The Research Of All Vanadium Redox Flow Battery Key Materials

As a novel and efficient energy storage system,all-vanadium redox flow battery had significant advantages compared with the more traditional batteries.To Improve the electrochemical Performances of Positive electrolyte of vanadium flow batteries, preparation of high concentration electrolyte,select of ion-exchange membrane, processing and modification of graphite felt electrodes,detection of positive electrolyte with different content GO additives were studied in detail in this dissertation.The main Points can be summarized as follows:1.The V(IV) electrolyte are prepared in reduction method and the oxalic acid was used as a reducing agent and this method is simple, safe, and low cost.Through the results of Uv-vis spectrum wavelength scanning,cyclic voltammetry and thermal stability test,we found that the vanadium ion is4valence in the electrolyte and the electrolyte have excellent stability.2.Compared with the performance of the battery of three types of ion exchange membranes assembly,The results show that the battery use Dupont Nafion-117membrane have the lowest internal resistance while barrier property of the diaphragm is best at the same time.This all reduced the self-discharge, improved the charge and discharge efficiency of battery.3.The results showed that:the best pretreatment temperature of the graphite felt is600℃, the heating time is4h-5h,at this point the graphite felt electrode have best electrochemical activity.Graphite felt was modified with graphene to enhance its property for vanadium redox battery, and the effect of different content on the cyclic voltammetry,battery capacity and energy efficiency performance was investigated. Results show that the graphite felt with0.5%graphene has best electrochemical property.The10times average discharge capacity of the cell employing graphite felt with0.5%graphene is12.9%higher than the blank one, and the average energy efficiency is3.37%higher than the blank one4.Graphene oxide(GO) was employed as an additive of positive electrolyte to enhance its property for vanadium redox battery, and the effect of different content:0.5%、1%、2%、3%GO on the conductivity, cyclic voltammetry, battery capacity and energy efficiency performance of electrolyte was investigated. Results show that at a scan rate of5mV·s-1，from the results of the1st cycle compared with the30th, it is found that our electrolyte has a good stability.The30times average discharge capacity of the cell employing positive electrolyte with1%GO is9.8%higher than the blank one, and the capacity retention ratio (85.30%) and average energy efficiency (79.40%) are both superior to the blank one79.26%and75.35%.