Bioinspired gel polymer electrolyte for wide temperature lithium metal battery
Shuohan Liu, Wensheng Tian, Jieqing Shen, Zhikai Wang, Pan Hui, Xuchen Kuang, Cheng Yang, Shunwei Chen, Xiujun Han, Hengdao Quan, Shenmin Zhu
Abstract
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. Lithium-metal batteries struggle in extreme environments, restricting their applications. Here, authors report a bioinspired gel polymer electrolyte that employs double dipole coupling to form a weak solvation structure, enabling stable operation of lithium-metal batteries from −30 to 80 °C.