CxNy particles@N-doped porous graphene: a novel cathode catalyst with a remarkable cyclability for Li–O2 batteries

Abstract

Despite the intrinsic advantages of ultra-high theoretical capacity and energy density of lithium–O₂ batteries, there remain several critical issues to be resolved, especially the two concerning poor cyclability and rate capability. In this work, C_xN_y particles@N-doped porous graphene (C_xN_y@NPG) with a novel three-dimensional architecture is successfully synthesized via a simple template method and employed as the cathode catalyst of Li–O₂ batteries. It is surprisingly found that the as-synthesized C_xN_y@NPG cathode not only demonstrates a remarkable cycling performance of 200 cycles at 1000 mA g⁻¹ but also an intriguing high-rate capability with 8892 mA h g⁻¹ at 1000 mA g⁻¹, both of which can be attributed to a synergistic effect between the unique 3D porous structure and an effective N-doping. Specifically, it is believed that the unique porous 3D structure will, on one hand, build numerous microchannels, thus facilitating rapid O₂ diffusion, and on the other hand, provide sufficient storage space to accommodate adequate discharge products. Indispensably, it is also believed that the N-doped porous graphene enables improved bifunctional catalytic activities towards both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), thus decreasing the discharge/charge overpotential, and reducing undesired side reactions. It is anticipated that the new 3D porous C_xN_y@NPG provides an inspiring route to design long cycling and high-rate performance cathodes for Li–O₂ batteries.