We find that the Li-O2 cell with a MWCNTs electrode in a 0.7 M LiNO3-0.3 M LiTFSI/ DMSO electrolyte demonstrates good rate performance and cycle stability comparison with other carbon electrodes. The result shows that the Li-O2 cell based on MWCNTs electrodes with a cut-off capacity of 1000 mAg-1 at 500 mAg-1 can undergo around 90 cycles without obvious capacity loss. Even when the discharge depth is increased to 2000 mAhg-1, stable cycling is maintained for 45 cycles with a charge potential below 4.0 V vs. Li/Li+. Moreover, when the rate performance of Li-O2 cell with MWCNTs electrodes is examined at different current densities from 200, 400, 500, and 1000 mAg-1 with a cut-off capacity of 2000 mAhg-1, interestingly, the discharge voltage is not drastically increased even the current density is 1000 mAg-1. And then, the chare voltage remains at around 3.85 V, which is similar to the current density of 200 mAg-1 (about 3.82 V). Therefore, these results demonstrate that the MWCNTs maintain excellent activity and stability of catalysts toward the reversible formation-decomposition of Li2O2.
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