运行参数对全钒液流电池离子跨膜迁移的影响

Effect of operating parameters on ion cross transfer in all-vanadium redox battery

全钒液流电池(all-vanadium redox flow battery,VRFB)是特别适用于大规模储能的二次电池,但在实际应用过程中存在着正负极间不同价态的钒离子、硫酸根离子、氢离子和水的迁移现象。这会引起电解液中各种离子摩尔数的变化、电池容量的衰减和正负极间电解液体积差值的变化。因此,运行一段时间就要打开正负极间设置的联通管阀门混合电解液。针对正负极间电解液中各种离子的摩尔数变化情况建立VRFB的动态模型,分析流量、电流和充电状态(state of charge,SOC)范围等运行参数对正极或负极钒离子总摩尔数、硫酸根离子和氢离子总摩尔数变化的影响。如果SOC的运行范围合适,正负极间钒离子总摩尔数差值就会较小。所建模型与仿真结果将为运行过程中VRFB电解液组分的预测和调节提供有效的依据。

All vanadium redox flow battery(VRFB)is especially suitable for large-scale energy storage.However,in the practical application of VRFB,there are different valence states of vanadium ions,sulfate ions,hydrogen ions and water between the positive and negative electrodes.This will lead to the change of moles of various ions in the electrolyte,the attenuation of battery capacity and the change of electrolyte volume difference between positive and negative electrodes.Therefore,it is necessary to open the connecting pipe valve set between the positive and negative electrodes to mix electrolyte after running for a period of time.A dynamic model of VRFB was established to analyze the effects of operating parameters such as flow rate,current and state of charge(SOC)range on the total moles of vanadium ion,sulfate ion and hydrogen ion.If the operating range of SOC is suitable,the total moles difference of vanadium ions between positive and negative electrodes will be smaller.The model and simulation results will provide an effective basis for the prediction and regulation of VRFB electrolyte components during operation.