Abstract: In this study, electrochemical performance of titanium-trichloride-hydrochloride acid aqueous solution was investiageted. Cyclic voltammetry(CV), electrochemical impedance Spectroscopy (EIS) and potentiodynamic polarization curve tests were applied to study the electrochemical dynamics of Ti³⁺/Ti²⁺ such as reversibility and intrinsic mechanism at various temperatures. The CV results show that the oxide and reduce peak currents of Ti³⁺/Ti²⁺ couples increase with increasing temperature and the electrochemical reversibility become better as well. The EIS measured data were simulated by the LR_s(Q(R_ctW)) equivalent circuit model, and the results indicate that reaction impedance reduced sharply from 4.192 W ·cm² to 0.5321 W·cm² with the temperature increasing from 10℃ to 40℃. The potentiodynamic polarization curve results show the equilibrium potential shifted towards positively promoting negative electrolyte alternative for titanium based redox flow battery.

Key words: flow battery, Ti based electrolyte, electrochemistry, reaction kinetics

摘要： 探究了钛基-盐酸水溶液体系电解液的电化学性能。分别采用循环伏安法、电化学交流阻抗法和动电位扫描法研究了不同温度下电解液电对的电化学反应的可逆性和反应的内部作用机理, 以及TiCl₃的盐酸水溶液体系在石墨电极上的反应平衡电位、交换电流、传递系数等电极反应的动力学参数。循环伏安结果表明温度上升有利于体系的电化学反应的可逆性, 40℃时反应的可逆性最好。交流阻抗实验结果采用LR_s(Q(R_ctW))等效电路模型进行了拟合, 结果显示随着温度由10℃上升至40℃, 电化学阻抗R_ct 值由4.192 W·cm²降低到0.5321 W·cm², 表明温度上升可以显著降低电对在石墨电极上的电化学反应阻抗。动电位测试结果发现Ti(Ⅲ)/Ti(Ⅳ)的平衡电位随温度上升发生正方向的偏移, 可能是由于温度上升使得Ti在HCl溶液中的形态发生变化;交换电流也随温度上升而增加是由于温度上升有促进电极表面电化学反应的电荷传递。各种电化学测试结果显示TiCl₃的HCl水溶液是一种有应用前景的液流电池负极电解液。

关键词: 液流电池, 钛基电解液, 电化学, 反应动力学