Fabrication of TiO2 coated porous CoMn2O4 submicrospheres for advanced lithium-ion anodes

Abstract

Herein, a facile and general way for the synthesis of TiO2 coated cobalt manganese oxide CoMn2O4 (CMO) has been developed. In this contribution, uniform Co0.33Mn0.67CO3 spheres are firstly fabricated via a solvothermal method. Porous CMO with a diameter of about 800 nm is obtained by a subsequent annealing procedure. Finally, a thin layer of TiO2 is coated on the surface of the CMO through a hydrolysis and subsequent condensation process. When evaluated as anode materials for lithium ion batteries (LIBs), after 500 cycles at a current density of 1000 mA g−1, the CMO@TiO2 spheres possessed high reversible capacities of 940 mA h g−1 with a suitable discharge plateau of ∼0.6 V, much higher than the pristine CMO. In addition, the CMO@TiO2 shows better rate performance than CMO, as high as 196 mA h g−1 at a very fast discharge current of 5 A g−1. The high electrochemical performance of CMO@TiO2 should be attributed to its special structure of nanometer scale spheres with high porosity and the thin layer coating of TiO2 as a zero-strain shell, which can effectively reduce the diffusion length of electrolyte, Li+ and electrons, buffer volume expansion during the Li+ insertion/extraction processes and thus reduce the materials' pulverization.