Justin Roller

Low Platinum Electrodes for Proton Exchange Fuel Cells Manufactured by Reactive Spray Deposition Technology

Reactive spray deposition technology (RSDT) is a method of depositing films or producing nanopowders through combustion of metal-organic compounds dissolved in a solvent. This technology produces powders of controllable size and quality by changing process parameters to control the stoichiometry of the final product. This results in a low-cost, continuous production method suitable for producing a wide range of fuel cell related catalyst films or powders. In this work, the system is modified for direct deposition of both unsupported and carbon supported layers on proton exchange membrane (PEM) fuel cells. The cell performance is investigated for platinum loadings of less than 0.15 mg/cm using a heterogeneous bi-layer consisting of a layer of unsupported platinum followed by a composite layer of Nafion®, carbon and platinum. Comparison to more traditional composite cathode architectures is made at loadings of 0.12 and 0.05 mgplatinum/cm. The composition and phase of the platinum catalyst is confirmed by XPS and XRD analysis while the particle size is analyzed by TEM microscopy. Cell voltages of 0.60 V at 1 A/cm using H2/O2 at a loading of 0.053 mgplatinum/cm have been achieved.

A Study on Reactive Spray Deposition Technology Processing Parameters in the Context of Pt Nanoparticle Formation

Abstract Catalytic materials are complex systems in which achieving the desired properties (i.e., activity, selectivity and stability) depends on exploiting the many degrees of freedom in surface and bulk composition, geometry, and defects. Flame aerosol synthesis is a process for producing nanoparticles with ample processing parameter space to tune the desired properties. Flame dynamics inside the reactor are determined by the input process variables such as solubility of precursor in the fuel; solvent boiling point; reactant flow rate and concentration; flow rates of air, fuel and the carrier gas; and the burner geometry. In this study, the processing parameters for reactive spray deposition technology, a flame-based synthesis method, are systematically evaluated to understand the residence times, reactant mixing, and temperature profiles of flames used in the synthesis of Pt nanoparticles. This provides a framework for further study and modeling. The flame temperature and length are also studied as a function of O2 and fuel flow rates.

Toward reliable and repeatable automated STEM-EDS metrology with high throughput

New materials and designs in complex 3D architectures in logic and memory devices have raised complexity in S/TEM metrology. In this paper, we report about a newly developed, automated, scanning transmission electron microscopy (STEM) based, energy dispersive X-ray spectroscopy (STEM-EDS) metrology method that addresses these challenges. Different methodologies toward repeatable and efficient, automated STEM-EDS metrology with high throughput are presented: we introduce the best known auto-EDS acquisition and quantification methods for robust and reliable metrology and present how electron exposure dose impacts the EDS metrology reproducibility, either due to poor signalto-noise ratio (SNR) at low dose or due to sample modifications at high dose conditions. Finally, we discuss the limitations of the STEM-EDS metrology technique and propose strategies to optimize the process both in terms of throughput and metrology reliability.

Automated STEM/EDS Metrology Characterization of 3D NAND Devices

The semiconductor and memory industries have experienced a major transition from conventional planar devices to complex 3D architectures, such as 3D NAND and FinFETs. New materials and designs have raised metrology complexity and greatly increased the number of critical dimension measurements required for process control. 3D NAND presents many metrology challenges including low contrast features, high aspect ratio trenches, and holes in multiple stacks. Many technologies, such as STEM/TEM imaging, critical dimension small angle X-ray spectroscopy (CD-SAXS) and through focus scanning optical microscopy, have been explored to address these metrology challenges. The techniques in their present forms haven’t adequately achieved the sensitivity and resolution to measure the required critical dimensions of these 3D NAND structures.

A Study on Co and Cu Oxides as Sintering Aids for Sm0.2Ce0.8O1.9 Electrolyte

In this study, an addition of Co and Cu oxides to Sm0.2Ce0.8O1.9 (SDC) was studied to improve the SDC sinterability. It has been found that both Co and Cu oxide are very effective as sintering aids, and the SDC sintering temperature can be reduced from 1400°C without aids to below 1000°C with only 1at.% of either Cu or Co. As compared to the pure SDC, a slight decrease of ionic conductivity was observed in SDC with Cu sintering aid. There is no obvious effect on electrochemical property of SDC with Co sintering aid under 2.5at.%.

A study in the formation of Li7La3Zr2Oi2 as a Garnet-Type Ionic Conductor Synthesized by Flame Combustion

Solid-state lithium batteries capable of stability against chemical reaction with Li up to voltages higher than 5.5 V are considered a promising alternative to liquid or gel electrolytes that dominate the Libattery market [1]. In addition, they can be deposited as thin film batteries (TFBs) and integrated directly onto microprocessor chips [2]. The transition to solid-state dry batteries will allow for miniaturization due to a decreased electrolyte thickness, easier handling during manufacture, increased safety due to the lack of a flammable electrolyte coupled with a wide electrochemical potential window, and by the reduced environmental impact of oxide based electrolytes.

Ultramicrotoming Pt Catalyzed Substrates and Dispersion Supports

In this present work, the implementation of microtomy for the preparation of samples of Pt deposited on polypropylene substrates, with and without other catalyst-supporting materials, has been studied. Microtomy is a widely used method to prepare polymers or composite materials, and is a particularly valuable tool when conventional techniques for ceramic or hard materials are not applicable. The use of microtomy for sample preparation has been extensively applied to the study of soft tissue in the biological area, but has been also successfully applied in materials science. Several techniques detailing the use of resins, embedding materials, stains and special procedures are well established for most organic tissues. Procedures for sectioning, including sectioning speed and angle of incidence, are also identified and developed with high precision. In the case of materials science, the use of microtomy for hard materials has not been extensive due to inherent problems related to the hardness of the material and subsequent mechanical damage. However, as illustrated here, it is a valuable tool for the study of polymers and polymer-based composites with thin inorganic catalyzed layers. Moreover, the use of microtome sections allows the analysis of the bulk structure in large samples. In addition to its use in producing TEM samples, it is also ideal for the observation of bulk morphologies by other techniques like VLM, SEM, and AFM. In this context, it is important to recognize that not all those techniques required the same conditions; e.g., it is not necessary to produce ultra-thin samples (~60nm) for VLM examination. In other cases, many problems related to thin sections can be avoided when analysis are performed on the surface of a microtomed bulk sample [1]. For example, the use of microtome sections of entire PEM membrane electrode assemblies has been used to study the structure of fuel cells, the changes in their structure after use, and the effects on the fuel cell performance [2].

Development Status of SOFC Cell and Stack Technology at NRC-IFCI

Solid Oxide Fuel Cell (SOFC) development was started at the National Research Council of Canada’s Institute for Fuel Cell Innovation (NRCIFCI) in 2003 with the goal to develop the next generation of SOFC’s for Canadian Industry. To accomplish this task, work focused on the development of low temperature cermet and metal supported cells, direct deposition methods, low temperature sintering, seal and stack technology. As of November 2006, 5 cm x 5 cm cermet supported cell performance has been improved to 900 mW/cm at 600°C. These components have been incorporated into short stacks developed at IFCI to continue the push to commercialize this technology. At the same time, direct deposition technology has progressed rapidly to the point where metal supported 5 x 5 cells can be fabricated using sintering temperatures below 850°C. Results of this work will be presented, along with the development path at IFCI.