本文選題：三維結(jié)構(gòu)　切入點(diǎn)：石墨烯　出處：《上海應(yīng)用技術(shù)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來,鋰離子電池得到了廣泛的研究和長足的發(fā)展,但是在電動(dòng)交通工具、便攜式電子設(shè)備、柔性可穿戴電子設(shè)備等領(lǐng)域還沒有達(dá)到人們的期望值。這主要是因?yàn)檎龢O材料價(jià)格偏高、比容量偏低,并可能產(chǎn)生一定的安全問題;負(fù)極材料主要是碳材料,其比容量有限,用量較大,若能提升負(fù)極材料的比容量,即可大大提高電池的性能并減輕電池的重量和體積;另外現(xiàn)有的電極技術(shù)還不能使鋰離子電池很好的應(yīng)用于柔性器件等領(lǐng)域。因此發(fā)展高比容量、高倍率性能的正極材料,開發(fā)新型的高性能負(fù)極材料,以及發(fā)展新型的電池技術(shù)是未來鋰離子電池發(fā)展的重要方向。大量研究表明,將石墨烯(碳)材料與正負(fù)極材料復(fù)合,構(gòu)建三維結(jié)構(gòu)復(fù)合材料被證實(shí)能夠有效改善電極材料的電化學(xué)性能。因此,開發(fā)行之有效的制備方法以實(shí)現(xiàn)石墨烯(碳)與正負(fù)極材料之間的有機(jī)結(jié)合,是該領(lǐng)域研究的關(guān)鍵。有鑒于此,本研究設(shè)計(jì)并制備了三類石墨烯(碳)三維結(jié)構(gòu),分別實(shí)現(xiàn)了其與磷酸鐵鋰正極材料和紅磷負(fù)極材料的原位復(fù)合,并對(duì)合成材料的制備過程、物理性質(zhì)、電化學(xué)性能及部分組分間的協(xié)同效應(yīng)進(jìn)行了研究和探索。本文中開創(chuàng)了新的磷酸鐵鋰制備方法,以水熱法實(shí)現(xiàn)了其與石墨烯的原位復(fù)合,得到了三維石墨烯/磷酸鐵鋰(G/LiFePO4)復(fù)合正極材料。0.2 C時(shí)放電容量為較高的160 mAh/g,且具有良好的倍率性能(10C時(shí)放電比容量達(dá)到115mAh/g)和循環(huán)穩(wěn)定性(1 C時(shí)100次循環(huán)的容量保持率為94.2 %)。通過引入三維CVD石墨烯基底,制備了三維石墨烯/磷酸鐵鋰/石墨烯(3DG/LFP/G)復(fù)合正極材料,進(jìn)一步提高了材料的電化學(xué)性能:0.2 C時(shí)容量達(dá)到164 mAh/g,10 C時(shí)容量達(dá)到124 mAh/g,1 C下100次循環(huán)的容量保持率為95.7 %。交流阻抗分析證明了 3DG/LFP/G比G/LiFePO4具有更優(yōu)異的動(dòng)力學(xué)特性(更小的電荷轉(zhuǎn)移阻抗、更高的鋰離子擴(kuò)散系數(shù))。負(fù)極方面,以碳化法制備出電化學(xué)性能優(yōu)異的柔性碳布,以此為基底,通過蒸氣-冷凝法實(shí)現(xiàn)了紅磷的負(fù)載,制備出柔性的紅磷/碳布(P/C)復(fù)合負(fù)極材料,0.1 C時(shí)放電比容量為1063 mAh/g,隨后通過氧化石墨烯(GO)包覆處理,得到了具有“三明治”結(jié)構(gòu)的GO/P/C復(fù)合材料,容量提高到1100 mAh/g,同時(shí)其200次循環(huán)的容量保持率提升了 13.1 %,顯示出了更好的電化學(xué)性能。本研究不僅為新型高倍率動(dòng)力鋰離子電池磷酸鹽系正極材料的開發(fā)提供了有效的技術(shù)途徑,同時(shí)開發(fā)了高性能的負(fù)極材料并初步研究了其作為柔性電池材料的可行性,具有重要的實(shí)際意義和學(xué)術(shù)價(jià)值。
[Abstract]:In recent years, lithium ion batteries have been widely studied and developed, but in electric vehicles, portable electronic devices, Flexible wearable electronics and other fields have not yet met expectations. This is mainly due to the high price of cathode materials, low specific capacity, and may cause certain safety problems; negative materials are mainly carbon materials, whose specific capacity is limited. If the specific capacity of the anode material can be increased, the performance of the battery can be greatly improved and the weight and volume of the battery can be reduced. In addition, the existing electrode technology can not make lithium ion batteries well used in flexible devices and other fields. Therefore, the development of high specific capacity, high rate performance cathode materials, the development of new high performance anode materials, And the development of new battery technology is an important direction for the development of lithium-ion batteries in the future. A large number of studies show that graphene (carbon) materials are combined with cathode and cathode materials. It has been proved that the electrochemical properties of electrode materials can be improved effectively by constructing three-dimensional structure composites. Therefore, an effective preparation method is developed to realize the organic binding between graphene (carbon) and cathode materials. In view of this, three kinds of graphene (carbon) three-dimensional structures were designed and prepared, and in situ recombination with lithium iron phosphate cathode material and red phosphorus negative electrode material were realized respectively, and the preparation process of the synthesized materials was also studied. The physical properties, electrochemical properties and synergistic effects among some groups have been studied and explored. In this paper, a new preparation method of lithium ferric phosphate has been developed, and in situ recombination with graphene has been realized by hydrothermal method. Three-dimensional graphene / LiFePO4 composite cathode material with high discharge capacity of 160mAh/ g was obtained at 0.2C, and its specific discharge capacity reached 115mAh/ g at 10C with good performance, and the capacity of 100 cycles at 1 C cycle stability was maintained. The holdup is 94. 2%. By introducing three dimensional CVD graphene substrates, Three dimensional graphene / lithium iron phosphate / graphene 3 DG / LFP / G composite cathode materials were prepared. The electrochemical performance of the material was further improved when the capacity of the material reached 164mAh/ g ~ (-1) C at a capacity of 164mAh/ g ~ (-1) C, and the capacity retention rate of 100 cycles at 124mAh/ g ~ (-1) C was 95.7%. Ac impedance analysis proved that 3DG / L _ (FPP) _ G had better kinetic properties than that of G _ (P) LiFePO _ 4. (smaller charge transfer impedance, For a higher diffusion coefficient of lithium ion, a flexible carbon cloth with excellent electrochemical performance was prepared by carbonation method, which was used as the substrate to realize the loading of red phosphorus by vapor-condensation method. A flexible red phosphorus / carbon cloth P / C composite negative electrode material with a specific discharge capacity of 1063 mAh/ g at 0.1 C was prepared, and then coated with graphene oxide (GOO) to obtain a "sandwich" structure GO/P/C composite. At the same time, the capacity retention rate of 200 cycles increased by 13.1%, showing better electrochemical performance. This study not only provides a new type of phosphate cathode materials for high-rate power lithium ion batteries, but also provides a basis for the development of phosphate cathode materials for high-rate power lithium-ion batteries. An effective technical approach, At the same time, the high performance negative electrode material is developed and its feasibility as flexible battery material is preliminarily studied, which has important practical significance and academic value.
【學(xué)位授予單位】：上海應(yīng)用技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ127.11;TM912

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相關(guān)期刊論文 前2條

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本文編號(hào)：1638640