Influence of Cr^(3+) concentration on the electrochemical behavior of the anolyte for vanadium redox flow batteries  

作　　者：HUANG Fei ZHAO Qiang LUO ChunHui WANG GuiXin YAN KangPing LUO DongMei 

机构地区：[1]College of Chemical Engineering,Sichuan University,Chengdu 610065,China [2]PanGang Group Panzhihua Iron&Steel Research Institute,Panzhihua 617000,China

出　　处：《Chinese Science Bulletin》2012年第32期4237-4243,共7页

基　　金：supported by Youth Foundation of Sichuan University (07046);PanGang Group Panzhihua Iron & Steel Research Institute (11H0762)

摘　　要：The composition of electrolyte affects to a great extent the electrochemical performance of vanadium redox flow batteries(VRB).The effects of Cr3+ concentration in the anolyte on the electrode process of V(V)/V(IV) couple have been investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).It was found that Cr3+ causes no side reactions,but affects the electrochemical performance of V(V)/V(IV) redox reaction,including the reaction activity,the reversibility of electrode reaction,the diffusivity of vanadium ions,the interface film impedance,and the electrode reaction impedance.The experimental results show that Cr3+ within a certain concentration range can improve the reversibility of electrode reaction and the diffusion of vanadium ions.With the Cr3+ concentration increasing from 0 to 0.30 g L-1,the reversibility of V(V)/V(IV) reaction increases,while the diffusion resistance decreases.Correspondingly,the diffusion coefficient of vanadium ions increases from(5.48-6.77) × 10-7 to(6.82-8.44) × 10-7 cm2 s-1,an increase of ～24%.However,the diffusion resistance increases and the diffusion coefficient decreases when Cr3+ concentration is over 0.30 g L-1,while the impedances of the interface,the film as well as the charge transfer increase continuously.As a result,Cr3+ with a certain concentration improves the diffusion and mass transfer process,but the resistances of the film,the interface,and the charge transfer rise.Furthermore,Cr3+ concentration of no more than 0.10 g L-1 has few effect on the electrode reaction process,and that of no more than 0.30 g L-1 is favorable to the diffusion of vanadium ions.The composition of electrolyte affects to a great extent the electrochemical performance of vanadium redox flow batteries （VRB）. The effects of Cr3＋ concentration in the anolyte on the electrode process of V（V）/V（IV） couple have been investigated by cyclic voltammetry （CV） and electrochemical impedance spectroscopy （EIS）. It was found that Cr3＋ causes no side reactions, but affects the electrochemical performance of V（V）/V（IV） redox reaction, including the reaction activity, the reversibility of electrode reaction, the diffusivity of vanadium ions, the interface film impedance, and the electrode reaction impedance. The experimental resuits show that Cr3＋ within a certain concentration range can improve the reversibility of electrode reaction and the diffusion of vanadium ions. With the Cr3＋concentration increasing from 0 to 0.30 g L-1, the reversibility of V（V）/V（IV） reaction increases, while the diffusion resistance decreases. Correspondingly, the diffusion coefficient of vanadium ions increases from （5.48-5.77） × 10-7 to （6.82-8.44） × 10-7 cm2 s 1, an increase of -24%. However, the diffusion resistance increases and the diffusion coefficient decreases when Cr3＋ concentration is over 0.30 g L-1, while the impedances of the interface, the film as well as the charge transfer increase continuously. As a result, Cr3＋ with a certain concentration improves the diffusion and mass transfer process, but the resistances of the film, the interface, and the charge transfer rise. Furthermore, Cr3＋ concentration of no more than 0.10 g L-1 has few effect on the electrode reaction process, and that of no more than 0.30 g L-1 is favorable to the diffusion of vanadium ions.

关 键 词：钒氧化还原液流电池 铬浓度 三价铬 阳极液 电化学行为 电化学阻抗谱 扩散系数 电化学性能 

分 类 号：TM912[电气工程—电力电子与电力传动]