Three-dimensional self-standing Co@NC octahedron/biochar cathode for non-aqueous Li-O2 batteries: efficient catalysis for reversible formation and decomposition of LiOH

Lithium–oxygen (Li-O2) batteries have received wide attention due to their high specific capacity. In non-aqueous Li-O2 batteries, water is generally considered as a harmful pollutant, which will cause parasitic reaction to generate LiOH. However, it is difficult to decompose in the charging process, resulting in premature failure of battery and serious impact on the cycle stability. Therefore, it is of great significance to explore efficient catalysts to decompose LiOH for the future commercialization of Li-air batteries. In this work, a novel three-dimensional (3D) self-standing Co@NC octahedron/biochar is used as the cathode of Li-O2 battery. Ex situ XRD and XPS identify that the discharge products were LiOH rather than Li2O2. However, the specific capacity of Li-O2 battery with Co@NC still reaches up to 14.1 mAh cm-2 at a current density of 0.1 mA cm-2 and sustains a stable cycling of 136 times with a limited capacity of 0.5 mAh cm−2 at 0.1 mA cm−2. It is found that the charge specific capacity of the battery with preloading LiOH in the cathode is close to the actual theoretical value, proving that Co@NC could effectively decompose LiOH.