Co3O4 modified Ag/g-C3N4 composite as a bifunctional cathode for lithium-oxygen battery

Rechargeable lithium-oxygen（Li-O）batteries have appeal to enormous attention because they demonstrate higher energy density than the state-of-the-art Li-ion batteries.Whereas,their practical application is impeded by several challenging problems,such as the low energy round trip efficiencies and the insufficient cycle life,due to the cathode passivation caused by the accumulation of discharge products.Developing efficient catalyst for oxygen reduction and evolution reactions is effective to reduce the overpotentials in Li-Ocells.In our work,we report a CoOmodified Ag/g-CNnanocomposite as a bifunctional cathode catalyst for Li-Ocells.The g-CNsubstrate prevents the accumulation of Ag and CoOnanoparticles and the presence of Ag NPs improves the surface area of g-CNand electronic conductivity,significantly improving the oxygen reduction/evolution capabilities of CoO.Due to a synergetic effect,the Ag/g-CN/CoOnanocomposite demonstrates a higher catalytic activity than each individual constituent of CoOor Ag/g-CNfor the ORR/OER on as catalysts in Li-Ocells.As a result,the Ag/gCN/CoOcomposite shows impressive electrochemical performance in a Li-Obattery,including high discharge capacity,small gap between charge and discharge potential,and high cycling stability.