本文選題：二氧化錫 + 三氧化二鐵　； 參考：《南京航空航天大學(xué)》2014年博士論文

【摘要】：鋰離子電池具有高開路電壓、低自放電率、較長的循環(huán)壽命、高比能量、無記憶效應(yīng)等特點,被稱為二十一世紀(jì)的綠色能源和主導(dǎo)電源,具有廣泛的應(yīng)用前景。而鋰離子電池的性能主要取決于正極材料、負(fù)極材料以及電解質(zhì)材料的結(jié)構(gòu)和性能,開發(fā)廉價高性能的正、負(fù)極材料一直是近年來研究的熱點。針對負(fù)極材料來說,目前商業(yè)化的負(fù)極材料以石墨類為主,但石墨的理論容量只有372 m A h/g,已無法滿足高能量鋰離子電池的需求。因此,開發(fā)容量更高、更安全的新型負(fù)極材料具有重大的意義。在眾多的負(fù)極材料當(dāng)中,Sn O2和Fe2O3是兩種極具潛力的材料。但由于這些氧化物的導(dǎo)電性很差,并且在充放電過程中,隨著鋰離子的嵌入和脫出,Sn O2和Fe2O3會產(chǎn)生巨大的體積變化,導(dǎo)致材料的粉化,造成材料的容量迅速衰減。如何提高這些氧化物的循環(huán)性能也成為了該領(lǐng)域的一個重要課題。既然碳材料具有很好的循環(huán)性能,而氧化物材料具有較高的比容量,如果能把碳材料和氧化物結(jié)合起來,發(fā)揮二者的優(yōu)勢,彌補(bǔ)單一材料所具有的缺陷,就有可能獲得高容量、循環(huán)性能良好的負(fù)極材料。本文采用不同的方法制備了Sn O2/graphene、Sn O2/FGS、Sn O2/MCNF以及Fe2O3/MCNF、Fe2O3/carbon foam復(fù)合材料,研究了孔隙度、負(fù)載量、電流密度及不同載體等因素對產(chǎn)物電化學(xué)性能的影響。(1)采用原位合成的方法,以Sn Cl2?2H2O為錫源,以氧化石墨(GO)為基體,以極性較弱的乙醇作為溶劑,通過Sn2+與氧化石墨之間的氧化還原反應(yīng),制備了具有多孔結(jié)構(gòu)的Sn O2/graphene復(fù)合材料。多孔結(jié)構(gòu)的存在,有利于電解液的傳輸和電荷的轉(zhuǎn)移;石墨烯的存在,一方面為Sn O2提供了良好的導(dǎo)電網(wǎng)絡(luò),另一方面能夠?qū)n O2的體積變化起到緩沖的作用。電化學(xué)測試結(jié)果表明,復(fù)合物電極材料表現(xiàn)出良好的電化學(xué)性能。(2)以Sn Cl2·2H2O和GO為原料,在未加入任何添加劑的情況下,通過水熱合成的方法制備了Sn O2/graphene復(fù)合物,討論了不同負(fù)載量復(fù)合物的電化學(xué)性能以及材料微孔孔隙度對產(chǎn)物性能的影響,結(jié)果表明,微孔孔隙度較高的樣品表現(xiàn)出較好的電化學(xué)性能,這是因為微孔的存在能夠提供較高的活性面積。采用微波的方法對水熱合成進(jìn)行了改進(jìn),將反應(yīng)時間縮短至2 min,研究了微波反應(yīng)時間對產(chǎn)物性能的影響,結(jié)果表明,微波時間為2 min左右時,原料已經(jīng)完全反應(yīng),大大縮短了復(fù)合物的制備時間。(3)將文獻(xiàn)所述的方法加以改進(jìn),制備了高比表面積的介孔碳納米纖維(MCNF)陣列,MCNF具有很高的比表面積,較大的孔容量和石墨化結(jié)構(gòu),是一種優(yōu)良的載體;采用低溫下硝酸鹽熱分解的方法制備了Fe2O3/MCNF復(fù)合材料,并研究了其作為鋰離子電池負(fù)極材料的電化學(xué)性能,討論了復(fù)合物的特殊結(jié)構(gòu)對復(fù)合物性能的影響,實驗結(jié)果表明,Fe2O3/MCNF復(fù)合物電極表現(xiàn)出優(yōu)異的電化學(xué)性能,這是由于:樣品的介孔孔道能夠為Fe2O3納米粒子的體積變化提供緩沖的空間;相互連通的孔道有利于Fe2O3與電解液充分接觸。采用相同的方法制備了Fe2O3/carbon foam復(fù)合材料,研究了其電化學(xué)性能,并與Fe2O3/MCNF復(fù)合材料進(jìn)行了對比。(4)采用熱剝離GO的方法制備了官能團(tuán)含量不同的兩種功能化石墨烯:FGS300和FGS900,采用簡單的水熱合成,在沒有任何添加劑的情況下,僅利用Sn Cl4·5H2O的水解制備了Sn O2/FGS復(fù)合物,研究了其電化學(xué)儲鋰性能,并討論了官能團(tuán)對產(chǎn)物性能的影響。實驗結(jié)果表明,Sn O2/FGS900復(fù)合物電極在較小的電流密度下能夠表現(xiàn)出較好的電化學(xué)性能,而當(dāng)在大電流密度下進(jìn)行循環(huán)測試時,Sn O2/FGS300卻能表現(xiàn)出更好的電化學(xué)性能。通過低溫熔融-水解-煅燒的方法來制備Sn O2/MCNF復(fù)合物,并研究了其電化學(xué)性能。測試結(jié)果顯示,復(fù)合物保持了MCNF的雙介孔結(jié)構(gòu),并表現(xiàn)出良好的循環(huán)性能。
[Abstract]:Lithium ion batteries have the characteristics of high open circuit voltage, low self discharge rate, long cycle life, high specific energy and no memory effect. It is known as the green energy and leading power in twenty-first Century. The performance of lithium ion batteries depends on the structure and properties of Yu Zheng polar materials, negative electrode materials and electrolyte materials. It has been a hot topic in recent years to develop cheap and high performance positive materials. For negative materials, commercialized negative materials are mainly graphite, but the theoretical capacity of graphite is only 372 m A h/g, so it is unable to meet the needs of high energy lithium ion batteries. Therefore, a new type of negative electrode with higher capacity and safer capacity is developed. It is of great significance. Among the many negative materials, Sn O2 and Fe2O3 are two highly potential materials. But because of the poor conductivity of these oxides, and in the process of charging and discharging, with the insertion and removal of lithium ions, the Sn O2 and Fe2O3 will produce huge volume changes, resulting in the pulverization of the material and the rapid deterioration of the capacity of the materials. Reducing. How to improve the cycling performance of these oxides has also become an important topic in this field. Since carbon materials have good cycling performance and oxide materials have high specific capacity, it is possible to gain the advantages of the combination of carbon materials and oxides to make full use of the defects of the single material and to make up the defects of the two materials. Sn O2/graphene, Sn O2/FGS, Sn O2/MCNF and Fe2O3/MCNF, Fe2O3/carbon foam composites were prepared by different methods. The effects of porosity, load, current density and different carriers on the electrochemical properties of the products were studied in this paper. (1) in situ synthesis method, Sn C. L2? 2H2O is a tin source, with graphite oxide (GO) as the matrix and a weak polar ethanol as solvent. The porous structure of Sn O2/graphene composite is prepared through redox reaction between Sn2+ and graphite oxide. The existence of porous structure is beneficial to the transfer of electrolyte and the transfer of charge; the existence of graphene, on one hand, is Sn O2. A good conductive network is provided, on the other hand, the volume change of Sn O2 can be buffered. The electrochemical test results show that the composite electrode materials exhibit good electrochemical performance. (2) Sn O2/graphen is prepared by hydrothermal synthesis without adding any additives to Sn Cl2. 2H2O and GO as raw materials. The effects of the electrochemical properties of the composite with different load and the porosity of the material on the properties of the products were discussed. The results showed that the samples with higher porosity showed good electrochemical performance because the presence of micropores could provide a higher active area. The hydrothermal synthesis was carried out by microwave method. The reaction time was shortened to 2 min, and the effect of microwave reaction time on the performance of the product was studied. The results showed that when the microwave time was about 2 min, the raw material had been completely reacted and the preparation time of the complex was greatly shortened. (3) the methods described in the literature were improved and the high specific surface area of mesoporous carbon nanofibers (MCNF) arrays were prepared, M CNF has a high specific surface area, large pore volume and graphitization structure, which is a good carrier. Fe2O3/MCNF composites are prepared by thermal decomposition of nitrate at low temperature. The electrochemical properties of the composites as anode materials for lithium ion batteries are studied. The effects of the special structure of the complex on the properties of the composites are discussed. The results show that the Fe2O3/MCNF composite electrode shows excellent electrochemical performance, because the mesoporous channel of the sample can provide a buffer space for the volume change of Fe2O3 nanoparticles, and the interconnected channel is beneficial to the full contact between the Fe2O3 and the electrolyte. The same method is used to prepare the Fe2O3/carbon foam composite. The electrochemical properties were compared with the Fe2O3/MCNF composites. (4) two functional fossils of functional groups were prepared by thermal stripping GO: FGS300 and FGS900, using simple hydrothermal synthesis, and in the absence of any additives, the Sn O2/FGS complex was prepared by the hydrolysis of Sn Cl4. 5H2O only. The effect of functional group on the performance of the product is discussed. The experimental results show that the Sn O2/FGS900 composite electrode can show good electrochemical performance at a small current density, while Sn O2/ FGS300 can show better electrochemical performance when the current density is measured at a large current density. The Sn O2/MCNF complex was prepared by the method of temperature melting hydrolysis calcination, and its electrochemical properties were studied. The results showed that the compound retained the double mesoporous structure of MCNF and showed good cycling performance.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM912

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本文編號：1966084