This technology produces a 3.5-valent vanadium electrolyte by reacting vanadium pentoxide (V2O5), a low-cost precursor, with a formic acid reducing agent in a catalytic reactor. To compensate for hydrogen ions consumed during the reaction, an acidic solution is added according to the formula (3A < W < 8A) to suppress pH changes and prevent performance degradation caused by ion permeation.
When producing a 3.5-valent electrolyte using vanadium pentoxide, which is cheaper than VOSO4, a significant amount of hydrogen ions are consumed during the reduction process, leading to an increase in pH. This results in lower electrolyte viscosity and increased vanadium ion crossover through the ion-selective membrane, causing capacity imbalance and a sharp decline in energy density and current efficiency.
This technology maintains pH balance by adding a second acidic solution containing hydrogen ions (W mole) at a ratio of 3A < W < 8A, preferably 5A ≤ W ≤ 6A, either before or after the catalytic reaction of vanadium pentoxide (A mole) with the reducing agent. It can be applied to large-capacity vanadium redox flow battery ESS, renewable energy storage systems, and electrolyte rebalancing processes, enabling the use of low-cost raw materials while suppressing long-term capacity decay caused by crossover.
This invention was developed with support from the Supercritical Material Industry Technology Center of the Ministry of Trade, Industry and Energy.
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