Construction of Sb2S3@NC Core-Shell Nanorod with Hollow Feature as Anode via Microstructure Regulation Strategy for High-Performance Na⁺/K⁺ Storage

Abstract

Antimony trisulfide (Sb2S3) is a highly promising anode material for alkali-metal batteries due to its high theoretical capacity and abundant resources. However, severe volume expansion during charge-discharge and low electrical conductivity restrict its electrochemical performance. In this study, Sb2S3@NC core-shell nanorod with hollow feature (H-Sb2S3@NC) was successfully prepared via high-temperature carbonization and secondary sulfidation of the inorganic-organic Sb2S3@PDA composite precursor. It would induce the volatilization of partial Sb2S3 by controlling temperature during carbonization, concurrently forming the inorganic core-shell nanorod structure and its hollow feature. Compared to Sb2S3@NC without hollow feature, H-Sb2S3@NC exhibits superior cycling and rate performance when as anode for sodium-ion (SIBs) and potassium-ion batteries (PIBs). Specifically, as anode for SIBs, H-Sb2S3@NC retains 517.0 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹ and even delivers 535.5 mAh g⁻¹ at 1000 mA g⁻¹ (Sb2S3@NC: 60.6 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹, 39.7 mAh g⁻¹ at 1000 mA g⁻¹). For PIBs, H-Sb2S3@NC provides 431.1 mAh g⁻¹ after 50 cycles at 100 mA g⁻¹ (Sb2S3@NC: 208.3 mAh g⁻¹ under the same conditions). Ex situ characterizations confirm Sb2S3 undergoes a reversible conversion-alloying reaction during Na⁺/K⁺ storage. The internal voids of H-Sb2S3@NC could effectively buffer volume expansion stress, while N-doping in the NC (nitrogen-doped carbon) layer enhances ion/electron transport. These two factors synergistically ensure electrode structural stability and excellent kinetics. The temperature-controlled microstructure regulation strategy proposed in this study provides an effective approach to addressing the volume expansion problem of Sb2S3-based anodes and optimizing the electrode performance of alkali-metal ion batteries.