Interface Modulation of Metal Sulfide Anodes for Long‐Cycle‐Life Sodium‐Ion Batteries

• Published in: Advanced materials (Weinheim) 2023-03, Vol.35 (13), p.e2208705-n/a
• Main Authors: Yang, Mei, Chang, Xiaoqing, Wang, Liuqi, Wang, Xingyu, Gu, Mengyan, Huang, Hao, Tang, Lingyu, Zhong, Yiren, Xia, Hui
• Format: Article
• Language: English
• Subjects: anion decomposition; Anions; Anodes; capacity decay mechanism; Decomposition reactions; Electrode materials; Electrolytes; Failure mechanisms; interface modulation; Iron sulfides; Materials science; Metal sulfides; Sheaths; Sodium; sodium ion storage; Sodium nitrates; Sodium-ion batteries; Solvation; Transition metals
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202208705

Although studies of transition metal sulfides (TMS) as anode materials for sodium‐ion batteries are extensively reported, the short cycle life is still a thorny problem that impedes their practical application. In this work, a new capacity fading mechanism of the TMS electrodes is demonstrated; that is, the parasitic reaction between electrolyte anions (i.e., ClO4−) and metal sulfides yields non‐conductive and unstable solid‐electrolyte interphase (SEI) and meanwhile, corrosively turns metal sulfides into less‐active oxides. This knowledge guides the development of an electrochemical strategy to manipulate the anion decomposition and construct a stable interface that prevents extensive parasitic reactions. It is shown that introducing sodium nitrate to the electrolyte radically changes the Na+ solvation structure by populating nitrate ions in the first solvation sheath, generating a stable and conductive SEI layer containing both Na3N and NaF. The optimized interface enables an iron sulfide anode to stably cycle for over 2000 cycles with negligible capacity loss, and a similar enhancement in cycle performance is demonstrated on a number of other metal sulfides. This work discloses metal sulfides’ cycling failure mechanism from a unique perspective and highlights the critical importance of manipulating the interface chemistry in sodium‐ion batteries. A new capacity fading mechanism of metal sulfide electrode materials is discovered, that is, the parasitic reaction between electrolyte anions and metal sulfides. Herein, a universal strategy is proposed to manipulate the electrolyte decomposition and construct a stable and ion‐conductive solid electrolyte interphase that prevents the corrosive side reactions and leads to prolonged cycle life.