Application of electrospinning for the fabrication of proton-exchange membrane fuel cell electrodes

Waldrop, Krysta; Wycisk, Ryszard; Pintauro, Peter N.

doi:10.1016/j.coelec.2020.03.007

Cited by 40 publications

(25 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To improve fuel cell performance, several studies have explored various alternate catalyst layer morphologies − to the conventional catalyst-coating layers with random morphologies . Electrospun nanofiber catalyst layer morphologies have recently attracted interest due to improved performance and durability compared to the conventional morphology. ,− These enhancements have been attributed to better dispersion of catalyst and ionomer phases, which maximizes the three-phase interaction (carbon–ionomer–catalyst interface) and thus increases catalyst utilization, and increased porosity (due to interfiber void fraction) that enhances the mass transport properties of the catalyst layer. ,, …”

Section: Introductionmentioning

confidence: 99%

“…3,6−10 These enhancements have been attributed to better dispersion of catalyst and ionomer phases, which maximizes the threephase interaction (carbon−ionomer−catalyst interface) and thus increases catalyst utilization, and increased porosity (due to interfiber void fraction) that enhances the mass transport properties of the catalyst layer. 8,10,11 Electrospinning is one of the common techniques to fabricate nanofiber catalyst layers. It allows fiber fabrication from a diverse set of materials and can produce fibers with a wide range of diameters.…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Toward Optimizing Electrospun Nanofiber Fuel Cell Catalyst Layers: Polymer–Particle Interactions and Spinnability

Khandavalli

Sharma-Nene

Kabir

et al. 2021

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

We investigate the effect of the poly(acrylic acid) (PAA) carrier polymer concentration on the microstructure and rheological properties of catalyst inks for electrospun polymer−electrolyte membrane fuel-cell catalyst layers. Characterization of an ink microstructure using oscillatory shear rheology showed that the catalyst particles (platinum on carbon) are significantly agglomerated in the absence of PAA or an ionomer. Both the ionomer and PAA promoted the stability of the particles against agglomeration via electrosteric stabilization by adsorbing onto the particle surface. Increasing the PAA concentration increased the stability of the particles (or reduced the agglomerated structure) due to increasing PAA coverage onto the free surface area of the particles. However, beyond a certain increase in concentration, PAA was found to predominantly remain as an excess free polymer in the ink due to an insufficient free/available surface area on the particles for further PAA coverage. Extensional rheology measurements demonstrated that PAA enhances the extensional viscosities of the inks. Consequently, increasing the PAA concentration in the ink promoted the evolution of uniform nanofibers. However, beyond a certain concentration, a significant increase in the shear viscosities of the inks led to defective fiber morphologies because of the onset of flow instabilities. Electrochemical performance comparisons between catalyst layers with different PAA concentrations showed maximum performance at the PAA concentration that led to the least agglomerated structure of the catalyst, most uniform fiber morphologies, and low concentrations of free (nonadsorbing) PAA in the electrode. These results provide a rationale for optimization of electrospun catalyst nanofibers for both spinnability and electrochemical performance.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Toward Optimizing Electrospun Nanofiber Fuel Cell Catalyst Layers: Polymer–Particle Interactions and Spinnability

Khandavalli

Sharma-Nene

Kabir

et al. 2021

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

show abstract

“…22 Alternatively, electrospinning emerged as a versatile tool for the fabrication of a fiber-based catalyst layer, posing many advantages over the other conventional techniques. 24,25 Thus, higher Pt utilization caused by even distribution along with the fiber results in a high-performing low-Pt-loading PEM fuel cell electrode. Furthermore, electrospinning allows sculpturing electrodes with a tailored porous network, allowing better mass transfer into and out of the electrode.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Specifically, numerous studies focused on improving the cathode performance and durability, while simultaneously reducing Pt catalyst and Nafion ionomer contents. − In this sense, numerous fabrication techniques were developed in favor of enhancing Pt utilization within the electrode such as decal transfer, brushing, and spraying . However, the aforementioned methods present numerous drawbacks such as pore blockage and nonuniformity in particle distribution. , Alternatively, electrospinning emerged as a versatile tool for the fabrication of a fiber-based catalyst layer, posing many advantages over the other conventional techniques. , Thus, higher Pt utilization caused by even distribution along with the fiber results in a high-performing low-Pt-loading PEM fuel cell electrode. Furthermore, electrospinning allows sculpturing electrodes with a tailored porous network, allowing better mass transfer into and out of the electrode.…”

Section: Introductionmentioning

confidence: 99%

Electrospun Nanofiber Electrodes for Boosted Performance and Durability at Lower Humidity Operation of PEM Fuel Cells

et al. 2022

View full text Add to dashboard Cite

The need for the development of new materials and strategies to enhance the performance of the PEM fuel cell at low humidity and platinum (Pt) loadings is becoming increasingly crucial. Due to this fact, the current study presents the fabrication of electrospun sulfonated silica (S-SiO 2 ) as a poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE))-based, flexible, freestanding, and highly porous novel cathode structure for PEM fuel cells. The developed fiber-based P(VDF-TrFE)/Pt/C/S-SiO 2 cathodes are compared with electrospun PVDF/Pt/C/S-SiO 2 , PVDF/Pt/C/Nafion, and conventionally sprayed electrodes to evaluate the utility of a new (carrier) P(VDF-TrFE) polymer in electrode structure. Morphological analyses revealed that S-SiO 2 and Pt/C particles were homogeneously distributed along the fibers without any significant agglomerations. The MEAs prepared by fiber-based P(VDF-TrFE)-Pt/C/S-SiO 2 cathodes with low Pt loadings (0.1−0.15 mg cm Pt −2) demonstrated promising fuel cell performance recording up to 417.7 mW cm −2 . It also exhibited a remarkable power output retention (98.2%) under partially humidified conditions. In situ electrochemical measurements reveal that enhanced particle distribution and Pt/S-SiO 2 surface contact results in the cathode performance surpassing that of conventional sprayed and fiber-based PVDF/Pt/C/Nafion cathodes. The fiber-based P(VDF-TrFE)/Pt/C/S-SiO 2 cathodes exhibited a promising durability record retaining up to 86.5% of their maximum power output after 30 000 cycles of a Pt-dissolution accelerated stress test (AST). Furthermore, P(VDF-TrFE)-Pt/C/S-SiO 2 cathodes with high S-SiO 2 loadings exhibited a 2.7% gain in maximum power density after 1000 cycles of a carbon corrosion durability test.

show abstract

“…In recent years, many research groups have focused on developing high-performance cathodes using strategies that include the synthesis of novel materials, ink-processing methods, system-level conditioning protocols, and modified electrode fabrication methods. − Among the promising electrode fabrication strategies, electrospinning catalyst/ionomer/polymer blends into nanofiber mats has gained considerable traction. Due to the high surface area-to-volume ratio and increased porosity of the fiber mats, the performance of nanofiber electrodes was found to be significantly improved compared to the conventional catalyst layers with random morphology. − …”

Section: Introductionmentioning

confidence: 99%

Toward Optimizing Electrospun Nanofiber Fuel Cell Catalyst Layers: Microstructure and Pt Accessibility

Kabir

Cleve

Khandavalli

et al. 2021

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

This work investigates how local ionomer/platinum (Pt) interactions and ionomer distribution in electrospun Pt/Vulcan nanofiber electrodes impact ionomer coverage, proton accessibility, and oxygen reduction reaction (ORR) performance in proton-exchange membrane fuel cells. Insights from various in situ electrochemical diagnostics were utilized in conjunction with ex situ microscopic characterization to understand how the electrode microstructureboth at the aggregate level and near the ionomer/platinum interfaceis affected by electrospinning in comparison to ultrasonic spraying. The effect of the carrier polymer poly(acrylic acid) (PAA) concentration from 5–20 wt % (with respect to total ink solids) on the resulting nanofiber morphology is discussed. Electron microscopy observations and CO displacement measurements indicated that Pt/Vulcan nanofibers prepared with a higher PAA concentration (15 wt %) were conformally coated with a film of ionomer on the exterior of the fiber, which resulted in an overall lower ionomer coverage on both Pt and carbon throughout the fiber diameter. In contrast, 10 wt % PAA leads to a uniform intrafiber distribution of the ionomer within the fibers, increasing the overall ionomer coverage and proton accessibility under both wet and dry conditions. These differences in the local ionomer coverage on Pt between 10 and 15 wt % PAA were also attributed to differences in the adsorption/interaction affinities between PAA and the ionomer onto the catalyst surface in the ink using zeta potential measurements. Additional fuel cell electrochemical tests on the electrospun electrodes show improvements in ORR kinetics and high-current-density H2/air performance compared to the ultrasonically sprayed electrodes.

show abstract

Application of electrospinning for the fabrication of proton-exchange membrane fuel cell electrodes

Cited by 40 publications

References 36 publications

Toward Optimizing Electrospun Nanofiber Fuel Cell Catalyst Layers: Polymer–Particle Interactions and Spinnability

Toward Optimizing Electrospun Nanofiber Fuel Cell Catalyst Layers: Polymer–Particle Interactions and Spinnability

Electrospun Nanofiber Electrodes for Boosted Performance and Durability at Lower Humidity Operation of PEM Fuel Cells

Toward Optimizing Electrospun Nanofiber Fuel Cell Catalyst Layers: Microstructure and Pt Accessibility

Contact Info

Product

Resources

About