本文關(guān)鍵詞： 鋰離子電池 三維自支撐結(jié)構(gòu) 納米線陣列 鈷基過渡金屬氧化物　出處：《合肥工業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鋰離子電池作為電化學(xué)能源儲(chǔ)存系統(tǒng)中應(yīng)用最為廣泛的新能源器件目前在能量密度和功率密度上仍有較大的提升空間。負(fù)極材料相對于正極材料而言在決定上述兩者的重要因素——比容量的提升上更具可行性,因此受到了大量的關(guān)注。而目前商用微米級(jí)塊狀負(fù)極材料由于其有限的電極動(dòng)力學(xué)與傳質(zhì)過程而逐漸逼近其性能的極限,所以納米結(jié)構(gòu)被大量引入到負(fù)極材料的設(shè)計(jì)之中,以期獲得更高的質(zhì)量比容量。納米電極結(jié)構(gòu)的引入可以通過縮短離子擴(kuò)散和電子傳輸路徑顯著改善電極動(dòng)力學(xué)過程,可以帶來諸如雙電層電容、贗電容等新型儲(chǔ)鋰機(jī)制,可以穩(wěn)定電極材料晶體結(jié)構(gòu)。當(dāng)然動(dòng)力學(xué)活性的增強(qiáng)不可避免地就會(huì)帶來熱力學(xué)穩(wěn)定性的減弱,納米電極也由此極容易受到外界環(huán)境溫度的干擾并趨向于團(tuán)聚。更值得注意的是,納米電極帶來的高比表面積會(huì)導(dǎo)致高表面副反應(yīng),嚴(yán)重降低電池的庫倫效率乃至于帶來安全上的隱患。此外有機(jī)粘結(jié)劑對于整合納米顆粒并連接納米顆粒與集流體是必不可少的,但是這些電子絕緣體的引入將會(huì)嚴(yán)重影響電極的導(dǎo)電性能和電極與集流體之間的界面過程。針對上述前兩個(gè)問題,微/納多級(jí)結(jié)構(gòu)和碳包覆被提出與應(yīng)用。而為了避免使用粘結(jié)劑,在集流體上直接生長的自支撐結(jié)構(gòu)被引入。在本文中,鑒于氧化鈷(Co_3O_4)擁有890 m Ah/g的理論比容量和尖晶石結(jié)構(gòu)方便于鋰通道的構(gòu)筑,因此通過水熱反應(yīng)的方法在三維網(wǎng)狀泡沫銅基底上生長納米結(jié)構(gòu)。但是作為過渡金屬氧化物,其儲(chǔ)鋰過程中轉(zhuǎn)換反應(yīng)機(jī)制所帶來的體積膨脹是不可忽視的,這會(huì)帶來較差的循環(huán)穩(wěn)定性。在此研究中,碳包覆和鎳、錳取代摻雜形成二元材料作為解決這一問題的兩條路徑并分別取得了不錯(cuò)的效果。通過碳包覆,三維氧化鈷納米線陣列電極在循環(huán)100圈之后達(dá)到了1484 m Ah/g的質(zhì)量比容量,容量保持率為100%。而鎳和錳取代摻雜分別形成鈷酸鎳和鈷酸錳二元鈷基三維納米線陣列,它們在容量和穩(wěn)定性上較氧化鈷而言都有較大的改善,但是鎳錳之間還是存在穩(wěn)定性的差異(鈷酸錳要優(yōu)于鈷酸鎳),這與它們傾向于占據(jù)尖晶石結(jié)構(gòu)A位還是B位的差異性有關(guān)。
[Abstract]:As the most widely used new energy devices in the electrochemical energy storage system, lithium ion battery still has a large space to improve the energy density and power density. The negative electrode material determines the above mentioned compared with the positive electrode material. The two important factors are more feasible than the increase of capacity. Because of its limited electrode dynamics and mass transfer process, commercial micron scale bulk anode materials are gradually approaching the limit of their performance. So nanostructures are introduced into the design of anode materials. The introduction of nano-electrode structure can significantly improve the electrode kinetic process by shortening ion diffusion and electron transport path, and can bring about such as double-layer capacitance. A new type of lithium storage mechanism such as pseudo-capacitance can stabilize the crystal structure of electrode materials. Of course the enhancement of kinetic activity will inevitably lead to the weakening of thermodynamic stability. As a result, nanocrystalline electrodes are easily disturbed by ambient temperature and tend to agglomerate. It is more important to note that the high specific surface area of nanometers will lead to high surface side effects. In addition, organic binder is essential to integrate nanoparticles and connect nanoparticles with fluid collection. However, the introduction of these electronic insulators will seriously affect the conductivity of the electrode and the interface process between the electrode and the collector. Micro / nano multistage structure and carbon coating are proposed and applied. In order to avoid the use of binder, self-supporting structure which grows directly on the collecting fluid is introduced. The theoretical specific capacity of 890m Ah/g and spinel structure are convenient for the construction of lithium channel. Therefore nanocrystalline structures were grown on a three-dimensional netted copper substrate by hydrothermal reaction. However as transition metal oxides the volume expansion caused by the transition reaction mechanism in the lithium storage process can not be ignored. In this study, carbon coating and nickel and manganese substitution for doping to form binary materials as two ways to solve this problem and achieved good results. The 3D cobalt oxide nanowire array electrode has a mass specific capacity of 1484 m Ah/g after 100 cycles. The capacity retention rate is 100. Nickel and manganese substituted doping form nickel cobaltate and manganese cobalt-based three-dimensional nanowire arrays respectively, which are better in capacity and stability than that in cobalt oxide. However, there is a difference in stability between nickel and manganese (manganese cobalt is superior to nickel cobalt, which is related to their tendency to occupy the A or B sites of spinel structure.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB383.1;TM912

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