode showed high potassium storage capacity, outstanding cycle stability (retaining 263 mAh g-1 after 200 cycles at 100 mA g-1), and remarkable rate capability (505.6, 288.4, 193.5, 134.1, and 83.3 mAh g-1 at 0.1, 0.2, 0.3, 0.5, and 1.0 A g-1, respectively). These results provide a straightforward solution for improving the electrochemical performance of PIBs.