本文選題：鋰離子電池　切入點(diǎn)：負(fù)極材料　出處：《華中師范大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：石墨是重要的鋰離子電池負(fù)極材料,在充放電時(shí),它會(huì)與電解液發(fā)生溶劑化反應(yīng),因而使其體積發(fā)生膨脹,甚至導(dǎo)致石墨層脫落。進(jìn)而影響其電化學(xué)性能。石墨的理論比容量為372mAh/g,但實(shí)際比容量只有330mAh/g,循環(huán)性能也很差,大電流充放電時(shí)容量衰減很快�；谶@些缺點(diǎn),它已不能滿足一些電子產(chǎn)品的快速發(fā)展需求。石墨烯具有大的比表面積、大容量且具有很好的化學(xué)和熱穩(wěn)定性。因此可以用石墨烯包覆石墨,這樣可以防止石墨發(fā)生脫落,保持其完整性,進(jìn)而提高石墨材料的電化學(xué)性能。 本論文選用湖州創(chuàng)亞動(dòng)力電池材料有限公司生產(chǎn)的石墨(G1620)和常州中科來(lái)方能源科技有限公司生產(chǎn)的石墨(G123)作為原材料,采用機(jī)械球磨、石墨烯包覆及高溫?zé)徇�原等改性手段制備了一系列石墨烯含量的rGO/G1620和rGO/G123材料。利用X射線衍射(XRD)、掃描電子顯微鏡(SEM)、恒流充放電和循環(huán)伏安等測(cè)試方法系統(tǒng)地考察了石墨烯含量對(duì)rGO/G1620和rGO/G123材料的結(jié)構(gòu)、形貌以及電化學(xué)性能的影響。 通過(guò)XRD測(cè)試,發(fā)現(xiàn)石墨烯包覆后對(duì)G1620和G123材料的結(jié)構(gòu)影響不大。進(jìn)行SEM掃描,可以看出有石墨烯包覆在G1620和G123材料表面。循環(huán)伏安測(cè)試則說(shuō)明石墨烯包覆可以提高了石墨材料的容量。 在10mA/g的電流密度,0.005-2V電壓范圍內(nèi)進(jìn)行恒流充放電測(cè)試,對(duì)于石墨烯包覆G1620材料,石墨烯含量為3%的材料具有更高的容量和更好的循環(huán)性能,其首次放電和充電比容量分別為482mAh/g和388mAh/g高于G1620材料的388mAh/g和340mAh/g,其庫(kù)倫效率達(dá)到80%。30次循環(huán)后,其充電比容量仍然可以達(dá)到385mAh/g而G1620材料只有79mAh/g,其容量的保留率高達(dá)99.5%. 相同的測(cè)試條件下,對(duì)于石墨烯包覆后的G123材料,石墨烯含量為4%的材料具有更高的容量和更好的循環(huán)性能,其首次放電和充電比容量為510mAh/g和393mAh/g大于G123材料的400mAh/g和357mAh/g,其庫(kù)倫效率為77%。30次循環(huán)后,其充電比容量仍然可以到達(dá)387mAh/g,然而G123材料只能達(dá)到252mAh/g,其保留率高達(dá)98.5%。 石墨烯包覆可以提高石墨材料的容量以及循環(huán)性能。利用本論文改性方法制備的鋰離子電池G1620和G123負(fù)極材料有大容量、循環(huán)性能好等特點(diǎn)。
[Abstract]:Graphite is an important anode material for lithium-ion batteries. During charging and discharging, graphite reacts with the electrolyte in solvation, thus causing its volume to expand. The theoretical specific capacity of graphite is 372mAh / g, but the actual specific capacity is only 330mAh/ g, the cycle performance is very poor, and the capacity of high current charge-discharge decays rapidly. Graphene has large specific surface area, large capacity and good chemical and thermal stability. Therefore, graphene can be coated with graphene to prevent graphite from falling off. The integrity of graphite is maintained and the electrochemical properties of graphite are improved. In this paper, the graphite G1620 produced by Huzhou Chuangya Power Battery material Co., Ltd and the graphite G123 produced by Changzhou Zhongkelaifang Energy Technology Co., Ltd. A series of rGO/G1620 and rGO/G123 materials with graphene content were prepared by means of graphene coating and high temperature thermal reduction. The methods of X-ray diffraction (XRD), scanning electron microscopy (SEM), constant current charge-discharge and cyclic voltammetry were systematically investigated. The structure of rGO/G1620 and rGO/G123 materials with graphene content was studied. Effects of morphology and electrochemical properties. The results of XRD test showed that graphene coating had little effect on the structure of G1620 and G123. SEM scanning was carried out. It can be seen that graphene is coated on the surface of G1620 and G123, and cyclic voltammetry shows that graphene coating can increase the capacity of graphite. Constant current charge-discharge tests were carried out in the current density range of 0.005-2V at 10 Ma / g. For graphene coated G1620 materials, the graphene content of 3% has higher capacity and better cycling performance. The initial discharge and charging capacity of G1620 are 482mAh/ g and 388mAh/ g, respectively, which are higher than those of G1620 material (388mAh/ g and 340mAh/ g). After the Coulomb efficiency reaches 80.30 cycles, the charge specific capacity can still reach 385mAhg / g, while the G1620 material has only 79mAh/ g, and its capacity retention rate is 99.55.The ratio of the first discharge and charging capacity of G1620 is 99.5mg. Under the same test conditions, for the G123 material coated with graphene, the material with 4% graphene content has higher capacity and better cycling performance. The initial discharge and charge specific capacity of 510mAh/ g and 393mAh/ g is greater than that of G123's 400mAh/ g and 357mAh/ g, and its Coulomb efficiency is 77.30 cycles, and its charge specific capacity can still reach 387mAh-g. however, G123 material can only reach 252mAh/ g, and its retention rate is 98.5B. Graphene coating can improve the capacity and cyclic performance of graphite materials. The G1620 and G123 anode materials of Li-ion batteries prepared by the modified method in this paper have the characteristics of large capacity and good cycling performance.
【學(xué)位授予單位】：華中師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：O613.71;TM912

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本文編號(hào)：1605107