Abstract: UV-VIS spectrophotometer was employed to investigate the permeation behavior in transmembrane electrolyte ions for all-vanadium redox flow battery (VFB).Emphasis is placed on the impact on transmembrane osmosis of VO²⁺ ions with external factors such as concentration,temperature,state-of-charge (SOC),electric field and osmotic pressure.It was helpful to explore the effects of ion diffusion and side reactions on the capacity loss for VFB by correlating the osmotic coefficient of different vanadium ions.The results indicate that it could increase the energy efficiency and reduce the transfer rate of VO²⁺ ions by improving the electrolyte concentration.Lowering the system temperature helps inhibit the cross-contamination during long term use and eliminating the side reactions.The osmotic coefficient of VO²⁺ ions decreased when increasing the SOC.As positive electric field was employed in electrolyte solution,VO²⁺ ions transmembrane diffusion would be accelerated within the aggravation of self-discharge; The osmotic pressure between the anode and cathode acclerates the permeation of VO²⁺,leading to a capacity loss for VFB.

Key words: all-vanadium redox flow battery, electrolyte, membrane permeation, mass transfer, osmotic coefficient

摘要： 采用静止型全钒氧化还原液流电池,利用紫外分光光度法,研究电解液钒离子跨膜渗透行为,讨论浓度、温度、荷电状态(SOC)、电场以及渗透压等对VO²⁺离子跨膜传质的影响,关联相应的钒离子渗透系数。研究结果表明,提高钒电解液浓度可以有效减缓钒离子跨膜传递速率,提高能量效率;适当降低体系温度,可以抑制钒离子的跨膜渗透,减小电池化学短路的发生;VO²⁺离子渗透系数随SOC值增加而迅速减小;正向电场存在会促进VO²⁺离子透膜扩散,加剧电池自放电;隔膜两侧液面渗透压的作用会加速钒离子跨膜渗透,造成电池容量衰减。

关键词: 全钒液流电池, 电解液, 膜渗透, 传质, 渗透系数