Two-dimensional silica enhanced solid polymer electrolyte for lithium metal batteries

Solid polymer electrolytes (SPEs) are promising substitutes for current flammable liquid electrolytes to achieve high-safety and high-energy-density lithium metal batteries. Polyethylene oxide (PEO) based solid polymer electrolytes have attracted increasing attention because of their excellent flexibility, manufacturability, light weight, and low-cost processing, while they often suffer from low ionic con-ductivity at room temperature, low lithium transference number and unsatisfactory interfacial resis-tance, which largely restrain their practical application. Herein, two-dimensional holey silica nanosheets (2D-HSN) as the fillers, together with LiNO3 as the electrolyte additive, are introduced in a PEO/poly(-vinylidene fiuoride-co-hexafluoropropylene) (PVDF-HFP) blended polymer matrix to obtain a SPE. The incorporation of HSN filler creates supplementary channels for lithium ion migration and lowers the crystallinity of the polymer, thereby facilitating the movement of lithium ions. The HSN-based SPE demonstrates higher ionic conductivity up to 3.7 x 10-4 S cm-1 at 30 degrees C, larger Li+ transference number close to 0.34, and more stable lithium plating/stripping than that without the fillers, and HSN can promote the formation of more stable solid electrolyte interphase (SEI) layer. The as-assembled LiFePO4|| Li batteries deliver a high specific capacity of 159 mA h g-1 with the capacity retention of 95.5% after 200 cycles at 30 degrees C, as well as superior rate performance and cycling stability compared to that using the blank SPE.(c) 2023 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.