A Flexible and Self-Healing Ionic Gel Electrolyte Based on a Zwitterion (ZI) Copolymer for High-Performance Lithium Metal Batteries

Abstract

Ionic gel electrolyte retains the characteristics of non-volatilization, non-flammability and outstanding electrochemical stability of ionic liquid, and shows good electrochemical performance combined with the excellent characteristics of different matrix materials, which is considered to be the best choice to achieve high energy density and safety at the same time. In this paper, a flexible and self-healing ionic gel electrolyte was prepared using a solvent-assisted method based on a zteric ion (ZI) copolymer. Abundant hydrogen bonds and synergistic interaction of ions in the electrolyte system endowed it with remarkable self-healing ability. An ionic conductivity of 9.06 × 10−4 S cm−1 at room temperature was achieved. Moreover, the lithium-ion transference number was increased to 0.312. The ionic gel electrolyte has a self-healing function which guarantees long-term tolerance during charging and discharging. The capacity retention rate of the Li//LiFePO4 battery was 96% after 155 cycles at 0.1 C at 60 °C. This polymer electrolyte is expected to solve the problem of increasing polarization, which is caused by the low lithium ions migration number in ionic liquid electrolyte. And ultimately, it gave rise to a good rate performance.

Keywords

• flexible electrolyte
• flame-retardant
• self-healing
• gel electrolyte
• lithium metal batteries