Maximal Utilization of a High-Loading Cathode in Li-O2 Batteries: A Double Oxygen Supply System.

To realize the potential high capacity of lithium-oxygen (Li-O2) batteries, a double oxygen supply system for cells with high-loading cathodes is devised in this study. High-loading thick electrodes can achieve exceptionally high capacities, but this promise has been plagued by partial utilization of thick electrodes in Li-O2 cells due to the kinetic limitation imposed by oxygen transport. The proposed double oxygen supply system provides oxygen gas to the cathode not only from the cathode opening but also from the separator side to ensure sufficient oxygen supply to the whole high-loading electrode. Subsequently, the entire region of the high-loading cathode is rendered active, resulting in a uniform vertical distribution of discharge products. The maximum utilization of the high-loading electrodes is, thus, achieved, along with a remarkably increased capacity, low overpotential, and cycle life. By this strategy, CNT cathodes can be cycled with a capacity of 5 mAh cm-2, without using any additional catalyst.