Improved Li-ion diffusion process in TiO2/rGO anode for lithium-ion battery

[摘要] The low diffusion rate of pure TiO2 affects the inferior electrochemical performance such as cycling capacity and rate capability. Many works have been focusing on the material structural control to solve this problem, but the specific mechanism of the electrochemical process still needs further study. In this paper, we prepare titanium dioxide/reduced graphene oxide (TiO2/rGO) hybrids to comprehend the improved diffusion rate by using electrochemical kinetics characterization. Compared with pure TiO2, the TiO2/rGO hybrids have a reduced particle size and layer-shaped structure. For electrochemical test, the TiO2/rGO assembly exhibits high rate capability (similar to 270 mAh g(-1) at 0.1 A g(-1)), and excellent cycling capacity (similar to 180 mAh g(-1) at 0.5 A g(-1) after 2000 cycle). Studying the electrochemical reaction process finds that the charge transfer rate of titanium oxide were significantly increased due to the addition of graphene oxide. A diffusion controlled behavior of Li+ is found to dominate the charge-discharge process in TiO2/rGO hybrids, rather than the capacitive process of the pure TiO2 electrode. This dominated diffusion is believed to inspire both of superior rate and capacity of the TiO2/rGO hybrids in this work. (C) 2017 Elsevier B.V. All rights reserved.

[发布日期] 2017-12-15

[关键词] Kinetics;Electrochemical performance;TiO2/rGO;Diffusion coefficient;Li-ion batteries