本文選題：鋰離子電池 + ZnS��； 參考：《浙江大學(xué)》2017年碩士論文

【摘要】：社會發(fā)展到今天,人們對能源的依賴程度越來越深,提供能源的儲能設(shè)備越來越受到人們的重視。其中鋰離子二次電池受到全世界的廣泛關(guān)注。傳統(tǒng)的鋰離子電池已經(jīng)無法滿足人們要求,提高儲能設(shè)備的性能,是社會亟待解決的問題。負(fù)極是電池重要的組成部分,目前市場上常用的石墨負(fù)極,基本已經(jīng)接近理論比容量,已達(dá)到材料的上限。合金類、金屬氧化物、金屬硫化物具有高比容量、低成本、環(huán)境友好和安全性高等優(yōu)點,一直被認(rèn)為是極具潛力的下一代負(fù)極材料。然而,該類負(fù)極材料在充電過程中體積變化巨大、及氧化物硫化物導(dǎo)電性能差的問題,導(dǎo)致活性物質(zhì)粉化脫離主體,有效成分得不到有效利用,造成循環(huán)壽命差,阻礙進(jìn)一步實用化。我們以金屬ZnS為研究對象,對于其體積變化大和導(dǎo)電性差的問題,從以下方面對材料進(jìn)行改進(jìn);在材料中引入高導(dǎo)電性碳材料石墨烯(rGO),氧化石墨烯水溶液中引入鋅鹽離子,具有高的比表面積,且表面有各種含氧基團(tuán),能夠結(jié)合鋅鹽正離子。經(jīng)過高溫水熱反應(yīng),我們得到了具有特殊結(jié)構(gòu)復(fù)合材料,即石墨烯表面負(fù)載半球形空心納米ZnS顆粒的ZnS/rGO復(fù)合材料。通過控制溫度、原料配比得到不同形貌的復(fù)合材料,當(dāng)ZnS與GO比例達(dá)到1:1,反應(yīng)溫度為180℃時,得到空心ZnS顆粒粒徑為200 nm左右,在電流密度為100 mAg-1時,30次循環(huán)比容量仍有510 mAhg-1。通過增加還原劑葡萄糖尿素聚合樹脂的量和600℃高溫處理的手段,我們將石墨烯表面ZnS顆粒尺寸降到幾個納米大小,并在石墨烯表面成功覆蓋一層碳層。100次循環(huán)后比容量仍有714 mAhg-1。引入Fe元素,水熱過程直接加入Fe2+鹽,通過一步反應(yīng)得到摻雜Fe的ZnS/rGO-Fe復(fù)合材料,由SEM分析看出,材料仍然保持原來的半球空心形貌,XRD圖譜分析,鐵元素以FeS的形式存在。在電流密度為100mAhg-1,循環(huán)性能表現(xiàn)較好,100次循環(huán)后,剩余可逆比容量接近600 mAhg-1。我們將材料利用高溫熔融的方法,進(jìn)行載硫處理,在ZnS/rGO表面均勻覆蓋一層單質(zhì)硫,通過對不同原料配比的復(fù)合物進(jìn)行載硫和鋰硫電池電化學(xué)性能測試,探討ZnS的量對鋰硫電池電化學(xué)行為的影響。研究發(fā)現(xiàn)當(dāng)原料配比為10:1時,電池性能最好,100次循環(huán)后,可逆比容量仍有921 mAhg-1,容量保持率為90.5%。
[Abstract]:Nowadays, people depend more and more on energy, and more and more attention is paid to energy storage equipment. Among them, lithium ion secondary battery has been paid more and more attention all over the world. Traditional lithium ion batteries can not meet the needs of people. It is an urgent problem to improve the performance of energy storage equipment. Negative electrode is an important part of battery. Graphite anode, which is commonly used in the market at present, is close to the theoretical specific capacity and has reached the upper limit of material. Alloys, metal oxides and metal sulfides have been considered as the next generation of anode materials with high specific capacity, low cost, environmental friendliness and high safety. However, the large volume change in the charging process and the poor conductivity of oxide sulfides lead to the pulverization of active substances from the main body, and the lack of effective utilization of the active components, resulting in poor cycle life. Hinders further application. Taking metal ZnS as the research object, we improve the material from the following aspects: the introduction of high conductivity carbon material graphene rgol, the introduction of zinc salt ion in graphene oxide aqueous solution, the high conductivity carbon material, the high conductivity carbon material, the high conductivity carbon material, the high conductivity carbon material, the high conductivity carbon material, the zinc salt ion in the aqueous solution of graphene oxide. It has high specific surface area and various oxygen groups on the surface, which can bind zinc salt positive ions. By hydrothermal reaction at high temperature, we have obtained the ZnS/rGO composite with special structure, that is, the graphene surface loaded with hemispherical hollow ZnS particles. When the ratio of ZnS to go is 1: 1 and the reaction temperature is 180 鈩，

本文編號：1775631