Modeling the trade-off between performance and pressure drop of bimodal pore size electrodes in vanadium redox flow batteries: Parallel vs. Series arrangement Articles uri icon

authors

  • GARCIA SALABERRI, PABLO ANGEL

publication date

  • November 2024

start page

  • 1

end page

  • 26

volume

  • 232

International Standard Serial Number (ISSN)

  • 0017-9310

Electronic International Standard Serial Number (EISSN)

  • 1879-2189

abstract

  • Vanadium redox flow batteries (VRFB) are promising large-scale energy storage system to accommodate the
    intermittency of renewable energy sources. However, cost reduction is necessary to make the technology more
    affordable and extend their commercialization worldwide. This goal can be achieved through the design
    of porous electrodes with enhanced performance and reduced pressure drop. Recently, bimodal pore-size
    electrodes, featuring interconnected macro and microporous regions, have emerged as a tailored solution for
    the design of next-generation VRFBs. In this work, the trade-off between performance and pressure drop
    of bimodal electrodes is examined numerically for two structural configurations: (𝑖) parallel arrangement
    (cylindrical macroporous regions aligned in the flow direction), and (𝑖𝑖) series arrangement (cylindrical
    macroporous regions perpendicular to the flow direction). The model predictions for a flow-through flow
    field are validated in terms of discharge polarization curves as a function of the feed flow rate and state of
    charge. Then, a parametric analysis is presented for the two porous structures as a function of the feed velocity,
    macroporous volume fraction, and microporous pore radius. The results show that microporous regions (∼ 2 μm
    in radius) provide high performance thanks to their large specific surface area, while macroporous regions
    (25 μm in radius) with a volume fraction around 0.5-0.6 decrease pressure drop. High performance with
    reduced pressure drop can be achieved with bimodal electrodes arranged in parallel at high stoichiometries
    and in series at stoichiometries close to one. The latter option is preferred to maximize the energy efficiency
    at low electrolyte velocity, significantly reducing pumping power requirements.

subjects

  • Renewable Energies

keywords

  • performance; pressure drop; bimodal electrode; modeling; vanadium redox flow battery