Hierarchical Graphene-Rich Carbon Materials with Trace Nonprecious Metals for High-Performance Li-O2 Batteries

Sluggish kinetic characteristics of the electrode reactions and low electrode space utilization for solid Li2O2 deposition are limiting factors for Li-O-2 batteries. In this work, iron-/cobalt-doped micron-sized honeycomb-like carbon (Fe-MHC, Co-MHC) with a hierarchical pore structure is prepared by using nano-CaCO3 as a template. The effect of the transition-metal nanoparticles as a second template on further pore construction and optimization is presented. As graphitization catalysts, the added transition metals also affect the formation of the graphene-rich structure in the carbon framework. As a result, the obtained hierarchical carbon materials doped with trace metals exhibit higher electrochemical catalytic activity and stability than non-doped samples. In particular, an enhanced discharge capacity as high as 9260 mAhg(-1) is achieved for the Fe-MHC cathode, which is attributed to its enlarged pore volume and high utilization of the electrode space.