Study On Vanadium Redox Flow Battery

The vanadium redox flow battery developed in recent years is a kind of new rechargeable battery. It is with excellent advantages, such as low cost and pollution, electrodes not involving reaction, power rating and energy rating being independent. For these reasons, much research and development has been concentrated on it.Many factors influence performance of vanadium battery, in which properties of electrode materials, positive and negative reactions are important. The main research purposes are focused on the modification of composite electrode used in vanadium battery and the mechanism of anodic oxidation on graphite electrode for V(IV), further more, single cell and cell stack were assembled using modified electrode and their performances and charge-discharge process were studied.The composite electrode was modified by adding titanate coupling agent and french chalk. The results showed that the resistivity of composite electrode was reduced by adding titanate coupling agent dissolved in kerosene, but increased by adding french chalk. Also, another modify method 'blend' was used. LLDPE/HDPE/CB, HDPE/MG/CB, HDPE/EG/CB blend system were studied. The blend system exhibits that the resistivity is lower in all blend system than in HDPE/CB system and the operation process is simpler as well. It is promising electrode material.The mechanism of anodic oxidation on graphite electrode for V(IV) was investgated using Linear Sweep Voltammetry method. The polarization curves for V(IV) oxidation in sulfuric acid solution were measured at different conditions such as various V(IV) and H₂SO₄ concentrations, stir condition and temperatures. Also cyclic voltammetry curve were tested at various scan rates. Studying these curves show that: 1. V(IV) oxidation reaction is irreversible and only one electron transfer during reaction; 2. The reaction consist of three step: one electron transfer and two proton transfers; 3. The possible reaction model for V(IV) oxidation is electrochemical-chemical-chemical (ECC) mechanism. The curves also indicated...