Iron/iron redox flow batteries (IRFBs) are emerging as a cost-effective alternative to traditional energy storage systems. This study investigates the impact of key operational characteristics, specifically examining how various parameters influence efficiency, stability, and capacity retention. IRFB systems with a volume of 60 mL per tank (20.25 Ah L−1) demonstrated superior capacity utilization, achieving a coulombic efficiency (CE) of up to 95% and an energy efficiency (EE) of 61% over 25 charge/discharge cycles.
Redox flow batteries (RFBs) offer promising solutions for safe and durable stationary energy storage; however, high capital expenditures (CAPEX) hinder their commercialization.
We developed a method for low-contact-resistance welding of carbon-polymer composite plates to graphite felt electrodes and copper current collectors. Using our own extruded carbon-polymer composite plate with low carbon filling, we optimized two manufacturing methods: traditional hot-press welding and novel microwave welding.
Commercial electrolyte for vanadium flow batteries is modified by dilution with sulfuric and phosphoric acid so that series of electrolytes with total vanadium, total sulfate, and phosphate concentrations in the range from 1.4 to 1.7 m, 3.8 to 4.7 m, and 0.05 to 0.1 m, respectively, are prepared. The electrolyte samples of the series for positive and negative half-cells at various state-of-charges are produced by electrolysis and are investigated for stability in the range of temperatures from −20 to +65 °C. It is attempted to reveal a correlation between initial electrolyte formulation in terms of total vanadium and total sulfate concentrations, which are measurable parameters in practice, and electrolyte thermal stability properties. The study of negative electrolyte samples by headspace online mass spectrometry enables to detect hydrogen gas, which evolves by chemical reaction of vanadium(II) species with protons during thermally induced aging. The battery with vanadium electrolyte at 1.4 m total vanadium, 4.7 m total sulfate, and 0.1 m phosphate concentrations displays more stable operation in terms of capacity decay during galvanostatic charge–discharge cycles than the battery with electrolyte at 1.7 m vanadium, 3.8 m sulfate, and 0.05 m phosphate concentrations under the same conditions.
