Currently, redox flow batteries are the most promising candidates for renewable energy storage in the field of MW-scaled electrical energy storage technologies, among which vanadium redox flow batteries (VRFBs) have advantages of wide application range, low maintenance cost, strong load balancing capability, long cycle life, etc.
In VRFBs, electrolyte is one of the important components, which has a significant impact on device performance and cost.
During the continuous electrolyte preparation, the vanadyl sulfate (V(IV)) solution from the mixing reactor is continuously in contact with the cathode of several cascaded cells, and the V(IV) solution is partially reduced to the V(III) solution in the first cell, and then completely converted to V(III) in the final cell. During electrochemical reduction, a solution of V(IV)/V(III) ratio 1:1, i.e., a neutral solution and a solution V(III) from the final cell, is used for VRFBs. Therefore, the real-time analysis of each vanadium species in the electrolyte preparation process is essential and of great significance.
Potentiometric titration is commonly used to directly determine vanadium electrolyte concentration. This method is not suitable for online monitoring because it is time-consuming and requires experiments. Recently, digital image-based methods have been selected for quantitative analysis in analytical chemistry. Moreover, the use of digital image analysis has attracted considerable attention in studying electrochemical processes with color changes. Digital image acquisition is a non-contact, non-invasive, cost-effective technique and it can overcome certain problems in classical spectroscopic analysis such as reduced and scattered spectral signals. These analytical methods have advantages such as low cost, high analytical accuracy and short analysis time.
Jon Sang Mo, a researcher at the Faculty of Chemical Engineering, has proposed a digital image-based analytical method to determine the concentration of vanadium species (V(IV)/V(III)) in the process of vanadium electrolyte preparation. Since this method is simple in procedure and less time-consuming compared to other analytical methods, it could be applied to real-time analysis in the process of electrolyte preparation.
You can find the details in his paper “Analysis of vanadium species(V(IV)/V(III) in the electrolyte manufacturing process for vanadium redox flow battery using digital image” in “Journal of Electroanalytical Chemistry” (SCI).
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