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为了优化碳酸锂和二氧化钛合成尖晶石Li4Ti5O12的工艺,实验采用TG、XRD、SEM等手段研究了该工艺的等温动力学。测试结果表明,在400℃时碳酸锂和二氧化钛的反应过程由扩散控制,在450℃时的反应过程由界面化学反应控制,在500~600℃时属于随机成核和随后生长机理,积分动力学方程为G(α)=[-ln(1-α)]2,表观活化能为191.35 kJ/mol。在动力学研究基础上,优化了合成工艺,其中850℃下反应8 h的产物的放电比容量为167 mA·h/g,循环25次后容量基本不变,表现出良好的循环性能。
In order to optimize the process of synthesizing spinel Li4Ti5O12 from lithium carbonate and titanium dioxide, the isothermal kinetics of the process was studied by means of TG, XRD and SEM. The results show that the reaction process of lithium carbonate and titanium dioxide is controlled by diffusion at 400 ℃. The reaction process at 450 ℃ is controlled by interfacial chemical reaction. At 500 ~ 600 ℃, nucleation and subsequent growth mechanism are random nucleation and the kinetics of integral kinetics The equation is G (α) = [- ln (1-α)] 2, and the apparent activation energy is 191.35 kJ / mol. Based on the kinetic study, the synthesis process was optimized. The discharge capacity of the product reacted at 850 ℃ for 8 h was 167 mA · h / g. After 25 cycles, the capacity of the product was almost unchanged, showing good cycling performance.