Nano-engineering induced Bi dots in situ anchored into modified porous carbon with superior sodium ion storage

Abstract

Bismuth-based materials have aroused extensive interest in energy storage systems owing to their high volumetric capacity, relatively low reaction potential, and minimum volume changes compared with their alloy counterparts. However, the cumbersome synthetic routes and low initial coulombic efficiency (ICE) are the main issues that still need to be resolved. Herein, Bi dots in situ embedded in a KOH modified carbon matrix (Bi@MC) have been successfully fabricated via a facile annealing process. The KOH modification endows the carbon matrix with a strong absorption ability, which can further suppress the agglomeration of Bi and lead to uniformly distributed Bi dots (3–18 nm). For the half-cell test, a high ICE (88.13%), record ultra-stable cycle life (100% capacity retention over 10 000 cycles at 2.5 A g⁻¹) and a superior rate performance (345 mA h g⁻¹ at 50 A g⁻¹) can be realized. Furthermore, the Na₃V₂(PO₄)₃|Bi@MC full cell delivers an excellent energy density of up to 195 W h kg⁻¹ and behaves with no capacity decay over 600 cycles.