Influence of carbon surface on the discharge voltage of non-aqueous Li-O2 battery was investigated. The discharge voltage definitely decreased with the graphitization of as-prepared carbon in spite of almost the same chemical information of carbon surface. Graphitization of carbon led to the dramatic morphological change from granular-type to angulated-type, and as a consequence, the number of defect part toward basal part was decreased. The defect parts of the carbon surface were suggested to promote the Li+ containing oxygen reduction reaction (Li+-ORR) related with the discharge voltage. Cyclic voltammetry indicated that the ORR potential in the Li+ containing media was positively shifted on the edge oriented carbon model plane, compared with those of the graphitized ones. It was, thus, concluded that the carbon surface including defects activated the Li+-ORR process on a cathode, resulting in the increase of discharge voltage.
2012 The Electrochemical Society of Japan