Synthesis and electrochemical investigation of hollow hierarchical metal oxide microspheres for high performance lithium-ion batteries

In this paper, a versatile facile route to synthesize mesoporous hollow-structured metal oxides is demonstrated using sulfonated polystyrene (SPS) microspheres as hard templates. SEM and TEM images show that the Fe2O3, Co3O4 and NiO hollow microspheres are self-assembled by nanorods, nanoparticles and nanosheets, respectively. Hollow and mesoporous structures not only provide enhanced mechanical stabilities to buffer the large volume changes during the charge/discharge processes, but also provide large specific areas for sufficient penetration of electrolyte, thus leading to an excellent cyclic stability and rate capability. As proofs-of-concepts, all of the hollow and mesoporous metal oxides (Fe2O3, Co3O4 and NiO) deliver high initial discharge capacities and good capacity retentions (>80%) after more than 100 cycles in half cells. Most important of all, these assembled full-cells (MxOy(M = Fe, Co, Ni)/LiCoO2) also delivere excellent electrochemical performances. This work clearly demonstrates that the MxOy(M = Fe, Co, Ni)/LiCoO2 configuration are promising alternative high power-density energy storage devices in the near future.