Influence of Si on the Electrolyte Properties of Vanadium Redox Flow Battery

The effects of Si on the electrochemical performance and battery performance of the positive electrolyte of vanadium redox flow battery（VRFB） were studied by cyclic voltammetry,electrochemical impedance spectrum and charge-discharge test.The results indicate that with the content of Si in the electrolyte at 0.03 g/L,the diffusion coefficients of V（IV） species are decreased from（1.43～2.32）×10^-6 cm²/s to（1.23～1.99）×10^-6 cm²/s,and the value of electron transfer resistance is increased from 1.188 Ω·cm² to 1.593 Ω·cm²,resulting in the decrease in both of the electrochemical activity and the reversibility of V（IV）/V（V） reaction of the electrolyte.Meanwhile,the decay rates of capacity and energy of the battery are increased significantly,with the average coulombic efficiency and the average energy efficiency decreased by 1.39% and 3.23%,respectively.