Enhancing the Interfacial Stability of Thin Solid Polymer Electrolyte with Fluorinated Covalent Organic Framework Nanosheets
Tao Liu, Yuan Zhong, Xiangyu Gao, Jun Jiang, Lingyi Jiang, Boying He, Yichen Liu, Zhiyi Ling, Hao Xu, Hongmin Guo, Jialiang Zhu, Bingqing Xu, Gen Zhang
Abstract
Thin poly(ethylene oxide) (PEO)-based electrolytes with higher energy density face challenges such as low ionic conductivity, deterioration of lithium dendrites, and severe side reactions. To address these issues, a surface modification strategy was developed to enhance the electrode–electrolyte interfacial stability by introducing fluorinated covalent organic framework nanosheets (CONs) to construct a thin PEO-based electrolyte with a mere 14 μm thickness. Characterization and DFT calculation indicated that the CON layer promotes concentration enrichment and averaging of free Li + and mitigates side reactions at the interface. The electrode/electrolyte interface stability is significantly improved compared to the unmodified group (Li symmetric cells stabilized for more than 1000 h, and the full cell of LiFePO 4 ∥Li exhibited a satisfactory capacity retention of 97.3% at 0.5 C after 150 cycles at 60 °C. This interface modification strategy provides a valuable reference for applying thin polymer electrolytes in high-energy solid-state lithium metal batteries.