Abstract
Large energy-storage systems and electric vehicles require energy devices with high power and high energy density. Lithium oxygen (Li-O-2) batteries could achieve high energy density, but they are still facing problems such as low practical capacity and poor cyclability. Here, we prepare activated carbons (MGACs) based on the natural plant Miscanthus x giganteus (MG) through slow pyrolysis. It possesses a large surface area, plenty of active sites, and high porosity, which are beneficial to the utilization of oxygen electrode in Li-O-2 batteries. The MGACs-based oxygen electrode delivers a high specific capacity of 9400 mAh/g at 0.02 mA/cm(2), and long cycle life of 601 cycles (with a cutoff capacity of 500 mAh/g) and 295 cycles (with a cutoff capacity of 1000 mAh/g) at 0.2 mA/cm(2), respectively. Additionally, the material exhibits high rate capability and high reversibility, which is a promising candidate for the application in Li-O-2 batteries.