Iongel Soft Solid Electrolytes Based on [DEME][TFSI] Ionic Liquid for Low Polarization Lithium-O2 Batteries

Abstract

Lithium-air/O2 batteries are a promising battery technology for automotive applications due to their high energy density. However, many challenges need to be solved, particularly the high reactivity of the electrolyte with oxygen superoxide radicals and its low cyclability. In this work, we present a simple and fast way to prepare polymer-based iongel soft solid electrolytes. Thermally and mechanically stable iongels are prepared by fast UV-photopolymerisation exhibiting a high ionic conductivity (∼1.2×10−3 S cm−1 at 25 °C). When used as solid electrolytes in lithium symmetrical cells, they can withstand a critical current density of 0.5 mA cm−2. Performance in Li−O2 cells showed capacities as large as 3.3 mAh cm−2, and cycling capability of 25 cycles, exceeding results on liquid-counterpart cells.