Cerium triflate (Ce(CF3SO3)3) is used as a superoxide radical scavenger in the ether-based liquid electrolyte for the LiO2 batteries. The radical scavenging capability of Ce3+ is evaluated both in potassium superoxide + crown solution and the LiO2 batteries. The chemical analyses further demonstrate cerium ions can effectively slow down the decomposition of electrolyte attacked by superoxide radicals. When the capacity is fixed to 1000 mAh g−1 at a current density of 500 mA g−1, the LiO2 battery with 1M LiTFSI-TEGDME electrolyte begins to drop its discharge voltage rapidly to 2.0 V near 40th cycle while the electrolyte with Ce3+ additives is still above 2.0 V after 88 cycles, demonstrating the cycle life of the LiO2 batteries show remarkably improved compared to the LiO2 batteries without any additive into electrolyte.