Hierarchically porous honeycomb-like carbon as a lithium–oxygen electrode

In this work, hierarchically porous honeycomb-like carbon (HCC) was prepared and used in the fabrication of the air electrode for lithium–oxygen batteries. The HCC-based electrode was found to yield an obviously higher specific capacity of 3233 mA h g−1 without the addition of catalysts and an improved cycle efficiency with a higher discharge voltage plateau (2.75 V vs. 2.50 V) than conventional carbon. The enhanced performance is largely ascribed to its unique porous structure, which consists of large tunnels for oxygen diffusion into the inner electrode and nanosized pores, which serve as reactive sites for oxygen reduction reactions and provide more room for accumulation of deposits. Furthermore, HCC samples with different pore sizes of 400 and 100 nm were investigated in lithium–oxygen batteries. There is a significant relationship between the discharge performance and the diameter.