Optimal Porous Electrode Structures in All-Vanadium Redox Flow Batteries

<div class="section abstract"><div class="htmlview paragraph">To address the pressing issue of electrical fluctuations from renewable energy technologies, an energy storage system (ESS) is proposed. The vanadium redox flow battery (VRFB) is gaining significant attention due to its extended lifespan, durability, thermal safety, and independent power capacity, despite its high cost. Key components of the VRFB include a membrane, carbon electrode, bipolar plate, gasket, current collector, electrolyte, and pump. Among these, the carbon electrode and bipolar plate are the most expensive. Reducing capital costs in VRFB systems is crucial for advancing clean energy solutions. Conventional flow field designs like interdigitated flow field (IFF), serpentine flow field (SFF), and parallel flow field (PFF) are used to feed the electrolyte into the VRFB cell, necessitating thicker bipolar plates to avoid cracking during the machining process. This study focuses on optimizing the flow-through (FT) design, which eliminates the need for machining on bipolar plates, thus allowing for thinner bipolar plates. By enhancing cell performance through the design of porous electrode structures when operating at 5% depth of discharge (DoD), this study utilizes topology optimization, rather than conventional trial-and-error methods, to search for optimal porous electrode structures. The results revealed that an interdigitated-type flow channel design are created within the porous electrodes with different structures on both the positive and negative sides to achieve higher overall cell performance. The limiting current was found to be approximately 0.08, 0.13, and 0.41 A/cm<sup>2</sup> for the cases of homogeneous electrodes in FT, IFF, and optimized flow-through (OFT), respectively. The peak power density significantly improved by 284% and 155% compared with homogeneous porous electrodes in FT and IFF, respectively.</div></div>