In situ fabrication of porous graphene electrodes for high-performance lithium–oxygen batteries

These years, Li–O₂ batteries attract wide interest because of its high theoretical energy density. However, the catalytic activity and porous structure of cathode remains a great challenge. In this work, we developed a hierarchical porous graphene foam to serve as a battery cathode, which has much richer active sites for cathodic reaction and channels for Li⁺ transfer and O₂ diffusion. The cathode exhibits a superior specific capacity as high as 9559 mAh g⁻¹ at 57 mA g⁻¹ and remains a high-rate capability of 3988 mAh g⁻¹ at an increased current density of 285 mA g⁻¹. Benefiting from the well-designed cathode structure, the battery can be stably operated for 150 cycles with a stable voltage profile and voltage efficiency up to 65%. The well-designed graphene has a potential to be a superior free-standing cathode to other carbon-based materials due to its good combination of its hierarchical and porous structure, large surface area, abundant defects and excellent mechanical stability.