Ti4O7/C复合纳米纤维的可控制备及电化学性能研究

Magneli phase Ti4O7 is an extremely promising ceramic electrode material, which is placed in great expectations in the solution to the energy crisis problems. However, its practical applications is subject to certain restrictions of large in particle size, difficult to control the morphology and low specific surface area. Applicants have proposed that Ti4O7 with excellent conductivity and corrosion resistance can be combined with flexible self-supporting carbon nanofibers to avoid the shortcomings of Ti4O7 powder electrode in the form of "dead volume" and to alleviate the corrosion of carbon electrode, in order to improve its electrochemical performance. In this project, Ti4O7/C composite nanofibers were prepared by combining electrospinning technique and heat treatment process with in-situ reduction of carbon or reducing atmosphere. By fine regulation of the content ratio of Ti4O7 to carbon, specific surface area, grain size and distribution position were used to control the preparation of the material. The Ti4O7/C composite nanofibers with Ti4O7 grain size and position distribution were controllable designed to improve their electrochemical performance and clarify the structure-activity relationship of the "structure-electrochemical properties". And then optimize the process parameters in order to develop a new method for the controllable preparation of high performance Ti4O7/C composite nanofiber materials, and provide experimental basis for the development and application of new electrochemical energy storage devices.

Magneli 相Ti4O7是一种极具应用前景的陶瓷电极材料，可望应用于储能器件领域以缓解能源危机问题。目前该材料存在颗粒大、形貌控制难、比表面积低等问题，使其实际应用受到一定限制。申请人提出将导电性和耐腐蚀性优异的Ti4O7与柔性自支撑的碳纳米纤维复合，可控制备Ti4O7/C复合纳米纤维，可避免Ti4O7粉末电极易形成“死体积”的缺点并缓解碳材料的腐蚀问题。本项目采用静电纺丝法和热处理技术相结合，利用聚合物热解碳和流动H2分别与钛源热解的TiO2发生原位还原制备Ti4O7，并探讨其反应机理；通过精细调控Ti4O7和C的含量比、比表面积、晶粒尺寸及位置分布等形貌结构特征，可控制备Ti4O7/C复合纳米纤维；阐明其“结构-电化学性能”的构效关系；继而优化工艺参数以期发展出高性能Ti4O7/C复合纳米纤维材料可控制备的新方法，为新型电化学储能器件的发展与应用提展与应用提供实验基础。

Magneli 相Ti4O7是一种极具应用前景的陶瓷电极材料，可望应用于储能器件领域以缓解能源危机问题。目前该材料存在颗粒大、形貌控制难、比表面积低等问题，使其实际应用受到一定限制。申请人将导电性和耐腐蚀性优异的Ti4O7与柔性自支撑的碳纳米纤维复合，可控制备Ti4O7/C复合纳米纤维，可避免Ti4O7粉末电极易形成“死体积”的缺点并缓解碳材料的腐蚀问题。首先研究了Ti4O7碳热还原反应的热力学和动力学，基于氧势递增原理，对未知的亚氧化钛的热力学数据进行计算，建立了反应温度与吉布斯自由能之间的关系，计算表明Ti4O7的生成温度位于Ti5O9和Ti3O5之间，但间隔温度区间较窄，仅为50 K。碳热还原反应包括界面反应和扩散反应两个阶段，其活化能分别为272.0 kJ•mol-1和325.4 kJ•mol-1。物相演变规律为：Anatase-TiO2→Rutile-TiO2→Ti9O17→Ti8O15→Ti7O13→Ti6O11 →Ti5O9→Ti4O7→Ti3O5。在此基础上，采用静电纺丝法和热处理技术相结合，利用聚合物热解C与钛盐热解TiO2原位还原制备Ti4O7，研究了前驱体复合纳米纤维热分解过程、钛盐含量、热处理问题、保温时间、热处理气氛、分段热处理等多个实验参数并进行优化，结合样品的形貌结构表征，开发Ti4O7/C复合纳米纤维的可控制备技术；在三电极体系下，通过循环伏安法和交流阻抗法对Ti4O7/C复合纳米纤维电极材料的电化学性能进行测试。结果表明， 将高容量的Ti4O7与C复合获得的Ti4O7/C复合纳米纤维电极材料其比电容约为纯碳纤维比电容的3倍，本项目可为新型电化学储能器件的发展与应用提展与应用提供实验基础。