Development Of A Test System For Vanadium Redox Flow Battery And Experimental Study

With the rapidly expanding need for large electrical energy storage systems in connectionwith renewable energy sources,flow batteries,have attracted enormous attention from both academia and industry due to their high flexibility in upgrade and low cost associated with scale-up.A number of implementations ranging from kW/kWh to MW/MWh for both demonstration and commercial application have been realised for different purposes throughout the world.Of all the flow batteries,vanadium redox flow battery(VFB)pioneered by Skyllas-Kazacos and co-workers at the University of New South Wales back in 1980 s has been widely regarded as the most suited option for large energy storage by virtue of the use of same element in both half-cell solutions that overcomes the inherent issue of cross contamination by diffusion ofdifferent ions across the membrane.Together with the absence of any toxic emissions,the vanadium redox flow battery has demonstrated its uniqueness in terms of safety and long life cycle.Firstly,this paper introduce the characteristics,application and structure of all vanadium redox flow battery,and summarize the characteristics of all vanadium redox flow battery and the system.In order to establish a multi-functional battery testing system,the remote control of programmable DC power supply and DC electronic load using Labview was implemented.This charging/discharging device,constructed by independent power supply and electronic load,could be configured with computer for galvanostatic(CC)-potentiostatic(CV)discharge or pulse discharge.Real time data including voltage,current were acquired periodically for further studying the characteristics of flow battery.Under different conditions,test the output efficiency of the battery,including different liquid supply periods,different flow rates,etc.,and analyze the experimental results.The experimental results show that it has some reference value to improve the efficiency of all vanadium redox flow battery system by controlling the flow rate.Premature voltage cut-off in the operation of the vanadium redox flow battery is largely associated with the rise in concentration overpotential at high state-of-charge(SOC)or state-of-discharge(SOD).The use of high constant volumetric flow rate will reduce concentration overpotential,although potentially at the cost of consuming excessive pumping energy which in turn lowers system efficiency.On the other hand,any improper reduction in flow rate will also limit the operating SOC and lead to deterioration in battery efficiency.Pressure drop losses are further exacerbated by the need to reduce shunt currents in flow battery stacks that requires the use of long,narrow channels and manifolds.Simulation results under preset voltage cut-off limits haveshown that variable flow rates are superior to constant flow rates for the given system design...