Additive-Specific SEI Nanostructures on Silicon Anodes Revealed by Cryo-TEM and EELS under Suppressed Bulk Alloying

作者：Zheng Zhang, Yuxuan Cui, Xiaomin Huang, Menghao Li, Xianbin Wei, Cheng Zhen, Chao Cai, Duojie Wu, Li Deng, Zhiyuan Zeng, Ruyi Zhong, M. Danny Gu · 发表于：Nano Letters · 年份：2026 · DOI：10.1021/acs.nanolett.6c00141 · 被引用次数：1 · 研究领域：Advancements in Battery Materials、Advanced Battery Materials and Technologies、Fiber-reinforced polymer composites

Silicon anodes suffer from unstable solid electrolyte interphases (SEI) that drive capacity fade. Here, using low-dose cryogenic TEM and EELS under suppressed bulk Li–Si alloying (0.1 V vs Li/Li + cutoff, 10 cycles), we resolve the atomic-scale SEI nanostructures induced by fluoroethylene carbonate (FEC), ethylene sulfite (ES), and lithium difluorophosphate (LiPO 2 F 2 ). FEC forms a dense ∼20 nm LiF-rich nanocrystal scaffold, ES produces a 10–20 nm heterogeneous mosaic of LiF/Li 2 SO 4 within an organic-rich matrix, and LiPO 2 F 2 yields an ultrathin (∼10 nm) inorganic-dominated but brittle layer. Despite being the thickest, the FEC-derived SEI delivers the best long-term cycling stability. Mechanistically, optimal performance arises from a balanced architecture that combines strong electronic insulation, efficient Li + transport across grain boundaries, and mechanical coherence rather than minimized thickness alone. These findings identify composition and nanostructural continuity as key regulators of interfacial stability in silicon anodes.