本文選題：鋰離子電池　切入點(diǎn)：負(fù)極材料　出處：《天津工業(yè)大學(xué)》2017年碩士論文

【摘要】：近年來(lái),二氧化錫被視為最具有發(fā)展?jié)摿Φ男滦弯囯x子電池負(fù)極材料之一,但由于二氧化錫在首次充放電過(guò)程中體積膨脹高達(dá)50%以上,循環(huán)期間鋰離子的反復(fù)嵌入與脫嵌易出現(xiàn)粉化和團(tuán)聚現(xiàn)象,以至于二氧化錫電化學(xué)性能迅速下降,從而限制了它在鋰離子電池中的廣泛應(yīng)用,成為其應(yīng)用推廣的瓶頸。如何有效緩解二氧化錫在充放電過(guò)程中的體積效應(yīng)和粉化現(xiàn)象,提高電極的循環(huán)穩(wěn)定性已成為當(dāng)前研究二氧化錫負(fù)極材料的關(guān)鍵。目前,研究者們主要通過(guò)以下方式克服二氧化錫負(fù)極材料的局限性,并取得了很大的進(jìn)步。一是制備納米結(jié)構(gòu)的二氧化錫,如SnO_2納米薄片、SnO_2納米線、SnO_2納米陣列等,通過(guò)改變材料的形貌和減小材料顆粒尺寸來(lái)增加材料中的空隙率,從而在一定程度上能舒緩材料在充放電過(guò)程中帶來(lái)的體積效應(yīng)。二是構(gòu)建二氧化錫復(fù)合材料,如碳包覆、SnO_2-碳納米管復(fù)合、SnO_2-石墨烯復(fù)合等,通過(guò)在材料表面包覆無(wú)機(jī)或有機(jī)物質(zhì)來(lái)限制充放電過(guò)程中體積效應(yīng)對(duì)材料結(jié)構(gòu)和性能的破壞。本文采用水熱法合成SnO_2材料,通過(guò)研究表明,SnO_2納米片的電化學(xué)性能最佳。在此基礎(chǔ)上,本文從以下三個(gè)方面對(duì)SnO_2納米片進(jìn)行了改性研究。1.對(duì)SnO_2納米片與氧化石墨烯進(jìn)行了復(fù)合,制備了不同氧化石墨烯含量的SnO_2/石墨烯納米復(fù)合材料。研究結(jié)果表明:氧化石墨烯含量為50%的SnO_2/石墨烯納米復(fù)合材料的循環(huán)性能最佳,在160mA/g的電流密度下,經(jīng)過(guò)100次循環(huán)后,放電比容量維持在636.2mAh/g。2.對(duì)SnO_2納米片與多壁碳納米管進(jìn)行了復(fù)合,制備了不同碳納米管含量的SnO_2/MCNTs復(fù)合材料。研究結(jié)果表明:多壁碳納米管含量為50%的SnO_2/MCNTs復(fù)合材料的循環(huán)性能最佳,在160mA/g的電流密度下,經(jīng)過(guò)50次循環(huán)后,放電比容量維持在480.6mAh/g。3.在MCNTs50-SnO_2復(fù)合材料表面包覆PPy,制得了不同PPy含量的PPy-MCNTs/SnO_2復(fù)合材料。研究結(jié)果表明:聚吡咯含量為11%時(shí),PPy-MCNTs/SnO_2復(fù)合材料的循環(huán)性能最好,在160mA/g的電流密度下,循環(huán)100次后,可逆容量維持在525.8mAh/g。且相對(duì)于MCNTs/SnO_2復(fù)合材料,包覆PPy后的循環(huán)性能更好,更穩(wěn)定。
[Abstract]:In recent years, tin dioxide has been regarded as one of the most promising anode materials for lithium ion batteries. However, the volume expansion of tin dioxide in the first charge / discharge process is more than 50%. During the cycle, the repeated intercalation and deintercalation of lithium ions are prone to powder and agglomeration, so that the electrochemical performance of tin dioxide drops rapidly, which limits its wide application in lithium ion batteries. It has become the bottleneck of its application and popularization. How to effectively alleviate the volume effect and powdering phenomenon of tin dioxide in charge and discharge process and improve the cycle stability of the electrode has become the key to study the tin dioxide negative electrode material. The researchers have made great progress in overcoming the limitations of tin dioxide negative electrode materials in the following ways. One is the preparation of nanostructured tin dioxide, such as SnO_2 nanowires, SnO2 nanowires, SnO2 nanoarrays, and so on. By changing the morphology of the material and reducing the particle size of the material to increase the porosity of the material, the volume effect of the material during charge and discharge can be alleviated to a certain extent. For example, carbon coated SnO2- carbon nanotube composite Sno _ 2-graphene composite, by coating inorganic or organic substances on the surface of the material to limit the damage of the volume effect on the structure and properties of the material during charge and discharge. In this paper, the hydrothermal method is used to synthesize the SnO_2 material. The results show that SnO-2 nanocrystalline has the best electrochemical performance. On the basis of this, the modification of SnO_2 nanoparticles was carried out in the following three aspects. 1. The composite of SnO_2 nanoparticles and graphene oxide was carried out. SnO_2/ graphene nanocomposites with different graphene oxide contents were prepared. The results showed that the SnO_2/ graphene nanocomposites with 50% graphene oxide content had the best cycling performance. Under the current density of 160mA/g, after 100 cycles, The specific discharge capacity was maintained at 636.2mAh路 g.2.The composite of SnO_2 nanoparticles and multi-walled carbon nanotubes (MCNTs) was prepared, and the SnO_2/MCNTs composites with different carbon nanotubes contents were prepared. The results showed that the SnO_2/MCNTs composites with 50% MwCNT content had the best cycling performance. At the current density of 160mA/g, after 50 cycles, The specific discharge capacity was maintained at 480.6 mg 路路g. 3. The PPy-MCNTs/SnO_2 composites with different PPy content were prepared by coating PPy on the surface of MCNTs50-SnO_2 composites. The results showed that PPy-MCNTs / SnO2 composites had the best cycling performance when the PPY-MCNTs / SnO2 content was 11, and at the current density of 160mA/g, the composites had the best cycling performance. After 100 cycles, the reversible capacity is maintained at 525.8 mg 路h / g, and the cyclic performance of PPy coated with PPy is better and more stable than that of MCNTs/SnO_2 composite.
【學(xué)位授予單位】：天津工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TM912

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本文編號(hào)：1667552