期刊
ACTA PHYSICO-CHIMICA SINICA
卷 22, 期 4, 页码 403-408出版社
PEKING UNIV PRESS
DOI: 10.1016/S1872-1508(06)60012-0
关键词
vanadium redox flow battery; V(IV)/V(V); high concentration; electrode process
The electrode process of concentrated V(IV)/V(V) species has been studied at a graphite electrode using cyclic voltammetry, linear polarization, and impedance techniques. The results have revealed that in H2SO4, solution below 2 mol . L-1 containing 2.0 mol . L-1 V(IV), the electrode process of V(IV)/V(V) is controlled by the electrochemical polarization and diffusion with poor reversibility. When the concentration of H2SO4 is above 2 mol . L-1, the electrode process of V(IV)/V(V) turns into the diffusion control with improvement of the reversibility. An increase in concentration of H2SO4 solution facilitates a decrease in impedance, whereas too high concentration of H2SO4 solution ( > 3 mol . L-1) results in a remarkable increase in the viscosity of solution leading to a large mass transportation polarization, and thus the impedance starts to increase a bit. In 3 mol . L-1 H2SO4 solution, the reversibility and kinetics of V(IV)/V(V) are improved gradually as well as the characteristics of impedance with increasing concentration of V(IV) solution. But, when the concentration of V(IV) solution exceeds 2.0 mol . L-1, the viscosity of the solution is so high that the mass transportation polarization increases considerably, resulting in the deterioration of electrochemical performance of V(IV)/V(V) species and an increase in impedance. Therefore, considering from standpoint of increasing the energy density and electrode kinetics comprehensively, the optimal concentration of H2SO4 is 3 mol . L-1 containing 1.5-2.0 mol . L-1 of V(IV).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据