Improvement of Electrode Performance on the Alkali Metal Thermal to Electric Converter

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Micron-scale current collection leads for the Alkali Metal Thermal to Electric Converter (AMTEC) have been proposed and discussed in this study. The current collection leads are directly deposited on cathode side surfaces of the solid beta"-alumina electrolyte to eliminate the necessity for the conventional tied-on metal meshes. The new current collection leads also reduce electrical and mass transfer resistance in the cathode side electrodes of the AMTEC devices.The mass transport characteristics of sodium through the porous electrode strongly influence the output performance of the AMTEC cycle. Electrode electrical resistance and contact resistance between the porous electrode and the current collector also cause significant lowered power output in the AMTEC cycle. In order to improve the overall performance, both mass transport and electrical resistance must be improved simultaneously. The micron-scale current leads have a possibility to lower the overall electrical resistance with … More small increase in the mass transport resistance.The sodium exposure test cell (SETC) was newly fabricated and used to measure the mass transfer characteristics in the porous molybdenum electrode. The measured performance was examined and a mass transport model on the electrodes was introduced. On the other hands, the electrical characteristics of the leads were experimentally examined. The current leads of molybdenum were linearly deposited by Ar laser-induced thermal CVD method. The influence of depositing conditions, such as pressure, laser power, and writing speed, on the formed width and thickness of the leads was examined. The electrical resistance was also measured and the measured volumetric resistance of the deposited leads was 4-6 times as high as that of the bulk molybdenum.The analysis based on the measured data was also conducted. Various configurations include optimum width, distance and thickness were calculated. Compared result of the electrode performance having direct deposited current leads with that of the conventional tied-on collector has shown that its power density is about 35% higher even with its low electrical volumetric resistance. The effective of the current lead structure proposed in this study was verified. If the volumetric resistance of the deposited leads can be improved, much higher performance is expected with this method. Less