Tris(pentafluorophenyl) borane (TPFPB) is evaluated as an additive for improving electrochemical performance of lithium peroxide (Li2O2)-based electrodes. It is found that TPFPB significantly reduced the charge potential of Li2O2-based electrodes during the first charge process and improved reversible capacity during cycling without adding air (or O2) to the cell. To confirm the effect of TPFPB on electrolyte decomposition, the surface chemistry of Li2O2-based electrodes cycled in electrolytes with and without TPFPB was investigated.