The reaction mechanism of the Mg2+ and F⿿ co-modification and its influence on the electrochemical performance of the Li4Ti5O12 anode material. (10th January 2016)

• Record Type: Journal Article
• Authors: Li, Wen; Wang, Hao; Chen, Mianzhong; Gao, Jingjing; Li, Xiang; Ge, Wujie; Qu, Meizhen; Wei, Aijia; Zhang, Lihui; Liu, ZhenFa
• Is Part Of: Electrochimica acta. Volume 188(2016)
• Page Start: 499
• Page End: 511
• Publication Date: 2016-01-10
• Subjects: Li4Ti5O12 -- MgF2 -- modification -- lithium ion batteries; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2015.11.105
• Languages: English
• ISSNs: 0013-4686

Abstract

Graphical abstract: After the modification process, F ⿿ reacts with LTO chemically to generate new impurity phase such as anatase TiO2, rutile TiO2 and LiF, while Mg 2+ forms MgO coating layer on the Li4 Ti5 O12 particles. The 1 wt% Mg 2+ and F ⿿ co-modified Li4 Ti5 O12 has a higher capacity than commercial Li4 Ti5 O12 at different C-rates in the range of 0 ⿼ 3⿿V. The MgO coating layer could prevent the electrolyte reduction decomposition on the Li4 Ti5 O12 particles. Therefore, the cycling performance of the Mg 2+ and F ⿿ co-modified Li4 Ti5 O12 and Mg 2+ modified Li4 Ti5 O12 at a high rate of 5C are greatly improved. Highlights: ⿢ The reaction mechanism of Mg 2+ and F ⿿ co-modification is studied. ⿢ F ⿿ reacts with LTO to form new impurity phase, such as anatase TiO2, rutile TiO2 and LiF. ⿢ Mg 2+ forms a coating layer on the LTO particles. ⿢ 1 wt% Mg 2+ and F ⿿ co-modified LTO exhibits excellent capacity and rate capability. ⿢ The Mg 2+ and F ⿿ co-modified LTO samples also present outstanding cycling performance at a high rate of 5C. Abstract: The commercial Li4 Ti5 O12 is co-modified using Mg 2+ and F ⿿ via a co-precipitation method with the purpose of understanding the reaction mechanism of the fluoride modification process. For comparison, the commercial Li4 Ti5 O12 is also modified using Mg 2+ and F ⿿, respectively. After the co-modification process, F ⿿ reacts with Li4 Ti5 O12 chemically to generate new impurity phase such as anatase TiO2, rutile TiO2 and LiF, while Mg 2+ forms MgO coating layer on the Li4 Ti5 O12 particles. The capacity and rate capability of the Li4 Ti5 O12 have been improved after the 1wt% Mg 2+ and F ⿿ co-modification. The charge capacity of the Mg 2+ and F ⿿ co-modified Li4 Ti5 O12 at 0.5C, 1C, 3C, 5C and 10C rate in the range of 0 ⿼3 V is 234.1, 218.6, 200.8, 182 and 148mAh g ⿿1, respectively. Meanwhile, the electrolyte reduction decomposition on the Li4 Ti5 O12 was suppressed after the co-modification process, thereby enhancing the cycling performance of the Mg 2+ and F ⿿ co-modified Li4 Ti5 O12 . In particular, the 3 wt% Mg 2+ and F ⿿ co-modified Li4 Ti5 O12 keeps 74.5% charge capacity after 200 cycle charge-discharged test at a high rate of 5C, which is higher than the commercial Li4 Ti5 O12 (58.7%).