Effect of the catalytic ink preparation method on the performance of polymer electrolyte membrane fuel cells

Shin, Soyeon; Lee, J.-K.; Ha, Heung Yong; Hong, Seong Ahn; Chun, Honggu; Oh, Ingyu

doi:10.1016/s0378-7753(01)01045-x

Cited by 179 publications

(97 citation statements)

References 8 publications

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“…Shin et al 11 concluded that the electrodes fabricated using a n-butyl * Electrochemical Society Member. c Present address: Water Planet Engineering, Inglewood, CA 90301, USA.…”

Section: 21-25mentioning

confidence: 99%

“…This, in turn, will dictate the viscosity and surface tension of the ink, and ultimately, performance of the electrode since it governs the CL microstructure. 1,11 Poor Pt utilization occurs due to transport losses taking place at the macro and micro-scale of the CL. 12,13 The micro-scale transport depends on the aggregate structure and ionomer distribution in the CL.…”

mentioning

confidence: 99%

“…[18][19][20][21] Ink properties are also affected by the DM as observed in a number of studies comparing the electrochemical performances of electrodes with the same ink components but different DM. 11,[21][22][23][24][25] Shin et al 11 concluded that the electrodes fabricated using a n-butyl * Electrochemical Society Member. c Present address: Water Planet Engineering, Inglewood, CA 90301, USA.…”

mentioning

confidence: 99%

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Experimental and Theoretical Analysis of Ink Dispersion Stability for Polymer Electrolyte Fuel Cell Applications

Shukla

Bhattacharjee

Weber

et al. 2017

J. Electrochem. Soc.

107

108

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The aggregate size in fuel cell catalyst inks depends on the type of dispersion medium, particle concentration, and addition of stabilizing agents. In this work, ink stability and particle size of carbon black and carbon black/Nafion dispersions in four nonaqueous media, viz., methanol, ethanol, isopropanol and ethyl acetate are studied. Based on visual inspection, isopropanol is found to be the best medium for dispersion of carbon black inks. To rationalize this observation, a semi-empirical model based on diffusionlimited aggregation was developed to evaluate the rate of particle aggregation and predict the ink stability time for each dispersion medium. The proposed model supports the experimental observation by qualitatively predicting the same relationship between carbon stability and the dispersion media. The model also showed that the dielectric constant of the dispersion medium and the particle zeta potential are primarily responsible for the ink stability. Particle size for the different inks was determined by dynamic light scattering with and without dilution. Experimental results show that Nafion is a strong stabilizing agent, increasing the ink stability and decreasing the particle size of carbon aggregates. The beneficial effects of Nafion are independent of its concentration and are observed even at Nafion volume fractions of 10 wt%. The interaction energy is found to be a strong function of the surface potential for the dispersion medium with a higher dielectric constant. Most catalyst layer (CL) fabrication methods for polymerelectrolyte fuel cells (PEFCs) to date are based on wet deposition of a colloidal dispersion, i.e., the catalyst ink, onto either a membrane or a diffusion medium.1,2 The CL ink is usually a mixture of carbonsupported platinum particles, ionomer and a dispersion medium (DM). Ink stability, defined as the ability of particles to remain dispersed in the DM, and a reduced aggregate size are critical to deposition methods such as inkjet printing 3-6 and spray coating. 1,7,8 Inkjet printing allows for controlled spacial resolution, 6 however in order to create appropriate droplet sizes, the ink has to be ejected from micrometer size nozzles, 5 easily resulting in nozzle clogging. Inkjet printing of microporous layers using carbon ink has also been found to be extremely difficult unless ionomer solution, acting as a stabilizing agent, is added to the ink. 9 Similarly, spray coating requires inks to go through a nozzle, therefore clogging issues are likely to be a challenge when small nozzle sizes are used. Control over the aggregate size and the right selection of a DM to achieve the desired viscosity and surface tension therefore becomes critical in these deposition techniques. Further, the ink stability may also be important to larger commercial fabrication processes to increase the ink storage time.Even though the importance of appropriate ink recipes has been recognized, 1,10 very few studies have aimed at understanding the impact of DM on the ink stability. The type of DM, par...

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“…Shin et al 11 concluded that the electrodes fabricated using a n-butyl * Electrochemical Society Member. c Present address: Water Planet Engineering, Inglewood, CA 90301, USA.…”

Section: 21-25mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Experimental and Theoretical Analysis of Ink Dispersion Stability for Polymer Electrolyte Fuel Cell Applications

Shukla

Bhattacharjee

Weber

et al. 2017

J. Electrochem. Soc.

107

108

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“…4 Shin et al demonstrated that this colloid structure could be exploited to control the porosity of a catalyst layer. 15 Specifically larger pores were achieved with inks composed of PFSA * Electrochemical Society Student Member.…”

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confidence: 99%

Catalyst Layer Ink Interactions That Affect Coatability

Dixit

Harkey

Shen

et al. 2018

J. Electrochem. Soc.

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Catalyst layer inks are examples of biphasic material systems composed of a solid material, a polymer, and a solvent. Nanoscale interactions between the individual constituents can alter macroscopic properties that are relevant for coating and manufacturing processes (i.e. viscosity, surface tension, aggregation, and rheology). Control over these macroscale properties are important for controlled electrode formation during scalable roll-to-roll manufacturing. The underlying interactions include polymer|particle, particle|solvent, and polymer|solvent interactions. In this work we systematically investigate polymer|particle interactions via studying a range of formulated inks composed of different solvents (methanol, isopropyl alcohol, octanol, and water), varying polymer loadings, and particles with different surface charges. Ink aging is also addressed and over short time periods (<1 hr shelf life) the addition of a perfluorosulfonic acid ionomer was shown to stabilize the ink and also decrease the aggregation size. However, over long time periods (168 hrs) the aggregation size is independent of polymer loading, and approaches a steady state aggregation size around 350 nm. This equilibrium point suggests that the polymer is free to diffuse, adsorb, and relax within the excluded volume region. Furthermore, these results suggest that primary aggregates can be broken up with the addition of very low polymer loadings (15% I:C). A semi-empirical model is used to describe polymer|particle interactions within the ink, and the polymer coverage at the surface of the carbon was found to be the most sensitive parameter dictating ink stability. Finally, coating and rheology experiments are completed on all inks.

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“…Nafion in solution form (solvent ε > 10) can penetrate some pores and block the catalyst particles in them from reactants [224]. Generally, it can be said that catalyst ink solvents with dielectric a constant 3 < ε < 10 results in the best performance and large electrochemically active area.…”

Section: Catalyst Ink Solventsmentioning

confidence: 99%

Silicon nanograss as micro fuel cell gas diffusion layer

et al. 2010

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Direct methanol fuel cells (DMFC) produce electrical energy directly from chemical energy. They are a promising candidate for power sources of portable devices due to the high energy density of methanol and the quick recharging procedure by fuel insertion. However, the problem areas of the DMFC are the slow electro-oxidation of methanol and the permeated methanol reacting at the cathode. New catalysts are constantly searched but they are often tested only for catalytic activity and the DMFC testing is omitted even though the catalyst layer (CL) structure has a large impact on the performance. Miniaturization of the system is also necessary for portable applications. Silicon etching can be used to fabricate small structures for fuel cells replacing or enhancing the functions of laboratory-scale components.In the first part of this thesis, new catalysts for the DMFC are studied with the emphasis on the CL structure. Different carbon supports for the anode were studied: standard carbon black and alternative few-walled carbon nanotubes (FWCNT) and graphitized carbon nanofiber (GNF). The alternative supports showed better DMFC performance but their stability was lower than with carbon black. However, the CL formed with GNF showed a very porous structure enhancing the mass transfer, so that higher binder content could be used improving the stability to the level of carbon black and the performance by 30%. The FWCNTs were also investigated as a platform for enzymatic methanol oxidation by studying the electrochemical properties of an immobilized cofactor pyrroloquinoline quinone (PQQ). A large amount of PQQ was adsorbed having a strong redox response and good stability in a wide pH window. For the cathode, a methanol-tolerant, Pt-free nitrogen-doped FWCNTs were tested in an alkaline DMFC as such testing is not often made. Its performance was remarkably 4 times better than with Pt when synthetic air was used as the oxidant.In the second part of thesis, an integrated gas diffusion layer (GDL) consisting of Si nanoneedles (nanograss) was tested in a micro fuel cell (MFC). The layer functioned properly at low current densities. For high power applications, a standard carbon cloth GDL was tested with the nanograss as a contact surface reducing the resistance between the GDL and the flow field. The use of the nanograss improved the MFC performance and stability. Finally, the MFCs were used as a catalyst testing platform and the results were compared with a similar test in a laboratory-scale DMFC. The results varied showing that the DMFC components also have a large impact on catalyst testing.Keywords direct methanol fuel cell, carbon nanomaterials, micro fuel cells, catalyst layer Tiivistelmä Suorametanolipolttokennot (SMPK) tuottavat sähköenergiaa suoraan kemiallisesta energiasta. Ne ovat lupaava vaihtoehto kannettavien laitteiden voimanlähteeksi, koska metanolilla on korkea energiatiheys ja lataaminen tapahtuu nopeasti polttoainelisäyksellä. SMPK:lla on kuitenkin rajoitteina metanolin hidas hapetusreaktio ja katodi...

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Effect of the catalytic ink preparation method on the performance of polymer electrolyte membrane fuel cells

Cited by 179 publications

References 8 publications

Experimental and Theoretical Analysis of Ink Dispersion Stability for Polymer Electrolyte Fuel Cell Applications

Experimental and Theoretical Analysis of Ink Dispersion Stability for Polymer Electrolyte Fuel Cell Applications

Catalyst Layer Ink Interactions That Affect Coatability

Silicon nanograss as micro fuel cell gas diffusion layer

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