【摘要】：隨著電動(dòng)自行車和新能源汽車產(chǎn)業(yè)發(fā)展步伐的不斷加快,儲(chǔ)能科技迅速受到越來(lái)越多人的關(guān)注,綠色能源產(chǎn)業(yè)對(duì)鋰離子電池的要求和關(guān)注度已達(dá)到了歷史最高點(diǎn)。鋰離子電池已成為目前最被看好的動(dòng)力電源。其中,正極材料對(duì)鋰離子電池的性能起到了關(guān)鍵的作用。橄欖石結(jié)構(gòu)的磷酸鐵鋰因其價(jià)格低廉,無(wú)毒,較高的理論比容量,優(yōu)異的熱穩(wěn)定性和平穩(wěn)的放點(diǎn)平臺(tái)等優(yōu)點(diǎn),成為極具潛力的鋰離子電池正極材料,成為近年來(lái)開發(fā)研究的熱點(diǎn)。 本論文首先綜述了鋰離子電池的一些基本特點(diǎn)和工作原理等,通過(guò)分析目前磷酸鐵鋰的合成過(guò)程中存在的一些問(wèn)題,提出了一種在常壓和低溫的液相環(huán)境下直接快速合成粒徑小而均勻的并具有橄欖石結(jié)構(gòu)的磷酸鐵鋰的新方法。以二甲亞砜/水溶液作為反應(yīng)介質(zhì),在常壓和較低溫度的條件下,經(jīng)過(guò)很短的反應(yīng)時(shí)間即可直接制得粒徑小且分布均勻的單一相橄欖石結(jié)構(gòu)的磷酸鐵鋰。將液相直接的得到的磷酸鐵鋰混合少量的葡萄糖在高溫下短時(shí)間燒結(jié),可以得到電化學(xué)性能優(yōu)異的LiFePO_4/C。本文利用掃描電鏡(SEM)、X射線衍射(XRD)、透射電鏡(TEM)、紅外光譜(IR)、電性能測(cè)試等對(duì)樣品的表觀形貌、粒徑大小和晶體結(jié)構(gòu)、電化學(xué)性能等進(jìn)行了表征,通過(guò)對(duì)不同反應(yīng)物濃度,反應(yīng)時(shí)間,溶劑二甲基亞砜與水的比值,燒結(jié)時(shí)間,燒結(jié)溫度條件下合成出的樣品進(jìn)行對(duì)比,得出了制備LiFePO_4/C材料的最優(yōu)化條件。并將液相法直接制得的LiFePO_4和最優(yōu)化條件下制得的LiFePO_4/C進(jìn)行對(duì)比和分析,說(shuō)明一定量的碳包覆和短時(shí)間的熱處理對(duì)于磷酸鐵鋰電化學(xué)性能的提高是非常重要的。
[Abstract]:With the rapid development of electric bicycle and new energy automobile industry, more and more people pay attention to energy storage technology. The demand and attention of green energy industry for lithium ion battery has reached the highest point in history. Lithium ion battery has become the most promising power supply. Among them, cathode material plays a key role in the performance of lithium ion battery. Olivine structure lithium iron phosphate has become a potential cathode material for lithium-ion batteries because of its low price, non-toxic, high theoretical specific capacity, excellent thermal stability and stable placement platform. It has become a hot spot in recent years. In this paper, some basic characteristics and working principles of lithium ion battery are reviewed, and some problems existing in the synthesis of lithium iron phosphate are analyzed. A new method for the direct and rapid synthesis of lithium ferric phosphate with small and uniform particle size and olivine structure in liquid environment at atmospheric pressure and low temperature was proposed. Using dimethyl sulfoxide / aqueous solution as the reaction medium, lithium ferric phosphate with small particle size and uniform distribution of olivine structure can be prepared directly through a very short reaction time under the condition of atmospheric pressure and low temperature. LiFePO _ 4 / C _ (4) / C with excellent electrochemical performance can be obtained by sintering a small amount of glucose at high temperature by mixing lithium ferric phosphate directly with liquid phase. The apparent morphology, particle size, crystal structure and electrochemical properties of the samples were characterized by scanning electron microscope (SEM), X-ray diffraction (SEM), (XRD), transmission electron microscopy (XRD), (TEM), infrared spectroscopy (IR), and electrochemical properties. The ratio of solvent dimethyl sulfoxide to water, sintering time and sintering temperature were compared, and the optimum conditions for the preparation of LiFePO_4/C materials were obtained. The comparison and analysis between the LiFePO_4 prepared by liquid phase method and the LiFePO_4/C prepared under optimum conditions show that a certain amount of carbon coating and short time heat treatment are very important for improving the electrochemical performance of lithium iron phosphate.
【學(xué)位授予單位】：河南師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2011
【分類號(hào)】：TM912

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