本文選題：鋰離子電池 + 正極材料　； 參考：《天津大學(xué)》2014年博士論文

【摘要】：作為新能源的鋰離子電池具有比能量高、體積小、質(zhì)量輕、可高速率放電、自放電率低、循環(huán)壽命長、無毒等優(yōu)異性,自問世以來就受到極大的關(guān)注。目前,尋找可替代的新能源以及可用于儲能的新材料已經(jīng)成為人們進行科學(xué)研究的重點之一,其中鋰離子電池正極材料顯得尤為重要。尖晶石型Li Mn_2O_4材料具有原料資源豐富、易制備和環(huán)境友好等優(yōu)點,成為鋰離子電池領(lǐng)域研究的熱點。另外,Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O_2是一種極具應(yīng)用前景的新型鋰離子電池正極材料,它具有安全性高和低成本的優(yōu)勢。因此探索方便易行,環(huán)境友好的新型制備方法,對促進其實用化具有重要意義。本文采用低溫水熱前驅(qū)體法和低溫環(huán)己酮水熱制備尖晶石LiMn_2O_4,并且詳細研究了影響低溫環(huán)己酮水熱法制備的LiMn_2O_4的各個因素。此外,采用簡單兩步法合成了三元材料Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O_2,并對其影響因素進行了初步的探討。通過X射線粉末衍射(XRD)、掃描電鏡(SEM)等測試手段對樣品的結(jié)構(gòu)和形貌進行表征,對采用不同方法合成的正極材料的合成條件進行了研究,利用首次充放電和循環(huán)性能測試,來考察材料的電化學(xué)性能。通過研究發(fā)現(xiàn),在低溫前驅(qū)體法中,水熱反應(yīng)溫度120℃,加熱12 h,然后在100℃,干燥12 h,得到前驅(qū)體β-MnO_2粉末,最后在800℃,煅燒10 h合成的LiMn_2O_4性能最佳。采用低溫環(huán)己酮水熱法,水熱溫度110℃,反應(yīng)8 h,同時控制Li/Mn的摩爾比為1.1:1,以及環(huán)己酮與蒸餾水的比為2:25時,此時制備出的樣品尖晶石LiMn_2O_4具有最優(yōu)的電化學(xué)性能。合成三元材料Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O_2的最優(yōu)條件為:在60℃,制備出前驅(qū)體Ni_(1/3)Co_(1/3)Mn_(1/3)(OH)2,在Ar氣保護下,混合一定比例的LiOH·H2O,通氣,先加熱450℃預(yù)燒4 h,然后在850℃煅燒6 h。盡管尖晶石LiMn_2O_4有很多優(yōu)點,但是它的導(dǎo)電性差限制了它在在大功率應(yīng)用程序中的使用。另外,正極材料LiMn_2O_4在循環(huán)過程中存在嚴重的容量衰減,則是另一個具有挑戰(zhàn)性的問題,同時也是阻礙了LiMn_2O_4的商業(yè)化。因此,必須對LiMn_2O_4進行改性。碳包覆是一種有效的改性手段,可以改善活性物質(zhì)顆粒之間以及活性物質(zhì)與導(dǎo)電劑之間的導(dǎo)電性。文中利用XRD、SEM、電化學(xué)測試等手段研究不同碳源、碳包覆量、煅燒溫度等因素對合成產(chǎn)品各種性能的影響,研究結(jié)果表明針對低溫環(huán)己酮水熱法,葡萄糖為最佳碳源,添加10%的葡萄糖,在600℃煅燒4 h合成的LiMn_2O_4/C具有最好的電化學(xué)性能。
[Abstract]:As a new energy source, lithium ion batteries have many advantages, such as high specific energy, small volume, light weight, high rate of discharge, low self-discharge rate, long cycle life, non-toxic and so on. At present, the search for new energy sources and new materials for energy storage has become one of the focuses of scientific research, among which the cathode materials for lithium ion batteries are particularly important. Spinel Li Mn_2O_4 has become a hotspot in the field of lithium-ion batteries due to its rich raw material resources, easy preparation and environmental friendliness. In addition, this new type of cathode material for lithium-ion batteries has the advantages of high safety and low cost. Therefore, it is of great significance to explore a new and convenient and environmentally friendly preparation method to promote its practicality. In this paper, spinel limn _ 2O _ 4 was prepared by low-temperature hydrothermal precursor method and low-temperature cyclohexanone hydrothermal method. The factors affecting the preparation of LiMn_2O_4 by low-temperature cyclohexanone hydrothermal method were studied in detail. In addition, a simple two-step method was used to synthesize the ternary material Lian Nihe / T 1 / 3 Cos / T / 1 / 3 / 3 / 1 / 3 / 3 / 1 / 3 / 3 / 1 / 3 / 3 / 1 / 3 / 1 / 3 / 3 / 1 / 3 / 1 / 3 / 1 / 3 / 1 / 3 / 1 / 3 / 3 The structure and morphology of the samples were characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The synthetic conditions of the cathode materials synthesized by different methods were studied. To investigate the electrochemical properties of the materials. It was found that the precursor 尾 -MnO _ 2 powder was obtained by hydrothermal reaction at 120 鈩，

本文編號：1938955