Ultra-stable Sb confined into N-doped carbon fibers anodes for high-performance potassium-ion batteries

Abstract

Antimony-based materials with high theoretical capacity are known as promising anodes for potassium-ion batteries (PIBs). However, they still face challenges from the large ionic radius of the K ion, which has sluggish kinetics. Much effort is needed to exploit high-performance electrode materials to satisfy the reversible capacity of PIBs. In this paper, nano Sb confined in N-doped carbon fibers (Sb@CN nanofibers) were successfully prepared through an electrospinning method, which was designed to improve potassium storage performances. Sb@CN nanofibers benefit from the fact that the synergy between the porous nanofiber frame structure and the uniformly distributed Sb nano-components in the carbon matrix can effectively accelerate the ion migration rate and reduce the mechanical stress caused by K+ insertion/extraction, Sb@CN nanofiber electrodes thus exhibited excellent potassium storage performance, especially long cycle stability, as expected. When utilized as a PIB anode, they delivered high reversible capacity of 360.2 mAh g−1 after 200 cycles at 50 mA g−1, and a particularly stable capacity of 212.7 mAh g−1 was also obtained after 1000 cycles even at 5000 mA g−1. Given such outstanding electrochemical performances, this work is expected to provide insight into the development and exploration of advanced alloy-type electrodes for PIBs.