Lithium Salt Dissociation Promoted by 18-Crown-6 Ether Additive toward Dilute Electrolytes for High Performance Lithium Oxygen Batteries.

Lithium-oxygen batteries (LOBs) are well known for their high energy density. However, their reversibility and rate performance are challenged due to the sluggish oxygen reduction/evolution reactions (ORR/OER) kinetics, serious side reactions and uncontrollable Li dendrite growth. The electrolyte plays a key role in transport of Li + and reactive oxygen species in LOBs. Here, we tailored a dilute electrolyte by screening suitable crown ether additives to promote lithium salt dissociation and Li + solvation through electrostatic interaction. The electrolyte containing 100 mM 18-crown-6 ether (100-18C6) exhibits enhanced electrochemical stability and triggers a solution-mediated Li 2 O 2 growth pathway in LOBs, showing high discharge capacity of 10 828.8 mAh g carbon -1 . Moreover, optimized electrode/electrolyte interfaces promote ORR/OER kinetics on cathode and achieve dendrite-free Li anode, which enhances the cycle life. This work casts new lights on the design of low-cost dilute electrolytes for high performance LOBs.