Decoupling mass transport and electron transfer by a double-cathode structure of a Li-O2 battery with high cyclic stability

Aprotic lithium-oxygen (Li-O2) batteries have attracted extensive attention due to their ultrahigh theoretical energy density. However, slow and undesired electron transfer during cathodic reactions causes low cyclic stability in these batteries. Here, we demonstrate that O2 mass transport and electron transfer for cathodic reactions in Li-O2 batteries could be decoupled by a double-cathode structure that efficiently enables stable electron transfer between the cathode and Li2O2/O2. This resolves various side reactions and slow Li2O2 reaction kinetics issues in conventional Li-O2 batteries, leading to stable operation of the cell for nearly 2 months at a capacity of 0.2 and 5 mAh cm−2, with more than 4- and 10-fold increases in cycle life when compared with single-cathode batteries. These remarkable improvements in the cyclic stability of Li-O2 batteries with double cathodes provide an interesting concept for improving the operational stability of other metal-rechargeable batteries with conversion-type chemistry.