Experimental Analysis of Inkjet Printed Polymer Electrolyte Fuel Cell Electrodes

• Author / Creator

  Shukla, Shantanu T

• The success of commercial applicability of polymer electrolyte fuel cells (PEFCs) depends on the cost competitiveness with respect to current energy sources. A major fraction of the system cost can be mitigated by reducing the amount of platinum (Pt) catalyst in the electrodes and by improving the catalyst utilization. The electrode fabrication process governs the electrode microstructure and Pt loading. Application of inkjet printing (IJP) to PEFC electrode fabrication is a relatively recent introduction and has not been extensively studied. The drop-on-demand nature of this method allows for a precise control over the deposition process, thickness and Pt loading of the electrodes. A detailed analysis of this method is therefore essential to understand its feasibility as a fabrication tool. In this work, a comprehensive analysis of inkjet printed electrodes has been carried out. By studying the effect of Nafion (from 10 wt% to 50 wt%) in thin, low Pt loading IJP electrodes, the performance is not found to be affected by Nafion loading in the range of 20 - 40 wt%. The effect of Pt loading on active area, Tafel slope, reaction order and evaluation of oxygen transport resistance for IJP electrodes has been carried out to understand their lower performance compared to a conventional spray coated electrode. The reduced performance of IJP electrodes at higher Pt loadings is associated to a reduction in the active area and porosity. In an attempt to improve reactant transport, a novel electrode coated membrane (ECM) architecture is developed where the carbon micro-porous layer (MPL) is fabricated directly over the catalyst layer. Results indicated a lower transport resistance in ECMs as compared to using an MPL based diffusion media. Inkjet printing is also implemented to study patterned electrode structures. However, fine enough patterns to show the advantage of patterned structures could not be observed.Lastly, a study of particle interactions using colloidal science is carried out to understand the effect of dispersion solvents on ink stability. A semi-empirical model based on diffusion limited aggregation is developed to evaluate the rate of particle aggregation and predict the stability time. Experimental determination of stability was carried out for carbon based inks in non-aqueous dispersion media based on visual inspection and measurement of particle size by dynamic light scattering. A qualitative comparison of the stability time between the model and experimental observation could be made. Overall, this work presents an improved performance of IJP electrodes compared to previous literature, possible reasons for the reduced performance compared to conventional electrodes based on detailed analysis of electrode parameters, a novel electrode coated membrane architecture using IJP that improves the transport resistance and a simple semi-empirical model for determination of ink dispersion stability.

• Subjects / Keywords

  • Fuel cell testing
  • Electrode fabrication
  • Colloidal interactions
  • Inkjet printing
  • Catalyst ink dispersion

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3XK8516J

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.