A superhigh discharge capacity induced by a synergetic effect between high-surface-area carbons and a carbon paper current collector in a lithium–oxygen battery *Project supported by the Natural Science Foundation of the Chinese Academy of Sciences (Grant No. KGZD-EW-202-2), the National Key Basic Research Program of China (Grant No. 2014CB921004), and the National Natural Science Foundation of China (Grant No. U1232111). (August 2015) - Luo, Guang-Sheng
Abstract This paper invesitages the synergetic effect between high-surface-area carbons, such as Ketjan Black (KB) or Super P (SP) carbon materials, and low-surface-area carbon paper (CP) current collectors and it also examines their influence on the discharge performance of nonaqueous Li–O2 cells. Ultra-large specific discharge capacities are found in the KB/CP cathodes, which are much greater than those observed in the individual KB or CP cathodes. Detailed analysis indicates that such unexpectedly large capacities result from the synergetic effect between the two components. During the initial discharges of KB or SP materials, a large number of superoxide radical species in the electrolytes and Li2O2 nuclei at the CP surfaces are formed, which activate the CP current collectors to contribute considerable capacities. These results imply that CP could be a superior material for current collectors in terms of its contribution to the overall discharge capacity. On the other hand, we should be careful to calculate the specific capacities of the oxygen cathodes when using CP as a current collector; i.e., ignoring the contribution from the CP may cause overstated discharge capacities.