Two-Membrane Acid-Base Flow Battery with Hydrogen Electrodes for Neutralization-to-Electrical Energy Conversion

Acid-base flow batteries (ABFB) are a promising and environmentally benign class of flow batteries that utilize neutralization energy. Among the other flow batteries, ABFBs stand out with low cost and high solubility of the electrolytes and the possibility to harvest neutralization energy of acidic and alkaline wastewaters. However, the main ABFB issues, such as low power caused by discharge current limitation and low energy density, are limiting the possibility of their implementation. In this work, a novel two-membrane ABFB with two hydrogen electrodes was developed to overcome main ABFB issues. The proposed concept demonstrated high power density up to 6.1 mW cm^-2 at 13 mA cm^-2 . It was shown that battery performance was greatly limited by negative electrode overvoltage. Analysis of the voltage losses allowed to estimate main power losses and highlight the possible ways to its minimization.