Carbonate decomposition: Low-overpotential Li-CO2 battery based on interlayer-confined monodisperse catalyst

The operation of Li-air batteries is currently limited to O2 instead of air, mainly attributed to the formation of wide-bandgap insulator Li2CO3 during discharge caused by the presence of CO2 in air. A thorough understanding of the decomposition mechanism of Li2CO3 is crucial but challenging owing to the existence of side reactions induced by the large charge overpotential. Here, monodisperse RuO2 supported on layered double oxide is utilized as cathodes for Li-CO2 batteries with ultralow charge overpotential (only ~0.4 V larger than equilibrium potential, 2.80 V). The reversibility of Li-CO2 battery is mainly attributed to the decomposition of Li2CO3 upon charging instead of the degradation of the electrolyte. These results advance the fundamental understanding of the carbonate decomposition in Li-CO2 batteries and offer a promising route to utilizing agglomeration of layered-confined monodisperse catalyst to enlarge the layered spacings of layered support with complementary catalytic activity for Li-CO2 batteries with high energy efficiency and superior cycle life.