The Role of Proton in High Power Density Vanadium Redox Flow Batteries

Abstract

To design high-performance vanadium redox flow batteries (VRFBs), the influence of proton on electrocatalysts cannot be neglected considering the abundance of proton in a highly acidic electrolyte. Herein, the impact of proton on metal oxide-based electrocatalysts in VRFBs is investigated, and a proton-incorporating strategy is introduced for high power density VRFBs, in addition to unraveling the catalytic mechanism. This study discloses that the metal oxide-based electrocatalyst (WO3) undergoes in situ surface reconstruction by forming H0.5WO3 after incorporating proton. Experimental and theoretical results precisely disclose the catalytic active sites. The battery with H0.5WO3 designed by a proton-incorporating strategy achieves an attractive power density of 1.12 W cm–2 and sustains more than 900 cycles without an obvious decay, verifying the outstanding electrochemical performance of H0.5WO3. This work not only sheds light on the influence of proton on electrocatalysts for rational design of advanced VRFBs catalysts but also provides guidelines for the fundamental understanding of the reaction mechanism, which is highly important for the application of VRFBs.

The design engineering of nanocatalysts for high power redox flow batteries

“…In addition to the incorporation of metal nanocatalysts into all-vanadium RFBs to enhance the electrode reaction kinetics, researchers have redirected their focus toward metal oxides such as Mn 3 O 4 , 62 CoO, 63 SnO 2 , 64 ZrO 2 , 65 WO 3 , 66 etc ., taking into consideration both catalytic activity and cost issues. As early as 2017, incorporation of polydopamine-Mn 3 O 4 , a polyhedron with a size of around 100 nm, onto carbon felt in all-vanadium RFBs resulted in a notable enhancement in the system's performance metrics.…”

Critical Roles of pH and Activated Carbon on the Speciation and Performance of an Archetypal Organometallic Complex for Aqueous Redox Flow Batteries

“…RFBs using so-called "near-neutral pH" electrolytes are increasingly reported; however, the critical role of pH in their performance remains unexplored. Given the integral role protons are known to play in vanadium RFBs, e.g., participating directly in the reversible catholyte half-reaction 16 and in anolyte electrocatalysis, 17 the field has much less understanding of the impact of pH on performance in near-neutral RFB electrolytes, i.e., pH ≈ 2−12. Such electrolytes employing earth-abundant organic/organometallic active species such as those based on the dipyridyl moiety and iron are particularly popular for their cost and safety.…”

Controlled Construction of a N-Doped Carbon Nanotube Network Endows Carbon Felt with Superior Performances for High-Rate Vanadium Flow Batteries

“…As a result, the carbon-based electrodes fail to offer sufficient mass transfer channels and highly active catalytic interfaces, especially under high current densities, thus becoming the primary bottleneck in the development of high-power VFBs. To solve the aforementioned limitations associated with the carbon-based electrodes in VFBs, a comprehensive exploration has been conducted on various metal compounds , and carbon-based nanomaterials. , These materials have been investigated for their potential to generate active sites and enhance electrocatalytic performance with the aim of modifying the electrode materials.…”