High-Performance Lithium-Oxygen Batteries Using a Urea-Based Electrolyte with Kinetically Favorable One-Electron Li2O2 Oxidation Pathways

Glymes are the most widely used electrolyte solvents in lithium-oxygen batteries (LOBs) due to their relatively high stability. However, their associated LOBs have long been plagued by large charge overpotential, which is closely related to the sluggish two-electron Li2O2 oxidation mechanism. Here, we report a new electrolyte solvent-1,1,3,3-tetramethylurea (TMU) for LOBs with high performance and an alternative mechanism, where a kinetically favorable one-electron Li2O2 oxidation pathway can happen in the urea electrolyte system, thus leading to a much lower charge overpotential (approximate to 0.51 V) compared to the tetraglyme-based LOBs (approximate to 1.27 V). Besides, TMU also exhibits good stability since it does not contain any alpha-hydrogen atoms that are vulnerable to be attacked by superoxide species, thus suppressing the hydrogen abstraction side reactions. Consequently, the TMU-based LOBs can stably work for more than 135 cycles, which is four times that of the tetraglyme-based LOBs (approximate to 28 cycles).