Solid State Formation Mechanism of Li4Ti5O12 from an Anatase TiO2 Source

详细信息    查看全文

• 作者：Yanbin Shen ; Martin S酶ndergaard ; Mogens Christensen ; Steinar Birgisson ; Bo B. Iversen
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：June 24, 2014
• 年：2014
• 卷：26
• 期：12
• 页码：3679-3686
• 全文大小：762K
• ISSN：1520-5002

文摘

Solid state synthesis of Li<sub>4sub>Ti<sub>5sub>O<sub>12sub> anode material for Li ion batteries typically results in products containing rutile TiO<sub>2sub> and Li<sub>2sub>TiO<sub>3sub> impurities, and subsequent high calcination temperatures lead to particle growth that reduces capacity and rate ability. Here, the formation and growth of Li<sub>4sub>Ti<sub>5sub>O<sub>12sub> particles by a solid-state reaction using anatase TiO<sub>2sub> with various crystallite sizes and Li<sub>2sub>CO<sub>3sub> is investigated by in situ high temperature powder X-ray diffraction (HT-PXRD) and thermal gravimetry-differential thermal analysis (TG-DTA). The combined data provide insight into the origin of the impurity phases and reveal that formation of Li<sub>4sub>Ti<sub>5sub>O<sub>12sub> from anatase TiO<sub>2sub> and Li<sub>2sub>CO<sub>3sub> is a two stage process. Initially, TiO<sub>2sub> and Li<sub>2sub>CO<sub>3sub> react to form monoclinic Li<sub>2sub>TiO<sub>3sub>, followed at higher temperature by a reaction with the remaining TiO<sub>2sub> to yield Li<sub>4sub>Ti<sub>5sub>O<sub>12sub>. Four anatase TiO<sub>2sub> powders with different crystallite sizes (50 nm, 30 nm, 20 nm, and amorphous) were explored, and decreasing crystallite sizes causes a reduced initial reaction temperature. Using anatase with a crystallite size of 20 nm resulted in phase pure Li<sub>4sub>Ti<sub>5sub>O<sub>12sub> at the lowest temperature (800 掳C). PXRD and TG-DTA results also revealed that Li<sub>4sub>Ti<sub>5sub>O<sub>12sub> decomposes to some Ti rich phases and probably Li<sub>2sub>O when heated above 1000 掳C.