鋅、鋅鋁、鋅鐵、氧化鋅之電化學研究

Electrochemistry of Zn-M materials, M = Nil, Al, Fe and oxygen

藍啟瑞(Chi-Jui Lan)

指導教授 ： 金重勳

國立清華大學/工學院/材料科學工程學系/博士(2007年)

摘要

本博士論文探究一些鋅基材料(鋅、鋅鋁合金、鋅鐵合金以及氧化鋅)之製備、電化學行為以及其應用。於研究的第一部份中，我們提出了兩套新式鹼性鋅鐵合金鍍浴系統，分別為氧化鋅-硫酸亞鐵-三乙醇胺-氫氧化鉀；以及氧化鋅-葡萄糖酸亞鐵-氫氧化鉀。相較於習用鹼性鋅鐵合金鍍浴，所提出之配方具有較高離子電導度(510-560 mS cm-1 相對於傳統之200 mS cm-1) ，較高陰極電流效率(16-31% 對 10-17%)以及更簡化之鍍浴組成；除此之外，藉由調變電鍍條件我們可以得到不同含鐵量(因而具有不同性質)之鋅鐵合金鍍層。在第二部分中，我們藉由賈凡尼鍍膜法及/或電鍍法於摻錫氧化銦玻璃基板上鍍著氧化鋅以及摻鉍氧化鋅。於65度C浴溫下，我們成功以賈凡尼鍍膜法鍍出似非晶相的缺鋅氧化鋅鍍層。我們發現到電鍍出之摻鉍氧化鋅鍍層的表面形貌、含鉍量以及電性質與電鍍條件息息相關。此摻鉍氧化鋅鍍層具有氧化鋅纖鋅礦結構，顯示出p型載子行為(載子濃度1.18*1017 cm3, 遷移率32.7 cm2 V-1 s-1) ，且其相較於未摻雜氧化鋅(為本質n型半導體)具有較低的電阻值(一萬倍的改變)。在最後一部份，我們組裝了一些鋅基測試電池做測試(鋅空氣電池或鎳鋅電池的架構)。我們發現到在金屬空氣電池的測試架構中，相對於純鋅金屬，鋅鋁合金薄片陽極展示出了較高的陽極電容量(800 mAh g-1 對 520 mAh g-1，最高測試值相比)，較高的開路電位(1480-1560 mV 比1460 mV)以及較輕微的鈍化現象。為了做電池循環測試，我們準備了兩種二次氫氧化鎳/氫氧化亞鎳電極(自製以及商用)。鋅鐵合金鍍浴做為二次鎳鋅電池的電解液時，於第一次充電(類似電鍍)有明顯抑制樹枝狀針晶的效果；溶液中不含鐵時於電流密度≧50 mA cm-2時針晶產生，溶液中含鐵時當電流密度高達800 mA cm-2時尚無針晶產生。然而，由於充放電電流效率太低(放電電容量/充電電容量比值小於25%)，因此尚須進一步研究才能真正達到實用。另一方面，我們證明了四烷基氫氧化胺可做為習用之樹枝狀鋅針晶抑制劑(四烷基溴化胺)的替代品。其抑制的效果取決於烷基的分子大小以及/或添加劑的濃度。這些添加劑對於空白溶液(0.45 M 氧化鋅加6.6 M 氫氧化鉀)之離子電導度並無不良影響且其為無毒化合物。於充放電循環測試中，我們發現到藉由添加0.1 M 四乙基氫氧化胺或0.005 M 四丙基氫氧化胺到空白溶液中，可以有效改善電池的循環壽命。

關鍵字

鋅 ； 鋅鋁合金 ； 鋅鐵合金 ； 氧化鋅 ； 電化學 ； 電池 ； 防蝕 ； 鹼性鍍浴 ； 摻鉍氧化鋅 ； 樹枝狀針晶 ； 電鍍

並列摘要

The preparation, electrochemical behaviors and applications of some Zn-based materials (Zn, Zn-Al alloy, Zn-Fe alloy and ZnO) are elucidated in this dissertation. In the first part, two novel alkaline baths for electrodeposition of Zn-Fe anti-corrosion coatings were disclosed, namely ZnO-FeSO4-triethanolamine-KOH and ZnO-(ferrous gluconate)-KOH systems. The proposed formulae exhibit higher ionic conductivity (about 510-560 mS cm-1 vs. 200 mS cm-1), higher cathodic efficiency (about 16-31% vs. 10-17%) and simpler constituents than conventional alkaline baths. Besides the Fe content in the deposits can be adjusted by tuning the deposition conditions thus Zn-Fe coatings with varied properties can be obtained. In the second part, undoped and Bi-doped ZnO layers were prepared by galvanic deposition and/or electrodeposition on ITO substrates. Amorphous-like Zn-deficient ZnO layers were successfully galvanic-deposited at 65 0C. The surface morphology, Bi content and electrical property of the Bi-doped ZnO deposits were strongly dependent on the deposition conditions. The electrodeposited Bi-doped ZnO layer showed XRD-pure ZnO wurtzite structure and demonstrated p-type carrier property (carrier concentration and mobility equaled to 1.18*1017 cm3 and 32.7 cm2 V-1s-1, respectively) with much lower resistance (about 4-order of magnitude) compare to undoped ZnO layer which was n-type in nature. In the last part, some Zn-based testing cells (in the forms of Zn-air or Ni-Zn batteries) were assembled and testified. Zn-Al alloy sheet anodes were demonstrated to be better anode metals than pure Zn. They showed not only higher anode capacity (800 mAh g-1 vs. 520 mAh g-1, the highest tested values), higher OCP value (1480-1560 mV vs. 1460 mV) but also less passivation in the metal-air battery configuration. In order to make cycling tests, two kinds of rechargeable Ni(OH)2/NiOOH electrodes (homemade and commercial ones) were prepared. The use of Zn-Fe baths as the electrolytes in secondary Ni-Zn batteries exhibited significant inhibition of dendrite (no dendrite appeared at 800 mA cm-2 compared with 50 mA cm-2 as the bath without Fe) in the first charge (deposition). However, the ratio of discharge/charge capacity was too low (less than 25%) to render true application, further studies will be required. On the other hand, tetra-alkyl ammonium hydroxides (TAAH) have been proposed and proved feasible as the alternatives for conventional inhibitors of Zn dendrite (tetra-alkyl ammonium bromides). The inhibition effect of TAAH was found to strongly depend on the size of alkyl groups and/or added concentration. These additives are not detrimental to ionic conductivity of zincate solutions (0.45 M ZnO + 6.6 M KOH) and are non-toxic. Highly improved rechargeability was achieved during cycling tests of a Ni-Zn cell by the addition of 0.1 M TEAH or 0.005 M TPAH into the zincate solutions.

並列關鍵字

Zn ； Zn-Al ； Zn-Fe ； ZnO ； Electrochemistry ； battery ； anti-corrosion ； alkaline baths ； Bi-doped ZnO ； dendrite ； electrodeposition

參考文獻

3. C. L. Mantell, Batteries and Energy Systems 2nd ed., McGraw-Hill, New York (1983).

4. V. Narasimhamurthy and B. S. Sheshadri, J. Appl. Electrochem., 26, 90 (1996).

5. V. Narasimhamurthy and B. S. Sheshadri, Met. Finish, 95, 44 (1997).

7. Z. Zhang, W. H. Leng, J. F. Li, J. Q. Zhang, J. M. Wang and C. N. Cao, Mater. Chem. Phys., 77, 497 (2002).

13. Z. N. Yang, Z. Zhang and J. Q. Zhang, Surf. Coat. Technol., 200, 4810 (2006).