Recent progress in liquid electrolytes for lithium metal batteries

Abstract Li metal batteries are revived as the next-generation batteries beyond Li-ion batteries. The Li metal anode can be paired with intercalation-type cathodes LiMO2 and conversion-type cathodes such as sulfur and oxygen. Then, energy densities of Li/LiMO2 and Li/S,O2 batteries can reach 400 Whkg−1 and more than 500 Whkg−1, respectively, which surpass that of the state-of-the-art LIB (280 Whkg−1). However, replacing the intercalation-type graphite anode with the Li metal anode suffers from low coulombic efficiency during repeated Li plating/stripping processes, which leads to short cycle lifetime and potential safety problems. The key solution is to construct a stable and uniform solid electrolyte interphase with high Li+ transport and high elastic strength on the Li metal anode. This review summarizes recent progress in improving the solid electrolyte interphase by tailoring liquid electrolytes, a classical but the most convenient and cost-effective strategy.