298.15K下Li-Ti-H_2O系φ—pH图及Li_4Ti_5O_(12)的合成

φ—pH diagram of Li-Ti-H_2O system at 298.15 K and synthesis of Li_4Ti_5O_(12)

运用双参数模型和同系线性规律对Li2Ti3O7、Li4Ti5O12和Li4TiO4的标准生成吉布斯自由能进行估算,并绘制在298.15 K时,不同离子浓度下Ti-H2O系和Li-Ti-H2O系的φ—pH图。结果表明:在水溶液中,Li4Ti5O12在pH为4.1～13.7之间具有较大的热力学稳定区域,从热力学角度预测了从水溶液合成Li4Ti5O12的可能性,并通过实验在pH为9～10之间,采用TiCl4水溶液强制水解法制备出纯相尖晶石Li4Ti5O12,验证水溶液中合成Li4Ti5O12的可行性。

The standard Gibbs free energies of the formation of Li2Ti3O7,Li4Ti5O12 and Li4TiO4 were estimated using two-parameter model and congeneric linear rule.The φ-pH diagrams of Ti-H2O and Li-Ti-H2O systems at different concentrations were drawn at 298.15 K.The results show that Li4Ti5O12 has a thermodynamically stable area in a wide pH range between 4.1 and 13.7 in aqueous solution.This indicates a great possibility for the synthesis of Li4Ti5O12.The pure spinel Li4Ti5O12 is successfully obtained from an aqueous TiCl4 solution by forced hydrolysis at pH between 9 and 10.This indicates that the synthesis of Li4Ti5O12 in an aqueous solution is feasible.