Supramolecular Network Structured Gel Polymer Electrolyte with High Ionic Conductivity for Lithium Metal Batteries

Polymer-based solid electrolytes (PSEs) offer great promise in developing lithium metal batteries due to their attractive features such as safety, light weight, low cost, and high processability. However, a PSE-based lithium battery usually requires a relatively high temperature (60 °C or above) to complete charge and discharge due to the poor ionic conductivity of PSEs. Herein, a gel polymer electrolytes (GPEs) film with a supramolecular network structure through a facile one-step photopolymerization is designed and developed. The crosslinked structure and quadruple hydrogen bonding fulfil the GPEs with high thermal stability and good mechanical property with a maximum tensile strain of 48%. The obtained GPEs possess a high ionic conductivity of 3.8 × 10^-3 S cm^-1 at 25 °C and a decomposition voltage ≥ 4.6 V (vs Li/Li⁺ ). The cells assembled with LiFePO₄ cathode and Li anode, present an initial discharge specific capacity of 155.6 mAh g^-1 and a good cycling efficiency with a capacity retention rate of 81.1% after 100 charges/discharge cycles at 0.1 C at ambient temperature. This work encompasses a route to develop high performance PSEs that can be operated at room temperature for future lithium metal batteries.