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1	Thin layer sonoelectrochemistry Duda, Chester George 01 December 2012 (has links) This research exploits mild sonication in a thin layer electrochemical cell to enhance rates of reaction in systems under voltammetric perturbation. Sound waves propagate through a thin layer of condensed fluid to provide energy to the electrode solution interface in the form of pressure and temperature. The sonic energy provided in three dimensions can be exploited to enhance rates of heterogeneous electron transfer as the energy is harnessed at the two dimensional electrode interface. Enhanced rates of heterogeneous electron transfer are of interest both for fundamental reasons and for exploitation in electrochemical energy systems. The initial pilot studies were directed at demonstrating the impact of acoustic energy on heterogenous electron transfer. Redox couples with different electron transfer rates were evaluated. Whereas compounds with reversible electron transfer kinetics demonstrated little improvement, redox couples such as ferric ion (Fe3+) with slow electron transfer kinetics exhibited an increase in the standard heterogeneous electron transfer rate constant, k0 with an increase in acoustic energy. The reduction of oxygen is a complex four proton, four electron process that is of technological importance. Slow kinetics of the oxygen reduction is a primary loss of efficiency in electrochemical power sources. Much like the ferric ion, oxygen kinetic rats improve. Preliminary studies in the oxidation of methanol demonstrated a sonocatalyic effect in methanol electrolysis that is of particular interest for the development of liquid based fuel cells. Sonication can both clean and destroy surface materials. The cleaning power inherent in sonication improves electrocatalysis and removes deposits and oxides from the electrode surface. acoustocatalysis Electochemistry electrokinetics oxygen reduction reaction sonochemistry Chemistry
2	Characterization of the gas composition inside NiMH batteries during charge using GC-MS Niklasson, Lovisa January 2018 (has links) The aim of the project was to develop a method to measure and studythe degree of activation of the negative electrode (MH) in a NiMH battery.This was done by characterization of the gases produced during charge of a battery – O2 and H2 – using a Gas Chromatograph. The current applied in the very first charge of the battery was varied in order to examine how this affects the gas evolution. In the developed method, batteries were charged to 8Ah with 9A, after which a gas sample was taken and analyzed with Gas Chromatography. An additional goal was to use the method to examine the difference in activation between virgin and recycled negative electrode material. A module charged stepwise with 0.07C followed by 0.2C had the lowest share of H2 after two cycles, indicated best activation. However, a higher amount of H2 in the beginning of the activation process could possibly enhance the degree of activation during the following cycles. The method indicated that the module with recycled MH was better activated than the virgin MH. To improve the technique, repeated measurements to get better statistics should be done. Gas samples should be taken at dV/dt=0 in order to take samples at same SoC. The charge current should be adjusted so that the same C rate is always used. This would make the results easier to interpret. NiMH batteries Batteries Nickel-metal hydride Nickel hydroxide Metalhydride Gas evolution Oxygen Hydrogen Electochemistry Gas Chromatography NiMH-batterier Batterier Nickel-metalhydrid Nickelhydroxid Metalhydride Gasutveckling Syrgas Vätgas Elektrokemi Gaskromatografi Inorganic Chemistry Oorganisk kemi Chemical Engineering Kemiteknik Other Chemical Engineering Annan kemiteknik Materials Chemistry Materialkemi Analytical Chemistry Analytisk kemi Other Chemistry Topics Annan kemi Chemical Sciences Kemi Other Chemistry Topics Annan kemi

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Thin layer sonoelectrochemistry

Characterization of the gas composition inside NiMH batteries during charge using GC-MS