Three-dimensional hierarchical wreath-like Co3O4@ TiO2 as an anode for lithium-ion batteries

Abstract

Abstract Wreath-like Co3O4 particles consisting of microplates are synthesized by a facile solvothermal method and subsequently surface-modified with TiO2 ultrathin layer using a low-temperature hydrolysis process. Comparing with pure Co3O4, Co3O4@TiO2 exhibits superior electrochemical performances in terms of reversible capacity, rate capability and cycling stability. Co3O4@TiO2 exhibits high reversible capacity of 813.0\u202fmAhg−1 at 500\u202fmAg−1 after 180 cycles while the pristine Co3O4 only has a discharge capacity of 512.5\u202fmAhg−1. The filling of TiO2 nanoparticles in porous Co3O4 sheets and the TiO2-coating on Co3O4 surface, could effectively suppress large volume expansion of Co3O4 and consequently enhance structural stability during the Li-ion insertion/extraction processes. Analysis from the electrochemical measurements reveals that the improved performances should be attributed to reduced the charge-transfer resistance and enhanced Li-ion diffusion kinetics because of TiO2-coating. In addition, the reduced work function induced by TiO2-coating is helpful to facilitate electron transfer in composites. Moreover, the built-in electric field resulting from the difference in work function between Co3O4 and TiO2, would facilitate electron-transfer and Li-ion migration across heterojunction interfaces.