钒流电池负极电解液改性研究

全钒离子氧化还原液流电池(VRB)作为二次储能电池,具有循环寿命长、容量大、自放电小、污染小以及结构简单等优点,受到国内外研究者的广泛关注。但是VRB电解液仍然存在钒离子浓度过低、稳定性较差以及电化学反应速率低等问题,使VRB的应用受到限制。通过循环伏安法考察了添加剂尿素、草酸和酒石酸对负极电解液电化学反应速率的影响,发现合适浓度的尿素、草酸和酒石酸都可以部分增大其反应速率,提高电解液的可逆性,尤其以w(草酸)=0.5%效果最佳。对添加w(草酸)=0.5%的负极液进行了交流阻抗分析,发现草酸主要是降低了电化学反应电阻。最后通过电位滴定法研究了添加剂对负极液稳定性的影响,得出草酸和酒石酸都可以提高电解液稳定性的结论。

Negative Electrolyte Modification in the All Vanadium Redox Flow Battery

As an excellent rechargeable energy storage battery, all vanadium redox flow battery(VRB)has the advantages of long cycle life, large capacity, small self-discharge, little pollution, and simple structure. Therefore, all vanadium redox flow battery has been widely researched at home and abroad. However, there are some problems restricting the application of all vanadium redox flow battery, for example, low vanadium ion concentration, poor stability and low electrochemical reaction rate in the electrolyte and so on. In this paper, the influence of additives on the electrochemical reaction rate of negative electrolyte for all vanadium redox flow battery has been researched by CV. It is found that the apposite concentration of urea, oxalic acid and tartaric acid can partly increase the reaction rate and electrolyte reversible, especially 0.5% oxalic. Then, the negative electrolyte adding 0.5% oxalic acid was analyzed by AC impedance and found that oxalic acid was mainly to reduce the electrochemical reaction resistance. Finally, the effect of the additives on the stability of negative electrolyte for all vanadium redox flow battery has been studied by potentiometric titration analysis. Both oxalic acid and tartaric acid can effectively improve the stability of electrolyte, and the electrolyte of 1.93 mol/L V(Ⅲ) can be stable in more than 40 days at room temperature.