Research And Application Of Titanium Based Anodic Electrolyte For Liquid Flow Battery

Electrochemical properties and application of Titanium based anodic electrolyte for RFB were studied in this paper. The electrochemical properties were studied by electrochemical test methods. Explore the electrochemical reversibility of the electrolyte and the effect of concentration and temperature change on the performance of the electrolyte and the reaction mechanism of the electrolyte on the electrode surface. Ti-V RFB was assembled by different types ion exchange membrane for RFB, and the battery performance was compared. One ion membrane which is suitable for RFB was selected, then several specific performance of the Ti-V single cell was studied. The main contents of this paper are as follows:Titration curves (E-V curves) are made by potentiometric titration, and did a differential treatment to get a differential curve, the accurate concentration of the TiCl3 electrolyte is 1.3 mol/L. Cyclic voltammetry tests showed that the temperature rise is favorable for the electrochemical reversibility of Ti (?)/Ti (?) in the HCl solution; In the range of 10?40?, the reversibility of the electrochemical reaction has a positive correlation with the increase of temperature. The dynamic potential polarization test showed that the increase of temperature was beneficial to increase the transfer rate of electric charge on the electrode surface.AC impedance test showed that with the increase of temperature, the solution resistance of the electrolyte decreases and the diffusion coefficient of Ti3+ increases; the electrochemical reaction resistance is decreased, and the reaction kinetics coefficient is increased with the rise of temperature. AC impedance fitting results showed that the the ohmic resistance and the charge transfer impedance of the solution increase with the rise of the concentration. With the decrease of concentration of TiCl3, the electrochemical reaction resistance of the side reaction was decreased; RDE test showed that the diffusion coefficient of Ti3+ decreased with the increase of the concentration of solution. The limit current iL increases with the test rotation speed. The potential value of the Ti (?)/Ti (?) reaction was controlled both by diffusion and electrochemical reaction before the potential value of the platform; after the potential of the platform, the reaction is controlled by the electrochemical reaction independently with the active substance in timely manner.Ti-V RFB was assembled by three kind of ion exchange membrane as the separator, namely commercial Nafion117 cation exchange membrane(CEM), commercial FAA anion exchange membrane(AEM) and laboratory developed Cardo-QPEK anion exchange membrane(AEM). And the operation performance of the batteries was compared. The study found that Nafion117 has good ionic conductivity and low resistance against metal cations in the battery test; the ion conductivity of FAA membrane is poor and Cardo-QPEK not only has good ion conductivity, but also has good ion selectivity. The charging platform of the Ti-V RFB assembled of Cardo-QPEK is 1.2V, the discharge platform is 0.95V, the coulombic efficiency is between 98%-99.9%, the energy efficiency is 75%-76%.