Covalent Organic Framework Mediated Solvation in Quasi-Solid-State Polymer Electrolyte for High-Performance Silicon-Based Lithium-Ion Batteries.

Cai, Tao; Zhao, Fei; Kumar, Pushpendra; Yu, Hao; Wang, Zexu; Huang, Akang; Wahyudi, Wandi; Li, Qian et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

The practical application of solid polymer electrolytes (SPEs) is limited by their low ionic conductivity and poor interfacial compatibility with silicon (Si) anodes in high-energy-density, safe lithium-ion batteries (LIBs). Here, we introduce a lithiated covalent organic framework (COF) into a poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP)-based quasi-solid polymer electrolyte (QSPE) containing plasticizers to increase its electrochemical performance. The resulting COF-based QSPE has a high ionic conductivity of 2.99 mS cm<sup>-1</sup> and enables Si anodes to deliver a remarkable specific capacity of 1722 mAh g<sup>-1</sup> after 500 cycles, along with an excellent rate capability of up to 10 A g<sup>-1</sup>. Furthermore, we provide new insights into the role of lithiated COFs in modulating the Li<sup>+</sup> solvation structure, facilitating ionic migration and promoting desolvation in plasticizer-containing solid electrolytes at the molecular scale. These findings offer valuable guidelines for the rational design of stable Si anodes in solid-state batteries.