Carbon-Enhanced Electrochemical Performance for Spinel Li5Cr7Ti6O25 as a Lithium Host Material

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• 作者：Lei Yan ; Shangshu Qian ; Haoxiang Yu ; Peng Li ; Hua Lan ; Nengbing Long ; Ruifeng Zhang ; Miao Shui ; Jie Shu
• 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：957-964
• 全文大小：695K
• ISSN：2168-0485

文摘

The design and facile fabrication of CrTi-based anode materials with long-life, good safety, and low cost are strongly desired for lithium-ion batteries. In this study, we adopt the sol–gel method using glucose as carbon source to synthesize carbon-coated Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>. The effects of a carbon layer in Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>/C on electrochemical properties are focused through comparing carbon-coated Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub> with carbon-free Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>. Electrochemical tests show that Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>/C possesses better cycling and rate performances than those of carbon-free Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>. Cycled at 500 mA g<sup>–1sup>, Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>/C delivers a high specific capacity of 111.6 mAh g<sup>–1sup> with 13% capacity loss after 200 cycles. In contrast, Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub> only exhibits a specific capacity of 93.6 mAh g<sup>–1sup> at 500 mA g<sup>–1sup> with 19% capacity loss after 200 cycles. The preeminent electrochemical property of Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>/C is ascribed to the amorphous carbon coating layer. This carbon layer can remarkably facilitate the transportation of electrons and ions in Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>. Furthermore, the lithiation/delithiation behavior of Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>/C is also investigated by advanced in situ X-ray diffraction technique, and the results verify that Li<sub>5sub>Cr<sub>7sub>Ti<sub>6sub>O<sub>25sub>/C possesses a highly reversible structural change during the charge/discharge process.