Ionic liquid enhanced composite solid electrolyte for high-temperature/long-life/dendrite-free lithium metal batteries

Abstract

The composite solid electrolytes (CSEs) inherits the high safety of the inorganic solid electrolyte and the easy processing of the organic polymer electrolyte, thereby exhibiting a broad application prospect. However, the performance of the CSE was hard to realizing its practical application in lithium metal batteries. Herein, the significant impact of CSE performance brought about by the addition of ionic liquids was studied and summarized: significantly increase ionic conductivity; constructing a viscoelastic interface between electrode and electrolyte to reduce the interface impedance; forming a stable and LiF-rich SEI at the negative electrode to inhibit the growth of lithium dendrites; wetting the LiFePO4 porous cathode. The LiFePO4/CSE-60/Li battery displays high initial discharge specific capacity of 158.2 mAh g−1 and a capacity retention of 86.3% after 400 cycles at 1 C at 55 °C, and with coulombic efficiency of 99.7%. The surface of the lithium metal anode after long-term cycling exhibits to dendrite-free morphology. This research highlights the critical role that ionic liquids play in improving the performance of CSEs and will shed light on designing CSEs for LMB practical applications.