A novel flame-retardant nitrile-based gel polymer electrolyte for quasi-solid-state lithium metal batteries

In this work, a novel type of highly Li+-ions conductive, nonflammable adiponitrile (ADN)-based gel polymer electrolyte (denoted as AT11-GF) was prepared as a promising solid-state electrolyte for lithium (Li)-metal batteries by in-situ polymerization method. In order to overcome the parasitic reactions of ADN and triethyl phosphate (TEP) on Li-anode surface, fluoroethylene carbonate (FEC) was utilized as film-forming agent to generate LiF-enrich interface in this system of ADN-based electrolyte. The as-prepared electrolyte exhibited high ionic conductivity of 1.724 × 10−3 S/cm at ambient temperature, wide electrochemical window (∼5.75 V vs. Li+/Li), favorable Li+-ion transfer number (tLi+=0.70), and superior interfacial compatibility with Li anode (ultra-stable at a current density of 0.2 mA/cm2 for 1000 h). The LiFePO4|AT11-GF|Li battery presented an excellent rate capacity of 116.9 mAh/g at 2.0 C, and long-term cycling performance with a specific capacity of 134.6 mAh/g and a capacity retention of 94.5% after 1000 cycles at a current density of 1.0 C. Therefore, this as-prepared ADN-based electrolyte exhibited great promise for the application in solid-state Li-metal batteries.