Denize Clifford, Behera Makhes K, Pradhan Sangram K, Bahoura Messaoud
Center for Materials Research, Norfolk State University, 700 Park Ave., Norfolk, VA, 23504, USA.
Virginia Alliance for Semiconductor Technology, Arlington, VA, 22201, USA.
Sci Rep. 2025 Aug 27;15(1):31653. doi: 10.1038/s41598-025-17485-1.
Pyrite (FeS) thin films have attracted significant attention as promising cathode materials for lithium-ion batteries due to their high theoretical capacity, natural abundance, and environmental benignity. However, due to sulfur volatility during film deposition, achieving stoichiometric FeS remains challenging. In this study, we investigate the effects of post-deposition sulfurization treatment on the chemical composition, crystal structure, and electrochemical performance of FeS thin films synthesized by RF magnetron sputtering. The as-deposited films exhibit notable sulfur deficiency, with an S: Fe atomic ratio of 0.27:1, while a 4-hour sulfurization process improves the ratio to 1.97:1, approaching ideal stoichiometry. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirm the formation of the pyrite phase, and X-ray diffraction (XRD) and field effect emission scanning electron microscopy (FESEM) reveal enhanced crystallinity and polycrystalline growth. Electrochemical analysis using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) demonstrates that sulfurized films deliver superior initial and long-term (100-cycle) discharge specific capacities compared to as-deposited samples. The improved performance is attributed to optimized surface stoichiometry, increased reducibility, and the formation of stable intermediate phases. These findings underscore the critical role of sulfurization in tuning the structural and electrochemical properties of FeS thin-film cathodes and present a viable strategy for enhancing the performance and stability of conversion-type cathodes in lithium-ion batteries.
黄铁矿（FeS）薄膜因其高理论容量、天然丰度和环境友好性，作为锂离子电池有前景的阴极材料受到了广泛关注。然而，由于薄膜沉积过程中硫的挥发性，实现化学计量比的FeS仍然具有挑战性。在本研究中，我们研究了沉积后硫化处理对通过射频磁控溅射合成的FeS薄膜的化学成分、晶体结构和电化学性能的影响。沉积态薄膜表现出明显的硫缺乏，S:Fe原子比为0.27:1，而4小时的硫化过程将该比例提高到1.97:1，接近理想化学计量比。X射线光电子能谱（XPS）和拉曼光谱证实了黄铁矿相的形成，X射线衍射（XRD）和场发射扫描电子显微镜（FESEM）显示结晶度增强和多晶生长。使用循环伏安法（CV）和恒电流充放电（GCD）进行的电化学分析表明，与沉积态样品相比，硫化薄膜具有更高的初始和长期（100次循环）放电比容量。性能的提高归因于优化的表面化学计量比、增加的还原性以及稳定中间相的形成。这些发现强调了硫化在调节FeS薄膜阴极的结构和电化学性能方面的关键作用，并提出了一种提高锂离子电池中转换型阴极性能和稳定性的可行策略。
