Research On The Electrolyte Membrane For All Vanadium Redox Flow Battery

With the development of science and technology, the crises of energy and environment is on the rise. The vanadium redox flow battery(VRB) is a new electrochemical rechargeable battery. Due to its excellent advantages, such as low cost, high reliability, rapid charging and discharging, high efficiency and separable power rating and energy rating. It has already showed the great developement prospect in renewable energy power generation and load shifting areas. It has attracted extensive attention worldwide.Electrolyte membrane is the one of the most important materials of vanadium battery. Its performance is affects the working performance of the vanadium redox flow battery directly. At present there is no dedicated electrolyte membrane to vanadium battery. Nafion proton exchange membranes have been widely used in vanadium battery, but the machining processes of the membrane is complicated, the price is expensive and the penetration rate of vanadium ion is serious. In this paper have investigated the probability and electrochemical properties of OPBI and Im-SPI two tapes of membrane applied in the vanadium battery. As the consequence of the test, the OPBI membrane which doped with 10mol/L sulfuric acid has low permeability of vanadium ion and the capacity loss is small, but the internal resistance of the membrane is a little higher. The voltage efficiency and coulombic efficiency of the battery with the membrane exceed 75% and 95%. However, the proton conductivity of Im-SPI is 0.10S/cm, much higher than that of Nafion117 membrane while the permeability of VO2+ is 3.43E-07cm2/s, a little higher than that of Nafion117 membrane. The single cell test showed that the coulombic efficiency and voltage efficiency of Im-SPI membrane reached 99.67% and 82.41%. And the power efficiency improved 1.65% than that of Nafion117 membrane.The electrolyte is the energy carrier and active substance in vanadium battery electrochemical reactions. This paper used vanadium pentoxide as the original electrolyte materials. Vanadium pentoxide was reverted to vanadium trioxide by hydrogen at high temperature. Then, the original electrolyte with trivalent and tetravalent vanadium ion which mole ratio is 1:1 was made by adding a certain amount of vanadium pentoxide and vanadium trioxide to sulfuric acid solution.