Two-step method to synthesize spinel Co3O4-MnCo2O4 with excellent performance for lithium ion batteries

Spinel Co3O4-MnCo2O4 was synthesized by a two-step method, with a post annealing step after loading MnO2 on the surface of Co-MOF (ZIF-67). For the first step, the methyl (-CH3) groups of ZIF-67 were oxidized to carboxyl (-COOH) groups, with MnO2 uniformly loaded on ZIF-67. Benefiting from this step, the uniform distribution of spinel Co3O4-MnCo2O4 was achieved after calcination. Based on the stable framework of Co-MOF, a nanoparticle spinel Co3O4-MnCo2O4 was obtained with an average diameter of 20-50 nm. This nano-sized characteristic not only shortens the diffusion lengths of lithium ion, but also alleviates the volume expansion of material during the Li+ insertion/extraction process. The as-synthesized spinel Co3O4-MnCo2O4 exhibited superior rate stability and cycle stability with high energy density and power density. Even at 5000 mA g(-1), a specific capacity of 614 mA h g(-1) can be maintained. In view of the remarkable performance of spinel Co3O4-MnCo2O4, it can be concluded that spinel Co3O4-MnCo2O4 has a potential to be an anode material in LIBs. Further, this two-step method can be used to prepare other mixed transition-metal oxides in various fields.