Effect of LiBOB content on electrochemical performance of Li–O2 batteries

Lithium-oxygen batteries show great energy storage potential due to their high energy density. However, it is difficult for conventional liquid electrolytes to form a stable solid electrolyte interface (SEI) on cathode surface to ensure long-term stable cycling of lithium-oxygen batteries. Herein, LiBOB is added to the LiTFSI-based electrolyte to solve the above-mentioned problems. By introducing LiBOB into LiTFSI single-salt electrolyte system, the electron delocalization of the BOB− anion induces the dissociation equilibrium of the lithium salt to occur positively and the formed electrolyte exhibits good ionic conductivity. Different amounts of LiBOB show different characteristics in electrochemical performance. Trace amounts of LiBOB as an additive increase the solvation of Li+ and improve the discharge capacity of the cell. Furthermore, the synergistic effect of the LiTFSI-LiBOB dual-salt electrolyte forms a protective SEI when LiBOB has a larger proportion of lithium salts in the electrolyte, resulting in comparable cycling performance. This work demonstrates a promising approach to design electrolytes for long-term stable cycling of lithium-oxygen batteries.