Multi-shell hollow structured Sb₂S₃ for sodium-ion batteries with enhanced energy density

Abstract

Low energy density is the key issue that needs to be addressed for sodium ion batteries. Antimony sulfide (Sb₂S₃) with high theoretical capacity is considered as an ideal anode, but it suffers from poor electrochemical activity and consequently, low energy density. Simple hollow Sb₂S₃ structures with high electrochemical activity offer high gravimetric energy density, while large internal voids significantly decrease the volumetric energy density. Here, multi-shell Sb₂S₃ was synthesized as an anode for sodium ion batteries, exhibiting much higher reversible capacity and gravimetric energy density than the pristine Sb₂S₃. Moreover, the multi-shell structure presents higher volumetric energy density with enhanced durability than its single-shell counterpart due to the optimized utilization of the inner void. Operando synchrotron-based X-ray powder diffraction (XRPD) was used to verify the enhanced electrochemical activity originated from more complete conversion electrochemical reactions. The multi-shell Sb₂S₃ design may provide a guide for the development of high-performance hollow structured anodes with preserved high energy density.