Engineering CSFe Bond Confinement Effect to Stabilize Metallic‐Phase Sulfide for High Power Density Sodium‐Ion Batteries
Fei Wang, Zhendong Liu, Huiyan Feng, Yuchen Wang, Chengzhi Zhang, Zhuohua Quan, Lingxiao Xue, Zhenxing Wang, Songhao Feng, Chong Ye, Jun Tan, Jinshui Liu
Abstract
Abstract Metallic‐phase iron sulfide (e.g., Fe 7 S 8 ) is a promising candidate for high power density sodium storage anode due to the inherent metal electronic conductivity and unhindered sodium‐ion diffusion kinetics. Nevertheless, long‐cycle stability can not be achieved simultaneously while designing a fast‐charging Fe 7 S 8 ‐based anode. Herein, Fe 7 S 8 encapsulated in carbon‐sulfur bonds doped hollow carbon fibers (NHCFs‐S‐Fe 7 S 8 ) is designed and synthesized for sodium‐ion storage. The NHCFs‐S‐Fe 7 S 8 including metallic‐phase Fe 7 S 8 embrace higher electron specific conductivity, electrochemical reversibility, and fast sodium‐ion diffusion. Moreover, the carbonaceous fibers with polar CSFe bonds of NHCFs‐S‐Fe 7 S 8 exhibit a fixed confinement effect for electrochemical conversion intermediates contributing to long cycle life. In conclusion, combined with theoretical study and experimental analysis, the multinomial optimized NHCFs‐S‐Fe 7 S 8 is demonstrated to integrate a suitable structure for higher capacity, fast charging, and longer cycle life. The full cell shows a power density of 1639.6 W kg −1 and an energy density of 204.5 Wh kg −1 , respectively, over 120 long cycles of stability at 1.1 A g −1 . The underlying mechanism of metal sulfide structure engineering is revealed by in‐depth analysis, which provides constructive guidance for designing the next generation of durable high‐power density sodium storage anodes.