Dual Lithium Insertion and Conversion Mechanisms in a Titanium-Based Mixed-Anion Nanocomposite

详细信息    查看全文

• 作者：Damien Dambournet ; Karena W. Chapman ; Peter J. Chupas ; Rex E. Gerald ; II ; Nicolas Penin ; Christine Labrugere ; Alain Demourgues ; Alain Tressaud ; Khalil Amine
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：August 31, 2011
• 年：2011
• 卷：133
• 期：34
• 页码：13240-13243
• 全文大小：762K
• 年卷期：v.133,no.34(August 31, 2011)
• ISSN：1520-5126

文摘

The electrochemical reaction of lithium with a vacancy-containing titanium hydroxyfluoride was studied. On the basis of pair distribution function analysis, NMR, and X-ray photoelectron spectroscopy, we propose that the material undergoes partitioning upon initial discharge to form a nanostructured composite containing crystalline Li_xTiO₂, surrounded by a Ti⁰ and LiF layer. The Ti⁰ is reoxidized upon reversible charging to an amorphous TiF₃ phase via a conversion reaction. The crystalline Li_xTiO₂ is involved in an insertion reaction. The resulting composite electrode, Ti⁰-LiF/Li_xTiO₂ TiF₃/ Li_yTiO₂, allows reaction of more than one Li per Ti, providing a route to higher capacities while improving the energy efficiency compared to pure conversion chemistries.