Study of fuel cells using storable rocket propellants Final report, 28 Jan. 1964 - 29 Jan. 1965

Fuel cells using storable rocket propellants for reactant

Catalysts for electrochemical generation of oxygen

Several aspects of the electrolytic evolution of oxygen for use in life support systems are analyzed including kinetic studies of various metal and nonmetal electrode materials, the formation of underpotential films on electrodes, and electrode surface morphology and the use of single crystal metals. In order to investigate the role of surface morphology to electrochemical reactions, a low energy electron diffraction and an Auger electron spectrometer are combined with an electrochemical thin-layer cell allowing initial characterization of the surface, reaction run, and then a comparative surface analysis

Dimensionally stable anodes and their possibilities in neutral electrolytic pickling

Abstract. Dimensionally stable anodes (DSAs) are a type of anode materials in which the degradation process during electrolysis is significantly slower when compared to other traditionally used anodes. DSAs consist of substrate material (such as titanium) and an electro-active top layer. The electro-active layer consists of one or multiple metal oxides of the noble- or platinum group metals: ruthenium dioxide (RuO2), rhodium dioxide (RhO2), palladium dioxide (PdO2), osmium dioxide (OsO2), iridium dioxide (IrO2), and platinum dioxide (PtO2). In neutral electrolytic pickling stainless steel strips are pickled from the scale that has formed during the manufacturing process. Lead is typically used in neutral electrolytic pickling, however, during pickling lead-based anodes suffer from high overpotential towards oxygen evolution reaction (OER), corrosion and formation of impurities. It has been estimated that only around 10 % of the applied current during pickling goes to the pickling of the scale, and the other 90 % to the OER. DSAs with electro-active metal oxide coatings RuO2 and IrO2 are measured to have significantly lower overpotentials towards OER, allowing higher current efficiencies during pickling. So, it is important to study the possibilities that DSAs could bring to the industry of neutral electrolytic pickling and whether they could increase the current efficiency of the pickling process and by then reduce the overall operation costs in this era of increasing energy prices

New Simple Modification of Dip, Spray and Cathodic Electrodeposition Coating Methods for Wire Coating (3D Coating)

In the current paper three most applied coating methods modified to suit wire coating (three dimensional coating). Capillary-gravitational coating (CGM) with natural motions considered to compensate the lifting of substrates, which normally occurs in the dip coating method. Besides a new economic-environmental friendly spray coating (EESM) assisted by the motor rotating to coat different wires, and branched cathodic electrodeposition (BCE) used also for the same mission. Thoroughly, several tests and evaluations carried out for those applied techniques. Remarkably, easy application detected for all modified methods. Unusually perfect morphology output and functional layers were synthesized. Comparison of all mentioned methods carried out considering loses and the number of coating time. Evaluation analysis has been comprehensively considered to find out capability of using these methods later on in the future

Atomic Layer Deposition of Ru and RuO2: New Process Development, Fabrication of Heterostructured Nanoelectrodes, and Applications in Energy Storage

The ability to fabricate heterostructured nanomaterials with each layer of the structure having some specific function, i.e. energy storage, charge collection, etc., has recently attracted great interest. Of the techniques capable of this type of process, atomic layer deposition (ALD) remains unique due to its monolayer thickness control, extreme conformality, and wide variety of available materials. This work aims at using ALD to fabricate fully integrated heterostructured nanomaterials. To that end, two ALD processes, using a new and novel precursor, bis(2,6,6-trimethyl-cyclohexadienyl)ruthenium, were developed for Ru and RuO2 showing stable growth rates of 0.5 Å/cycle and 0.4 Å/cycle respectively. Both process are discussed and compared to similar processes reported in the literature. The Ru process is shown to have significantly lower nucleation while the RuO2 is the first fully characterized ALD process known. Using the fully developed RuO2 ALD process, thin film batteries were fabricated and tested in standard coin cell configurations. These cells showed high first cycle gravimetric capacities of ~1400 mAh/g, which significantly degraded after ~40 cycles. Rate performance was also studied and showed a decrease in 1st cycle capacity as a function of increased rate. These results represent the first reports of any RuO2 battery studied beyond 3 cycles. To understand the degradation mechanisms witnessed in the thin film studies in-situ TEM experiments were conducted. Single crystal RuO2 nanowires were grown using a vapor transport method. These nanowires were cycled inside a TEM using Li2O as an electrolyte and showed a ~95% volume expansion after lithiation, ~26% of which was irreversible. Furthermore, a chemical irreversibility was also witnessed, where the reaction products Ru and Li2O remain even after full delithiation. With these mechanisms in mind heterostructured nanowires were fabricated in an attempt to improve the cycling performance. Core/shell TiN/RuO2 and MWCNT/RuO2 structures were fabricating using the ALD process developed in this work. While the TiN/RuO2 structures did not show improved cycling performance due to connection issues, the MWCNT/RuO2 structure showed a stable areal capacity of ~600 μAh/cm2 after ~20 cycles and were easily cycled 100 times