Bioinspired gel polymer electrolyte for wide temperature lithium metal battery

Stable operation of Li metal batteries with gel polymer electrolytes in a wide temperature range is highly expected. However, insufficient dynamics of ion transport and unstable electrolyte-electrode interfaces at extreme temperatures greatly hinder their practical applications. We report a bioinspired gel polymer electrolyte that enables high-energy-density Li metal batteries to work stably in a wide temperature range from –30 to 80 °C. The wide-temperature gel polymer electrolyte is fabricated by using a branched polymer of which side chains are double coupled with their asymmetric analogues. The double dipole coupling regulates the Li+ coordination environment to form a weak solvation structure that offers fast and uniform Li+ deposition at extreme temperatures. Consequently, the non-flammable gel polymer electrolyte displays an ionic conductivity of 1.03 × 10–4 S cm−1 at –40 °C and a Li+ transference number of 0.83. The Li metal batteries with LiNi0.8Co0.1Mn0.1O2 positive electrode deliver initial specific discharge capacities of 121.4 mAh g–1 at –30 °C and 172.2 mAh g–1 at 80 °C, with corresponding discharge currents of 18.8 mA g–1 and 188 mA g–1, respectively. Additionally, a pouch cell delivers a specific energy up to 490.8 Wh kg−1.