Novel electrode design having gradually increasing porosity in a vanadium redox flow battery

• Published in: Fuel (Guildford) Vol. 333; p. 126198
• Main Authors: Alphonse, Phil-Jacques, Taş, Mert, Elden, Gülşah
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2023
• Subjects: Electrode porosity; Energy storage; Numerical modeling; Vanadium redox flow battery; Numerical modeling; Electrode porosity; Vanadium redox flow battery; Energy storage
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2022.126198

[Display omitted] •The effects of an electrode having gradually increasing porosity on performance, charge, and mass transports in a Vanadium Redox Flow Battery.•A two-dimensional and steady-state numerical models composed of four different cases are developed.•The considered electrode porosity is gradually increased from 64% to 94% along the electrode thickness toward the membrane.•Case 4 has a higher potential performance, lower overpotential, and more uniform current distributions than the other cases.•The pressure difference in between inlet and outlet at the region having 64% porosity is too much in cases applied gradually increasing porosity. Vanadium redox flow battery systems safely and efficiently store energy obtained from conventional energy sources (e.g. natural gas, petroleum and coal, and so on.) and renewable energy sources (e.g. solar, and, so on.). These battery systems need to be analyzed in depth since they are one of the most attractive energy storage technology. This study numerically investigates the effects of gradually increasing electrode porosity on potential performance, overpotentials, current densities, species concentrations, and pressure distributions in the VRFB during discharge process. In order to reveal these effects, two-dimensional and steady-state numerical models composed of four different cases are solved. Electrode porosity is constant at 94% for both electrodes in Case 1. While the negative electrode porosity is gradually increased from 64% to 94% (step by 10%) along the electrode thickness towards the membrane in Case 2, the positive electrode porosity is gradually changed from 64% to 94% along the same direction in Case 3. The other electrode porosity is kept constant at 94% in Case 2 and Case 3. Case 4 has electrodes having gradually increasing porosity in both half-cells. The numerical results show that Case 4 has higher potential performance, lower overpotential, and more uniform current distributions than the other cases. Furthermore, there are slight changes in the concentration distributions of consumed and produced species in all cases. Moreover, pressure drop in the region having 64% porosity is too much in cases applied gradually increasing porosity.