鋅顆粒燃料電池之流動電解液研究

Study of Flowing Electrolyte of Zinc Particle Fuel Cell

鄭伍富(Wu-Fu Cheng)

指導教授 ： 黃國修

國立臺北科技大學/機電學院/車輛工程系所/碩士(2009年)

摘要

鋅金屬燃料電池使用多孔性鋅板作為陽極，液態氫氧化鉀為電解液，當電池進行放電反應時，鋅板會氧化成為氧化鋅並且附著於陽極表面，導致鋅陽極反應面積減少使性能下降最終停止放電，此時必須更換鋅板才能使電池繼續運作。本研究使用鋅顆粒取代鋅板，以加料方式添加至電池中進行反應，並利用陽極反應時會溶解於電解液之特性施以流動電解液將反應物帶離電池中，且連續添加鋅顆粒，以補充被溶解之陽極部份，使電池維持在最佳的反應狀態下運作。
本實驗結果電池最大功率到達12W，對應之電壓為0.8V，功率最高點之電流密度約為300 mA/cm2。實驗研究參數包含流動電解液之濃度、溫度及流速，結果顯示KOH電解液濃度在40wt%時能有最高的電流密度輸出，陰極與陽極對電解液濃度需求正好相反，因此濃度過高或過低都不利於電池運作。電解液溫度越高對電池性能也越好，但溫度高於45℃後電池性能提升有趨緩現象，當溫度高於65℃時需考慮水分蒸發問題。電解液流速主要作用在於溶解鋅顆粒之反應物，實驗結果顯示電解液流速過快，不利於電池反應。陽極因為使用顆粒狀鋅金屬，因此需要靠集電網收集鋅顆粒反應所釋放之電子，本研究使用不同集電網面積及形狀進行測試，結果由I-V曲線發現，增加集電網面積能增加電池整體效能但影響並不明顯。空氣陰極部分在增加導電片面積後能明顯提高電池電流密度，影響較顯著。

關鍵字

鋅 ； 顆粒 ； 流動電解液 ； 相較於氫燃料

並列摘要

The zinc-air cells use a porous zinc plate as the anode, and the liquid KOH as the electrolyte. When the fuel cell is in a discharge process, the zinc plate will be oxidized into zinc oxide, and then zinc oxide will attach to surface of the anode. This situation will cause a reduction in the anodic reaction area of zinc, and discharge functioning become slowly, eventually, it will stop discharging power. At this time, you would have to change the zinc plate in order to keep the fuel cell operating. This research used zinc granules in place of the zinc plate, and used the feed method by adding zinc granules into the fuel cell to conduct the reaction. We utilized the property of anodic reaction that would dissolve zinc granules in the electrolyte, the reactant would be brought out of the fuel cell by adding fluid electrolyte. When the zinc granules were continuously added in order to supplement the dissolved reactant at the anode, it would allow the fuel cell to maintain operating under the condition of best reaction.
This experiment used 3W discharge of constant power to maintain the voltage above 0.7V. This could last for 230 minutes, with energy density 456Wh/kg and maximum power approximately 12W. The parameters of this experiment including the concentration, temperature, and velocity of the liquid electrolyte, experiment results revealed that when KOH electrolyte concentration was at 40wt%, it could have the highest current density output. The need of the electrolyte concentration for the cathode side and the anode side were simply just the opposite. Therefore, if the electrolyte were too high or too low, it would be detrimental to the operation of the cell. When the temperature of the electrolyte was higher, the functioning was better. However, when the temperature was higher than 45℃, the advancement of the performance would have a phenomenon of slowing down. The main function of the electrolyte velocity was to dissolve zinc granules’ reactant. The experiment of result revealed that if the electrolyte velocity were too fast, it would be detrimental to the cell’s reaction. The anode side needed to rely on the metal grid to collect the electrons released by the reaction of the zinc granules, because it used granular zinc. This research used metal grids with different sizes and shapes to conduct tests. The results were discovered through the I-V curve. When the sizes of the metal grids were increased, the overall efficiency of cell could be increased, but the effect was not very obvious. After increasing the size of the air cathode’s current-conducting plate, the current density of the cell was significantly increased, and the effect was more obvious.

並列關鍵字

Zinc ； Particle ； Flowing Electrolyte ； Compares in hydrogen fuel

參考文獻

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