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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71636

    Title: 電解質添加劑及其濃度於水系KOH電解質中對鋅二次電池陽極電化學性質的影響;Effects of various additives and their concentrations in aqueous KOH electrolyte on electrochemical performance of Zn electrodes for rechargeable batteries
    Authors: 郭秉軒;Kuo,Ping-Hsuan
    Contributors: 材料科學與工程研究所
    Keywords: 枝晶狀結構;循環效率;添加劑;鋅腐蝕;鹼性溶液;Dendrite formation;Current efficiency;additives;Zn corrosion;Alkaline solution
    Date: 2016-08-29
    Issue Date: 2016-10-13 13:23:52 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本研究從鋅空氣電池電解質的觀點切入,目的為解決鋅陽極在充放電過程中形成枝晶狀結構、在鹼性水溶液中易腐蝕等問題並提高循環效率。尋找合適的鋅來源及濃度,在含有0.3 M氧化鋅之6 M氫氧化鉀溶液中,加入不同種類添加劑並改變濃度,針對最佳參數條件做複合的動作。
    有機酸類添加劑中檸檬酸提高庫倫效率5.7 %,經過循環充放電後,表面型態方面鋅晶粒無明顯枝晶狀結構出現,添加較有助於細化電極表面生成的鋅晶粒,抑制形成枝晶狀結構。腐蝕測試方面,腐蝕電流下降157 μA/cm2 (約31.5 %) 相較無添加劑時,改變濃度參數後我們在750 ppm得到與3000 ppm近似庫倫效率值同時腐蝕電流值下降280 μA/cm2 (約56.2 %)為最適當濃度值。
    胺鹽類及其衍生物添加劑中,1-甲基哌嗪可使庫倫效率上升到80 %左右相較無添加劑時,腐蝕電流值下降102 μA/cm2 (約20.5 %),當降低濃度至750 ppm對腐蝕電流值降低230 μA/cm2 (約46.2%)為最多,效果最為顯著。聚乙烯亞胺在腐蝕抑制及修飾枝晶狀結構最為明顯,腐蝕電流值下降330 μA/cm2 (約66.4 %)最多,並隨著濃度的降低在50 ppm時我們能達到與無添加劑時相近庫倫效率值,並在腐蝕抑制及修飾枝晶狀結構依舊有良好的效果,腐蝕電流值下降380 μA/cm2 (約76.3 %)最多。最後依照不同類添加劑及濃度去做複合觀察是否有加乘效應。
    複合以上不同種類及濃度添加劑後,研究最佳組合為3000 ppm 1-甲基哌嗪與750 ppm檸檬酸,庫倫效率值能達到82 %同時氧化還原電荷量不損失,循環充放電後枝晶狀結構有效改善,腐蝕電流值下降46 %相較無添加劑時,複合後性質較個別單一添加劑好為最佳組合配方。
    ;From the viewpoint of electrolytes design, we aim at solving the zinc dendrites formation, facile corrosion and low coulombic efficiency during charge/discharge process in an alkaline aqueous solution. In 0.3 M ZnO/6 M KOH solution, the effects of electrolyte additives species and concentration on the aforementioned problems are investigated in this study.
    Our experimental results shows the addition of 3000 ppm citric acid helps promote the deposition/stripping coulombic efficiency by 5.7 %. After cyclic charge/discharge, the obtained dendrite-free morphology indicates that the additive inhibits the dendrites formation and refines zinc grains. Besides, the Tafel analyses shows a decrease of 157 μA/cm2 (~31.5 %) in corrosion current as compared to that without additive. By tuning the additive concentration to 750 ppm, a maximum decrease of 280 μA/cm2 (~56.2 %) is achieved without trading off against other properties.
    Among amine-based additives, the addition of 3000 ppm 1-methylpiperazine can promote coulombic efficiency to ~80% and decrease the corrosion current by 102 μA/cm2 (~20.5 %) as compared to that without additive. Reducing the concentration to 750 ppm also causes a more significant decrease by 230 μA/cm2 (~46.2 %). Polyethylenimine (PEI) additive demonstrates the best effect on inhibiting corrosion behavior and dendrite formation. While the concentration decreases from 3000 ppm to 50 ppm, the decrease amount of corrosion current is enhanced from 330 μA/cm2 (~66.4 %) to 380 μA/cm2 (~76.3 %).
    At last, the synergistic effects of the effective additives combination are discussed. After combing different additives and tuning their concentrations, we explore that the addition of 3000 ppm 1-methylpiperazine and 750 ppm citric acid can raise the coulombic efficiency to 82 % (without losing redox charge) and still retain the dendrite-free morphology. Moreover, the corrosion current decreases by 46 %, which shows a synergistic effect on suppressing zinc corrosion.
    Appears in Collections:[材料科學與工程研究所 ] 博碩士論文

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