本文選題：鋰空氣電池 + KB　； 參考：《深圳大學》2015年碩士論文

【摘要】：鋰空氣電池理論能量密度高達11425 Wh/kg(不包括氧氣),與鋰離子電池、燃料電池、空氣電池相比,是迄今為止能量密度最大的儲能體系,吸引了全世界研究人員的關(guān)注。研究開發(fā)高能鋰空氣電池,有望解決全球所面臨的能源短缺、環(huán)境污染、油價飆升及能源爭奪戰(zhàn)爭等問題,特別是為電動汽車的長距離行駛,提供了新的實現(xiàn)途徑。在鋰空氣電池中,空氣正極作為發(fā)生氧化還原反應(yīng)和容納放電產(chǎn)物的主要場所,不僅要為放電產(chǎn)物提供足夠的存儲空間,還要為氧氣、電子、鋰離子提供正常傳輸?shù)耐ǖ��？锥氯⒄龢O極化導致電池容量降低、循環(huán)性能下降。為了改善鋰空氣電池放電產(chǎn)物堵塞空氣正極,提高鋰空氣電池循環(huán)性能。本文提出將碳納米管CNT和KB混合制備鋰空氣電池正極。通過改變碳納米管CNT和KB混合質(zhì)量比,制備一系列碳納米管CNT和Ketjen Black carbon(KB)混合空氣正極,對相應(yīng)的鋰空氣電池進行電化學性能測試,探究電池的循環(huán)性,并對充放電產(chǎn)物及反應(yīng)機理進行初步的探索。1、CNT、N-CNT及KB材料具有高的電導率、平均孔徑在3.5 nm左右,與鋰空氣電池放電產(chǎn)物沉積位置的孔徑相當,除此KB碳多孔材料含有大量的中孔,總的孔體積高達2.79 m3/g,比表面積也高達1589.92 m2/g。碳納米管的加入可以有效增加反應(yīng)的活性位點,提高氧氣和離子的傳輸效率。采用合適的比例將KB與碳納米管材料混合可以制備得到具有較大比表面積和孔體積的空氣正極,為鋰空氣電池提供更多放電產(chǎn)物存儲場所以及最佳的氣液擴散通道,從而提高電池的電化學性能和循環(huán)性能。2、在干燥的空氣環(huán)境中,以1:1比例CNT/KB(KB:CNT:PTFE為4.5:4.5:1)混合的空氣正極,對鋰空氣電池的能量效率最有利,且循環(huán)性能最好。碳納米管CNT與KB按1:1混合,充分發(fā)揮了各自的優(yōu)勢,形成了適應(yīng)于鋰空氣電池的正極結(jié)構(gòu),為放電產(chǎn)物提供了足夠的存儲空間,保障了氧氣和離子在正極內(nèi)部的傳輸,提高了電池的電化學穩(wěn)定性。最終本實驗獲得了在0.3 m A/cm2條件下,容量高達0.4 m Ah,比容量為1000m Ah/g,穩(wěn)定循環(huán)186圈的大電流,高容量和高循環(huán)性能的鋰空氣電池。3、本文制備的鋰空氣電池均以1M Li TFSI/Sulfolane作為電解液,大部分電池在0.3 m A/cm2,甚至在0.5 m A/cm2的電流密度下均可以循環(huán)上百圈,說明環(huán)丁砜體系的電解液是一種較為穩(wěn)定的電解液,可以抵御電池較高的過電勢,真正建立鋰空氣電池可逆循環(huán),是一種適用于鋰空氣電池的電解液。4、環(huán)丁砜體系的鋰空氣電池放電時,正極表面覆蓋很多的薄片狀的過氧化鋰產(chǎn)物,充電過程中過氧化鋰又隨之分解。但是由于過氧化鋰導電性較差,分解電壓較高,放電產(chǎn)物并不會完全分解。隨著放電產(chǎn)物逐漸的積累,正極孔道被堵塞,造成正極鈍化電池衰竭。因此深入正極研究,構(gòu)造合適的多孔結(jié)構(gòu),降低空氣正極極化是提高鋰空氣電池性能的重要途徑。
[Abstract]:The theoretical energy density of lithium-air batteries is as high as 11425 Wha / kg (excluding oxygen. Compared with lithium-ion batteries, fuel cells and air batteries, it is the largest energy storage system so far and has attracted the attention of researchers all over the world. The research and development of high-energy lithium-air batteries is expected to solve the global energy shortages, environmental pollution, soaring oil prices and energy wars, especially for the long distance driving of electric vehicles, providing a new way to achieve. In lithium-air batteries, the air cathode is the main place for redox reaction and for the discharge products. It not only provides enough storage space for the discharge products, but also provides the normal transmission channels for oxygen, electrons and lithium ions. The cell capacity is reduced and the cycle performance is decreased due to the hole blockage and positive polarization. In order to improve the performance of lithium-air battery, the discharge product can block the positive electrode of air and improve the performance of lithium air battery. In this paper, carbon nanotube (CNT) and KB were mixed to prepare the cathode of lithium air battery. A series of carbon nanotube (CNT) and Ketjen Black carbonated air positive electrodes were prepared by changing the mixing mass ratio of carbon nanotubes (CNT) and KB. The electrochemical properties of the corresponding lithium air batteries were tested to explore the recirculation of the batteries. The charge-discharge products and reaction mechanism were preliminarily explored. The CNTN-CNT and KB materials had high electrical conductivity and the average pore size was about 3.5 nm, which was equivalent to the pore size of the deposition position of the discharge products of the lithium air battery. In addition, this KB carbon porous material contains a large number of mesoporous materials, the total pore volume is up to 2.79m3 / g, and the specific surface area is up to 1589.92 m2 / g. The addition of carbon nanotubes can effectively increase the active sites of the reaction and improve the transport efficiency of oxygen and ions. Air positive electrodes with large specific surface area and pore volume can be prepared by mixing KB with carbon nanotube materials in a suitable proportion, which provides more storage places for discharge products and the best gas-liquid diffusion channel for lithium air batteries. Therefore, the electrochemical performance and cycle performance of the battery are improved. In the dry air environment, the air positive electrode mixed with CNT/KB(KB:CNT:PTFE at 1:1 ratio is the most favorable to the energy efficiency of the lithium air battery, and its cycling performance is the best. The carbon nanotubes (CNT) and KB are mixed at 1:1 to give full play to their respective advantages and form a positive electrode structure suitable for lithium air batteries, which provides sufficient storage space for the discharge products and ensures the transport of oxygen and ions in the positive electrode. The electrochemical stability of the battery is improved. Finally, under the condition of 0.3 m A/cm2, the lithium air battery with a capacity of up to 0.4 m Ahh, a specific capacity of 1000m Ah/ g, a large current with a steady cycle of 186 cycles, a high capacity and high cycling performance is obtained. The lithium air battery prepared in this paper uses 1 M Li TFSI/Sulfolane as the electrolyte. Most batteries can cycle hundreds of cycles at a current density of 0. 3 Ma / cm ~ 2, or even 0. 5 m A/cm2, indicating that the electrolyte in the sulfolane system is a relatively stable electrolyte that can withstand the higher overpotential of the battery. The real establishment of a reversible cycle for lithium-air batteries is a product of lithium oxide, a thin sheet of lithium oxide coated on the surface of the positive electrode, which is suitable for lithium air batteries in the system of sulfolane. Lithium oxide decomposes again during charging. However, due to the poor conductivity of lithium oxide and high decomposition voltage, the discharge products will not be completely decomposed. With the gradual accumulation of discharge products, the positive electrode channel is blocked, resulting in positive passivation battery failure. Therefore, it is an important way to improve the performance of lithium-air battery by studying the positive electrode, constructing the appropriate porous structure and reducing the polarization of the air positive electrode.
【學位授予單位】：深圳大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TM911.41;O646.541

【參考文獻】

相關(guān)期刊論文 前3條

1 武巍;田艷艷;高軍;楊勇;;碳材料在鋰空氣電池中的應(yīng)用及研究進展[J];電源技術(shù);2012年04期

2 明博;韓虹羽;;鋰離子電池正極材料進展[J];化工生產(chǎn)與技術(shù);2012年04期

3 王芳;梁春生;徐大亮;曹慧群;孫宏元;羅仲寬;;鋰空氣電池的研究進展[J];無機材料學報;2012年12期

相關(guān)碩士學位論文 前1條

1 付正浩;高比能量鋰/空氣電池的研究[D];復(fù)旦大學;2012年

，

本文編號：1840542