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  • 學位論文

具多孔性棒狀結構之不同金屬鈷氧化物應用於鋰空氣電池陰極觸媒

Porous Rods of Different Metal Cobalt Oxide for Lithium-Air Battery

指導教授 : 劉如熹
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摘要


隨石化燃料快速消耗,不僅造成能源危機,其燃燒後所釋放之氣體亦對地球環境造成破壞,故綠色能源逐漸被重視開發。近年來各國不斷推廣電動車,欲使用乾淨之儲能電池替代汽油,達環境保護之目的。其中鋰空氣電池具高能量密度,相較現今所使用之鋰電池可大於十倍,故可大幅提升電動車之行駛距離,有助於未來電動車之推廣。 本研究主要為配製多孔洞棒狀之不同金屬鈷氧化物,並應用於鋰空氣電池之陰極觸媒。利用水熱法技術得之有機物再於空氣中進行燒結,其釋放二氧化碳與水氣體後即可產生具中孔洞之結構。 本研究乃探討以不同金屬(錳、鐵、鎳與鋅)取代四氧化三鈷中之鈷金屬,其對電池催化有何影響與原因。利用粉末X光繞射儀(X-ray diffraction; XRD)鑑定樣品之晶相及其結晶度,以掃描式電子顯微鏡(scanning electron microscope; SEM)觀測樣品表面形貌,並以X光電子能譜(X-ray photoelectron spectroscopy; XPS)與同步輻射產生之X光吸收光譜(X-ray absorption; XAS)分別量測樣品表面與整體之配位環境與其金屬氧化價數。經上述鑑定發現FeCo2O4中作為活性位之三價鈷成分最多,而二價鐵可能易於提供電子使氧氣還原增加其催化活性,故可得最低之充放電過電位與2350.0 mAh gc-1之高電容量。而其孔洞性亦幫助氧氣與電解液流通,使其可穩定循環充放電40圈。

並列摘要


Because fossil fuels are consumed rapidly by human, it not only causes the energy crisis but also releases greenhouse gases which will damage to the global environment. Therefore, it is gradually being attention to develop green energy. In recent years, many countries continue to promote electric vehicles. Clean storage batteries have potential to replace gasoline to reach the goal of environmental protection in the future. Lithium-air battery has a high energy density that is higher than ten times compared with lithium-ion battery. It is possible to significantly enhance the traveling distance to help promote electric vehicles. The study synthesized porous rods of different cobalt oxide (MCo2O4) by simple hydrothermal method for cathode of lithium-air battery. The study explored what is the influence as catalytic process if Co is replaced by Mn, Fe, Ni and Zn. We identified the phase and crystallinity by XRD, observed the morphology by SEM and measured the valence of metals by XPS. We found the surface of FeCo2O4 existed highest ratio of Co3+. So, oxygen can be adsorbed onto active sites easier. In the other hand, Fe2+ maybe can release electron easily to reduced oxygen because d orbital of Fe3+ is half filled. So, it can get highest discharging plateau and lowest charging plateau from charge-discharge profile. The porous structure can also help to get high capacity (2350 mAh gc-1) and good cycling performance (40 cycles).

並列關鍵字

Li-O2 battery metal oxide

參考文獻


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