本文關(guān)鍵詞： 鎳氫電池 鎂-鈷基儲(chǔ)氫合金電極 機(jī)械合金化 體心立方結(jié)構(gòu) 電化學(xué)性能　出處：《東南大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：鎂基儲(chǔ)氫合金是一種高容量、低成本的儲(chǔ)氫材料。其中鎂鈷系儲(chǔ)氫合金因其具有低溫吸氫性能,成為近些年研究的熱點(diǎn)。先前報(bào)導(dǎo)的鎂-鈷體系儲(chǔ)氫合金具有體心立方結(jié)構(gòu),且晶粒在納米尺度時(shí)具備有良好的吸氫性能。但是鎂-鈷基合金即使是在真空條件下也難以放出儲(chǔ)存的氫氣。對(duì)此,本研究將探索電化學(xué)條件下鎂-鈷基合金的可逆儲(chǔ)氫(充放電)性能。本論文以機(jī)械合金化的方法,制備了 Mg-Co二元合金,添加5 at.%Pd的Mg-Co三元合金,Mg50Co50 替代不同元素的 Mg45M5Co50(M = Zr,Ti,Pd)、Mg50CO45Pd5三元合金,以及Mg側(cè)替代不同含量Pd元素的Mg67-xP(xCo33 =1,3,5,7)三元合金。通過(guò)X射線衍射及透射電鏡分析,證實(shí)除了 Mg67CO33和短時(shí)間球磨的Mg67Co33-5 at.%Pd以外的所有合金的主相結(jié)構(gòu)均為單一的體心立方結(jié)構(gòu),且晶粒已細(xì)化至納米尺度。合金電極的充電放電測(cè)試顯示,隨著Mg含量的增加,二元Mg-Co合金的首次放電容量先增加后減小,循環(huán)穩(wěn)定性逐漸降低;對(duì)于Mg-Co-5 at.%Pd三元合金,容量逐漸升高,循環(huán)穩(wěn)定性逐漸降低。對(duì)于部分合金化的Mg67Co33,其容量?jī)H有14.7mAhg-1;添加5at.%Pd后,隨著球磨時(shí)間增加,容量逐漸升高,循環(huán)穩(wěn)定性增強(qiáng);Mg側(cè)替代不同含量的Pd元素,其容量隨著Pd含量的增加先升高后降低,循環(huán)穩(wěn)定性逐漸增強(qiáng)。Mg64Pd3Co33的容量為所有合金中最高,達(dá)到624.3 mAh g-1。對(duì)合金電極進(jìn)行線性極化、恒電位階躍等電化學(xué)動(dòng)力學(xué)的測(cè)試,結(jié)果顯示合金的動(dòng)力學(xué)性能隨著Mg含量的增加而升高,添加Pd或者替代元素,均能提升合金的動(dòng)力學(xué)性能。對(duì)合金電極進(jìn)行塔菲爾極化的測(cè)試,得到腐蝕電流密度的結(jié)果,表明合金的耐腐蝕性能隨著Mg含量的增加而降低,添加Pd或者替代元素,能夠提高合金的耐腐蝕性能。對(duì)五次循環(huán)后的合金粉末進(jìn)行X射線衍射和X射線光電子能譜的測(cè)試,結(jié)果表明合金粉末表面有氫氧化物生成,Pd元素能有效抑制Mg的腐蝕。對(duì)五次循環(huán)后的電解液進(jìn)行電感耦合等離子體質(zhì)譜的測(cè)試結(jié)果表明,電解液中有Mg離子存在,且隨著Pd元素含量的增加而減少。因此可以認(rèn)為合金的容量損失來(lái)自表面氫氧化物的形成,表面活性降低,以及Mg的溶解。
[Abstract]:Magnesium based hydrogen storage alloy is a kind of high capacity hydrogen storage materials with low cost. The cobalt magnesium based hydrogen storage alloys because of its hydrogen absorption properties of low temperature, become the focus of research in recent years. Previously reported magnesium cobalt system hydrogen storage alloy has a body centered cubic structure, and the grain size in the nano scale with hydrogen good. But the absorption properties of magnesium - cobalt alloy even difficult to release hydrogen storage under vacuum conditions. In this regard, this study will explore the reversible hydrogen storage under the condition of electrochemical magnesium cobalt based alloy (discharge) performance. This method on mechanical alloying of Mg-Co alloy was prepared two yuan 5, add at.%Pd Mg-Co three alloys, Mg50Co50 substitution of different elements Mg45M5Co50 (M = Zr, Ti, Pd, Mg50CO45Pd5) three yuan alloy, and Mg substitution with different content of Pd element Mg67-xP (xCo33 =1,3,5,7) three alloy. By X ray diffraction and transmission electron microscopy analysis confirmed. In addition to all the alloys except Mg67CO33 and Mg67Co33-5 short milling time of at.%Pd main phase structure are single bcc structure, and the grain has been refined to nanometer scale. The charge and discharge test alloy electrode shows that with the increase of Mg content, two yuan for the first time the discharge capacity of Mg-Co alloy increased first and then decreased, the cycle stability decreased; at.%Pd three yuan for the Mg-Co-5 alloy, the capacity gradually increased, the cycle stability decreased gradually. For some alloying of Mg67Co33, its capacity is only 14.7mAhg-1; after the addition of 5at.%Pd, with the increase of milling time, capacity gradually increased, the cycle stability enhancement; Pd Mg side instead of different content of elements of its capacity, with the increase of Pd content increased first and then decreased, the cycle stability gradually increased the capacity of the.Mg64Pd3Co33 is the highest in all alloys, up to 624.3 mAh g-1. linear polarization on the alloy electrode, constant power One step electrochemical kinetics test results show that the dynamic performance of the alloy increases with the increase of Mg content, add or replace the Pd elements, can improve the dynamic performance of both alloys. The Tafel polarization on the alloy electrode test, obtained results show that the corrosion current density and corrosion resistance of the alloys decrease with the increase of Mg content the addition of Pd or substitution elements can improve the corrosion resistance of alloy. X ray diffraction and X ray photoelectron spectroscopy test on the alloy powder after five cycles. The results show that the surface of the alloy powder with hydroxide formation, corrosion of Pd elements can effectively inhibit the Mg. Test results of inductively coupled plasma mass spectrometry the electrolyte after five cycles showed that Mg ions in the electrolyte, and decreases with the increase of Pd content. It can be concluded that the capacity of the alloys. The loss comes from the formation of the surface hydroxides, the decrease of the surface activity and the dissolution of the Mg.

【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG139.7

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1 詹樂(lè)宇;Mg-Co基儲(chǔ)氫電極合金的制備、結(jié)構(gòu)與電化學(xué)性能[D];東南大學(xué);2017年

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本文編號(hào)：1453647