Enhanced mass transfer in nanofluid electrolytes for aqueous flow batteries: The mechanism of nanoparticles as catalysts for redox reactions. (June 2021)

• Record Type: Journal Article
• Authors: Kim, Jungmyung; Park, Heesung
• Is Part Of: Journal of energy storage. Volume 38(2021)
• Publication Date: 2021-06
• Subjects: Carboxyl-functionalized multi-walled carbon nanotubes -- Multi-walled carbon nanotubes -- Mass transfer -- Nanofluid -- Vanadium redox flow battery; Energy storage -- Periodicals; Energy storage -- Research -- Periodicals; 621.3126
• DOI: 10.1016/j.est.2021.102529
• Languages: English
• ISSNs: 2352-152X

Abstract

Highlights: The nanofluids achieve up to 5.6 times better mass transfer in the active area. The MWCNT based nanofluid acts as a physical catalyst in the VRFB active region. The nanofluid follows the outer-sphere (+) and inner-sphere (-) mechanisms. The nanofluids improve concentration loss through high mass transfer properties. Abstract: Carbon-based nanoparticles are introduced into the electrolytes of vanadium redox flow batteries and their impact on the electrochemical performance of these batteries is experimentally investigated. Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy characterizations reveal defects in the nanoparticles that act as active sites for electrochemical reactions. Cyclic voltammetry analysis reveals that the nanofluidic electrolytes exhibits higher oxidation/reduction kinetics and mass transfers than those of pristine electrolytes. The mass transfers of the VO 2+ /VO2 + electrolyte ions during oxidation/reduction reactions are 17.2% and 59.8%, respectively, while those of the V 2+ /V 3+ electrolyte ions are 5.6 times and 1.2 times higher than those of the VO 2+ and VO2 + electrolytes, respectively. Overall, these nanofluidic electrolytes enhance electron and mass transfers at the active region interface. According to the redox mechanism, the VO 2+ /VO2 + electrolytes have an increased active area, while the V 2+ /V 3+ electrolytes demonstrate excellent performance by acting as a catalyst to reduce the redox reaction activation energy. Graphical abstract: Image, graphical abstract