Preparation process of 3.5 valence vanadium electrolyte by membrane electrolysis reduction process

3.5 valence vanadium electrolyte is an important component of vanadium batteries. The efficient preparation of 3.5 valence vanadium electrolyte is of great significance for vanadium energy storage. This article investigated the production process of 3.5 valence vanadium electrolyte through electrochemical reduction using V（IV） solution as raw material. The influence of electrodes, membrane types, current density and electrolysis temperature on the electrolysis process was investigated, it was found that using Ta as the anode and Pt as the cathode obtained the lowest electrolysis energy consumption. It was found that increase the current density leads to a decreased current efficiency and increased electrolysis energy consumption. While raised the electrolysis temperature lead to a decreased electrolysis voltage and energy consumption. The optimal electrolysis reduction process conditions was obtained at current density of 5 mA/m², electrolysis temperature of 50 ℃, at which the electrolysis energy consumption was 63.59 kW·h/m³ for producing 3.5 valent vanadium electrolyte.