Enhancing Electrochemical Performance of LiMn2O4 Cathode Material at Elevated Temperature by Uniform Nanosized TiO2 Coating

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• 作者：Congcong Zhang ; Xiaoyu Liu ; Qili Su ; Jianhua Wu ; Tao Huang ; Aishui Yu
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：5
• 期：1
• 页码：640-647
• 全文大小：556K
• ISSN：2168-0485

文摘

The severe capacity fading of LiMn₂O₄ at elevated temperature hinders its wide application in lithium ion batteries despite several advantages over present cathode materials in terms of cost, rate capability, and environmental benignity. In this study, porous nanosized TiO₂-coated LiMn₂O₄ is prepared via a modified sol–gel process of controlling hydrolysis and condensation of titanium tetrabutoxide in ethanol/ammonia mixtures, and the phenomenon of homogeneous nucleation has been almost entirely avoided. The X-ray diffraction patterns and transmission electron microscopy images show that a porous nanosized TiO₂ layer is uniformly coated on the surface of spinel LiMn₂O₄. Electrochemical tests reveal that the optimal coating content is 3 wt % which shows remarkably improved capacity retentions at both room temperature of 25 °C and elevated temperature of 55 °C. Even after long-term charge and discharge cycles, the TiO₂ layer is still robust enough to prevent LiMn₂O₄ particles from the attack of electrolyte. The inductively coupled plasma-atomic emission spectrometry, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy results indicate that the obvious improvement of TiO₂-coated LiMn₂O₄ electrodes is attributed to the suppression of Mn dissolution, as well as the enhancement of kinetics of Li⁺ diffusion.