Ultralow platinum loading for redox-flow battery by electrospinning the electrocatalyst and the ionomer in core-shell fibers

Saadi, Kobby; Fan, Xiaozong; Hardisty, Samuel S.; Pintauro, Peter N.; Zitoun, David

doi:10.1016/j.est.2022.106430

Cited by 5 publications

(2 citation statements)

References 24 publications

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“…For instance, commercial vanadium RFBs display a high LCOS, partly due to the cost of the vanadium electrolyte. Among the alternatives, the high-power H 2 /Br 2 RFB has been extensively studied and has shown the crossover as the main Achilles heel of the technology [ 2 , 3 , 4 , 5 , 6 ]. Other chemistries, like Zn/Br 2 and polysulfide/bromine, also suffer from the crossover of bromide species [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Permselectivity and Ionic Conductivity Study of Na+ and Br− Ions in Graphene Oxide-Based Membranes for Redox Flow Batteries

Flack,

Aixalà-Perelló,

Pedico

et al. 2023

Membranes

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Permselectivity of a membrane is central for the development of electrochemical energy storage devices with two redox couples, such as redox flow batteries (RFBs). In RFBs, Br3−/Br− couple is often used as a catholyte which can cross over to the anolyte, limiting the battery’s lifetime. Naturally, the development of permselective membranes is essential to the success of RFBs since state-of-the-art perfluorosulfonic acid (PFSA) is too costly. This study investigates membranes of graphene oxide (GO), polyvinylpyrrolidone (PVP), and imidazole (Im) as binder and linker, respectively. The GO membranes are compared to a standard PFSA membrane in terms of ionic conductivity (Na+) and permselectivity (exclusion of Br−). The ionic conduction is evaluated from electrochemical impedance spectroscopy and the permselectivity from two-compartment diffusion cells in a four-electrode system. Our findings suggest that the GO membranes reach conductivity and permselectivity comparable with standard PFSA membranes.

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Section: Introductionmentioning

confidence: 99%

Permselectivity and Ionic Conductivity Study of Na+ and Br− Ions in Graphene Oxide-Based Membranes for Redox Flow Batteries

Flack,

Aixalà-Perelló,

Pedico

et al. 2023

Membranes

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“…Carbon fiber electrodes with a high degree of graphitization, a high electrical conductivity, and a high fiber/electrolyte interfacial area performed remarkably well in a vanadium redox flow battery, with high energy and coulombic efficiencies. 10 More recently, 11 a Pt/ C/Nafion fiber mat hydrogen electrode was used in a H 2 /Br 2 redox flow battery with high power output at a low Pt loading, excellent roundtrip efficiency, and constant performance for 140 charge/ discharge cycles. Two different types of electrospun nanofibers have been used successfully as high-performance fuel cell electrodes: (i) pyrolyzed carbon fiber mats with a precious metal catalyst that is deposited/impregnated post-pyrolysis 12,13 and (ii) particle/ polymer fibers that are used directly as the electrode material, where the polymer serves two purposes; it binds the catalyst particles together and it has ion conducting properties.…”

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confidence: 99%

Electrospun Nanofiber Electrodes for High and Low Humidity PEMFC Operation

Waldrop

Slack

Gümeci

et al. 2023

J. Electrochem. Soc.

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MEAs with nanofiber mat electrodes containing Pt/C catalyst and Nafion binder were fabricated and evaluated. The electrodes were prepared by electrospinning a solution of catalyst powder, salt-form Nafion (with Na+, Li+, or Cs+ as the sulfonic acid counterion), and a carrier polymer of either polyethylene oxide or poly(acrylic acid). The carrier polymer was extracted prior to MEA testing by a hot water soaking step. The resulting fibers were 15-17% porous, with a core-shell-like morphology (a coating of primarily Nafion on the fiber surface). MEAs with anode/cathode catalyst loadings of 0.1 mgPt/cm2 each and a Nafion 211 membrane produced high power at both high and low relative humidity (RH) conditions in H2/air fuel cell tests, e.g., a maximum power density of 919 mW/cm2 at 100% RH and 832 mW/cm2 at 40% RH for a test at 80 °C and 200 kPaabs. The presence of nm-size pores within the fibers trapped water via capillary condensation during low RH feed gas testing, thus maintaining a high proton conductivity of the Nafion binder in the anode and cathode while minimizing/eliminating ionic isolation of catalyst particles in low water content, poorly conductive binder.

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