| Abstract: | Li‐O2 batteries are promising candidates for next‐generation high‐energy‐density battery systems. However, the main problems of Li–O2 batteries include the poor rate capability of the cathode and the instability of the Li anode. Herein, an ester‐based liquid additive, 2,2,2‐trichloroethyl chloroformate, was introduced into the conventional electrolyte of a Li–O2 battery. Versatile effects of this additive on the oxygen cathode and the Li metal anode became evident. The Li–O2 battery showed an outstanding rate capability of 2005 mAh g?1 with a remarkably decreased charge potential at a large current density of 1000 mA g?1. The positive effect of the halide ester on the rate capacity is associated with the improved solubility of Li2O2 in the electrolyte and the increased diffusion rate of O2. Furthermore, the ester promotes the formation of a solid–electrolyte interphase layer on the surface of the Li metal, which restrains the loss and volume change of the Li electrode during stripping and plating, thereby achieving a cycling stability over 900 h and a Li capacity utilization of up to 10 mAh cm?2. |
