Functionalized graphene assisted the formation of mesocarbon microbeads with ultra-large size and loose microcrystalline structure from petroleum pitch for sodium-ion batteries anode

It is a significant way to improve the sodium storage performance of mesocarbon microbeads (MCMBs) by adjusting the size and microcrystalline structure of it. A petroleum-based MCMBs with an ultra-large size and loose microcrystalline structure was synthesized by introducing functionalized graphene (FNG). The results indicate that the FNG can hinder the ordered stacking of planar aromatic macromolecules, prevent the coalescence and prolong the growth time of mesophase spheres. Mesophase spheres are easier to grow to an ultra-large size with looser microcrystalline structure. The MCMBs with a size of 250 µm and a larger microcrystalline spacing can be achieved by adding 1.0 wt% FNG during the polycondensation process. Such MCMBs deliver a competitive specific capacity of 123.4 mAh g−1 at a current density of 1.0 A g−1 with a high initial coulombic efficiency of 81.79% and an excellent stability of cycle performance when applied as anode of SIBs. This work provides a valuable and efficient method to enhance the SIB performance by designing the size and microcrystalline structure of MCMBs.