PNNL

Abstract

Extended cycling of the Li-O2 battery under full discharge/charge conditions is achievable upon selection of appropriate electrode materials and cycling protocol. However, the decomposition of the side products also contribute to the observed good cycling behavior of high capacity Li-O2 batteries. Quantitative analyses of the discharge and charge products reveals a quick switch from the predominant formation of Li2O2 to the predominant formation of side products during the first a few cycles of the Li-O2 batteries. After the switch, cycling stabilizes with a repeatable formation of Li2O2/side products at ~1:2 ratio. CNTs/Ru composite electrodes exhibits lower charge voltage and deliver 50 full discharge-charge cycles without sharp capacity drop. Ru coated glass carbon electrode can lead to more than 500 cycles without change in its cycling profiles. The better understanding on Li-O2 reaction processes developed in this work may lead to the further improvement on the long term cycling behavior of high capacity Li-O2 batteries.