Regulation of Lithium-Ion Flux by Nanotopology Lithiophilic Boron-Oxygen Dipole in Solid Polymer Electrolytes for Lithium-Metal Batteries

Abstract

Inhomogeneous lithium-ion (Li⁺) deposition is one of the most crucial problems, which severely deteriorates the performance of solid-state lithium metal batteries (LMBs). Herein, we discovered that covalent organic framework (COF-1) with periodically arranged boron-oxygen dipole lithiophilic sites could directionally guide Li⁺ even deposition in asymmetric solid polymer electrolytes. This in situ prepared 3D cross-linked network Poly(ACMO-MBA) hybrid electrolyte simultaneously delivers outstanding ionic conductivity (1.02 × 10⁻³ S cm⁻¹ at 30 °C) and excellent mechanical property (3.5 MPa). The defined nanosized channel in COF-1 selectively conducts Li⁺ increasing Li⁺ transference number to 0.67. Besides, The COF-1 layer and Poly(ACMO-MBA) also participate in forming a boron-rich and nitrogen-rich solid electrolyte interface to further improve the interfacial stability. The Li‖Li symmetric cell exhibits remarkable cyclic stability over 1000 h. The Li‖NCM523 full cell also delivers an outstanding lifespan over 400 cycles. Moreover, the Li‖LiFePO₄ full cell stably cycles with a capacity retention of 85% after 500 cycles. the Li‖LiFePO₄ pouch full exhibits excellent safety performance under pierced and cut conditions. This work thereby further broadens and complements the application of COF materials in polymer electrolyte for dendrite-free and high-energy-density solid-state LMBs.