Bifunctional flame retardant solid-state electrolyte toward safe Li metal batteries

Solid polymer electrolytes (SPEs) are one of the most promising alternatives to flammable liquid elec-trolytes for building safe Li metal batteries. Nevertheless, the poor ionic conductivity at room tempera-ture (RT) and low resistance to Li dendrites seriously hinder the commercialization of SPEs. Herein, we design a bifunctional flame retardant SPE by combining hydroxyapatite (HAP) nanomaterials with N-methyl pyrrolidone (NMP) in the PVDF-HFP matrix. The addition of HAP generates a hydrogen bond net-work with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of LiTFSI in the PVDF-HFP matrix. Consequently, the prepared SPE demonstrates superior ionic conductivity at RT, excel-lent fireproof properties, and strong resistance to Li dendrites. The assembled Li symmetric cell with pre-pared SPE exhibits a stable cycling performance of over 1200 h at 0.2 mA cm-2, and the solid-state LiFePO4||Li cell shows excellent capacity retention of 85.3% over 600 cycles at 0.5 C.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

A bifunctional flame retardant solid polymer electrolyte (SPE) is designed by combining hydroxyapatite (HAP) nanomaterials and N-methyl pyrrolidone (NMP) with the PVDF-HFP matrix. The prepared SPE shows superior ionic conductivity, excellent fireproof properties, and strong resistance to Li dendrites.