Structural design and performance optimization of different crystalline zinc sulfide anodes in sodium-ion batteries

Zinc sulfide (ZnS) has been recognized as a promising anode material for sodium-ion batteries, owing to its high theoretical capacity, natural abundance, and low cost. However, its practical application is hindered by challenges such as volume expansion, limited reaction kinetics, and irreversible capacity loss. To effectively understand and address these challenges, it is essential to investigate the distinct structural and electrochemical properties of ZnS's two crystalline forms: wurtzite and sphalerite. Among them, sphalerite type ZnS, with a cubic symmetric structure, facilitates the rapid sodium-ion diffusion and high-rate performance, but its cycling stability tends to be compromised by structural collapse induced by volume changes. In contrast, wurtzite type ZnS, featuring a hexagonal structure, can provide the enhanced stability and an extended cycle life due to its more open structure, albeit with slower ion transport. To further elucidate the advantages and limitations of various ZnS materials as sodium-ion battery anodes, this paper discusses the mechanisms by which tailored strategies—such as heterostructure design, carbon composite integration, and electrolyte optimization to enhance the performance of ZnS anodes. In addition, the challenges and future prospects for further optimizing the electrochemical performance of ZnS are outlined. The insights provided herein are anticipated to serve as valuable references for the commercialization of ZnS and analogous anode materials in the sodium-ion battery industry.