PDF Publication Title:
Text from PDF Page: 007
Membranes 2022, 12, 1228 7 of 16 The silver chloride electrode was of a conventional construction: small reservoir filled by saturated KCl solution, into which silver wire coated with a layer of silver chloride was immersed. The reservoir possessed a liquid contact (through a frit made of porous sintered glass) with sulfuric acid solution, into which the end of the Luggin membrane capillary was also immersed, according to the diagram in Figure 3. The Luggin thin-film capillary was a strip of the Nafion-211 proton-exchange mem- brane located between the membrane and one of the electrodes of the MEA (electrode one (5) in Figure 3 or electrode two (6) in Figure 3), and pressed to the membrane by a gasket-limiter of the flow fields for fixing the position of the capillary to the electrode. Thus, one end of the proton-exchange membrane strip is connected to the polarizable part of the electrode, and the other is placed in an additional electrolyte volume external to the MEA, in which there is an additional non-polarizable reversible electrode (reference electrode) with a constant and known value of electrode potential. 2.2.5. Square-Wave Voltammetry for Evaluating the Crossover of Br-Containing Compounds To evaluate the crossover of Br-containing compounds through the proton-exchange membrane, the square-wave voltammetry method was chosen due to its sensitivity for low concentrations of electroactive particles (instead of the standard cyclic voltammetry method, which is not sensitive enough for these estimates of bromide ion concentrations). The concentration of HBr in the working electrode compartment of the three-electrode electrochemical cell was monitored by the electrochemical oxidation of the Br− anion at the Pt working electrode. The electrode was a 1 mm stationary Pt disk, manufactured by soldering platinum wire into a glass tube. The end of this tube with a soldered Pt wire was flat polished. A Potentiostat Autolab 302N (“Metrohm”, Herisau, Switzerland) was used to control the three-electrode cell. Square potential pulses were applied of at height of 20 mV at 25 Hz frequency within a 0.5–1.3 V potential interval, with an average rate of potential change (equal to 5 mV/s) towards positive values of potential. Measurements were performed periodically. Prior to measurements, calibration was carried out by adding aliquots of HBr to the working electrode compartment of the cell. 3. Results and Discussion The bromide oxidation process can be described as [57,64]: 6Br− +3H2O→BrO3− +5Br− +6H+ +6e−,E0 =1.41Vvs.SHE, (3) This reaction was studied by carrying out a charging half-cycle by passing a current 75 mA/cm2 density through the MEA of the hydrogen-bromate flow battery for the initial electrolyte composition: 0.3 M HBr + 3 M H2SO4. When the cell voltage reached 1.9 V, the current direction was reversed, thereby switching to the discharge half-cycle. Figure 4a demonstrates the resulting plot for the cell voltage vs. the number of equivalent charges passed during the process described above, i.e., the passed charge divided by the charge equivalent, Q/Qequiv. The latter is defined as the amount of charge required to change the oxidation degree of all Br atoms in the electrolyte by one unit which is equal to the product: Qequiv = C × V × F where C and V are the initial concentration of bromide anions in the electrolyte and its volume, respectively, and F is the Faraday constant.PDF Image | Hydrogen-Bromate Flow Battery
PDF Search Title:
Hydrogen-Bromate Flow BatteryOriginal File Name Searched:
membranes-12-01228-v2.pdfDIY PDF Search: Google It | Yahoo | Bing
Salgenx Redox Flow Battery Technology: Power up your energy storage game with Salgenx Salt Water Battery. With its advanced technology, the flow battery provides reliable, scalable, and sustainable energy storage for utility-scale projects. Upgrade to a Salgenx flow battery today and take control of your energy future.
CONTACT TEL: 608-238-6001 Email: greg@salgenx.com (Standard Web Page)