Al元素对钒电池电解液电化学及电池性能影响研究

Influence of Al on Electrochemical Performances of Electrolyte and Battery of Vanadium Redox Battery

电解液作为全钒液流电池能量储存和转换的核心材料,其杂质含量在很大程度上影响电解液的物理化学性质、电极反应可逆性和电池的充放电性能。针对常见的杂质元素Al,研究其对电解液物理化学性质的影响规律,并采用循环伏安法和充放电测试等方法研究了Al元素对电解液电化学行为以及电池性能的影响规律。结果表明,随Al/V摩尔比的升高,电解液的黏度和密度升高,电导率明显降低,当Al/V摩尔比为1∶3.0时,黏度和密度分别增加64%和2.8%,电导率降低34%;Al离子降低了正极和负极反应的可逆性;随着Al/V摩尔比的升高,电池库伦效率升高,电压效率降低,能量效率降低,同时,Al离子降低了负极的运行稳定性。

As the core material for energy storage and conversion of vanadium redox battery,the composition of electrolyte,especially the impurity content in the solution,greatly affects the physicochemical properties of electrolyte,reversibility of electrode reactions and the charge-discharge performance of battery.The influence of Al concentration on the physicochemical properties of electrolyte was studied,and the effect of Al on the electrochemical performances of electrolyte and battery was analyzed by cyclic voltammetry and charge-discharge test.The results indicate that with the increase of Al/V(molar ratio),both of the viscosity and density of the electrolyte increase,with the conductivity obviously decreased.At the molar ratio of Al to V of 1∶3.0,the viscosity and density of the electrolyte increase by 64%and 2.8%respectively,and the conductivity of the electrolyte decreases by 34%.Furthermore,Al reduces the reversibility of positive and negative electrode reactions.Meanwhile,with increase in the molar ratio of Al to V,coulombic efficiency of the battery increases,with its voltage efficiency and energy efficiency significantly decreased.In addition,the stability of negative electrolyte is decreased due to the existence of Al.