發(fā)布時(shí)間：2018-02-01 10:29

  本文關(guān)鍵詞： 鋰離子電池 碳納米纖維 CoO/CNF FeCO_3/CNF Fe_2O_3/CNF　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鋰離子電池憑借其能量密度較高、循環(huán)性能優(yōu)良、使用壽命較長、安全環(huán)保、無記憶效應(yīng)等特點(diǎn),成為新能源材料的研究熱點(diǎn),目前已被廣泛應(yīng)用于智能手機(jī)、筆記本電腦等電子產(chǎn)品行業(yè)以及動力汽車、混合動力汽車行業(yè)。然而,隨著人們對鋰離子電池需求量的日益增加,開發(fā)出能量密度更高、循環(huán)性能更好、使用壽命更長的新型鋰離子電池已經(jīng)成為新能源領(lǐng)域最具有價(jià)值的研究之一。負(fù)極材料作為鋰離子電池的核心材料之一,是決定鋰離子電池儲鋰性能的關(guān)鍵材料。目前商業(yè)上通常采用循環(huán)穩(wěn)定性優(yōu)良的碳材料作為負(fù)極材料,但是,碳材料理論容量較低,僅372 mAh g~(-1),其較低的儲鋰性能并不能滿足人類對鋰離子電池日益增長的需求。近十年,過渡金屬化合物由于其較高的理論容量受到國內(nèi)外研究人員的廣泛關(guān)注,然而,這類材料受SEI膜和體積效應(yīng)限制,循環(huán)穩(wěn)定性能較差,同樣無法滿足人類的需求。本文綜合考慮碳材料及過渡金屬化合物材料的優(yōu)缺點(diǎn),結(jié)合前人經(jīng)驗(yàn),首次提出將碳納米纖維與過渡金屬化合物復(fù)合,采用不同方法制備出過渡金屬化合物/碳納米纖維柔性膜,打破傳統(tǒng)拌漿工藝,簡化電池組裝流程,實(shí)現(xiàn)了負(fù)極材料可逆容量與循環(huán)穩(wěn)定性能的雙重突破。本論文具體內(nèi)容如下:(1)通過靜電紡絲技術(shù)制備碳納米纖維(CNF),結(jié)果表明:該方法合成的CNF表面光滑,呈現(xiàn)網(wǎng)狀結(jié)構(gòu),循環(huán)穩(wěn)定性能優(yōu)異,可逆容量偏低,在200mA g~(-1)的電流密度下循環(huán)150圈以后,材料比容量為285.6 mAh g~(-1)。(2)以CNF為基底、硝酸鈷為金屬源、尿素為配體、去離子水和乙醇為溶劑,采用冷凝回流法合成了CoO/CNF復(fù)合材料,結(jié)果表明:在CoO/CNF復(fù)合材料中,CoO納米片團(tuán)聚成柳絮狀CoO微米球鑲嵌在CNF纖維中,表現(xiàn)出優(yōu)秀的電化學(xué)性能,在200 mA g~(-1)的電流密度下循環(huán)150圈以后,材料比容量為579.7mAh g~(-1),其中,CoO為整個(gè)材料提供的比容量高達(dá)774.1 mAh g~(-1)。(3)以CNF為基底、氯化鐵為金屬源、尿素為配體、抗壞血酸為還原劑、去離子水為溶劑,采用傳統(tǒng)水熱法合成了FeCO_3/CNF復(fù)合材料,結(jié)果表明:該方法合成的FeCO_3/CNF復(fù)合材料呈現(xiàn)蜂窩狀結(jié)構(gòu),表現(xiàn)出優(yōu)秀的電化學(xué)性能,在200 mA g~(-1)的電流密度下循環(huán)200圈以后,材料比容量為546.2 mAh g~(-1),其中,FeCO_3為整個(gè)材料提供的比容量高達(dá)919.7 mAh g~(-1)。(4)以CNF為基底、氯化鐵為金屬源、尿素為配體、乙醇為溶劑,采用微波水熱法合成了Fe_2O_3/CNF復(fù)合材料,結(jié)果表明:該方法合成的Fe_2O_3/CNF復(fù)合材料呈現(xiàn)蜂窩狀結(jié)構(gòu),表現(xiàn)出優(yōu)秀的電化學(xué)性能,在200 mA g~(-1)的電流密度下循環(huán)150圈以后,材料比容量為673.8 mAh g~(-1),其中,Fe_2O_3為整個(gè)材料提供的比容量高達(dá)926.2 mAh g~(-1)。
[Abstract]:Li-ion battery has become the research focus of new energy materials because of its high energy density, good cycling performance, long service life, safety and environmental protection, no memory effect and so on, and has been widely used in smart phones. However, with the increasing demand for lithium ion batteries, higher energy density and better cycle performance have been developed. New lithium-ion batteries with longer service life have become one of the most valuable research fields in the field of new energy. Negative electrode materials as one of the core materials of lithium-ion batteries. Carbon materials with good cyclic stability are usually used as negative electrode materials, but the theoretical capacity of carbon materials is relatively low. Its low lithium storage performance can not meet the increasing demand for lithium-ion batteries in recent ten years. Transition metal compounds have attracted much attention because of their high theoretical capacity. However, due to the limitation of SEI film and volume effect, the cyclic stability of transition metal compounds is poor. In this paper, we consider the advantages and disadvantages of carbon materials and transition metal compounds, combined with previous experience, the first time to put forward the carbon nanofibers and transition metal compounds composite. Transition metal compounds / carbon nanofiber flexible films were prepared by different methods to break the traditional slurry mixing process and simplify the battery assembly process. The reversible capacity and cyclic stability of negative electrode materials have been achieved. The main contents of this thesis are as follows: (1) carbon nanofibers CNF were prepared by electrospinning technology. The results show that the CNF synthesized by this method has a smooth surface, a reticular structure, excellent cyclic stability and low reversible capacity, after the current density of 200mA / g ~ (-1). The specific capacity of the material is 285.6 mAh / g ~ (-1) / L ~ (-1)) based on CNF, cobalt nitrate as metal source, urea as ligand, deionized water and ethanol as solvent. CoO/CNF composites were synthesized by condensation reflux method. The results showed that the CoO/CNF composites were agglomerated to form cataclysmic CoO microspheres embedded in CNF fibers. It showed excellent electrochemical performance, and the specific capacity of the material was 579.7 mAh / g ~ (-1) after 150 cycles under the current density of 200 Ma / g ~ (-1), in which the specific capacity of the material was 579.7 mAh / g ~ (-1). The specific capacity of CoO for the whole material was as high as 774.1 mAh / g ~ (-1) / L ~ (3)) based on CNF, ferric chloride as metal source, urea as ligand, ascorbic acid as reducing agent. FeCO_3/CNF composites were synthesized by conventional hydrothermal method using deionized water as solvent. The results show that the FeCO_3/CNF composites synthesized by this method have honeycomb structure. It shows excellent electrochemical performance, and the specific capacity of the material is 546.2 mAh / g ~ (-1) after cycling at a current density of 200mA / g ~ (-1), in which the specific capacity of the material is 546.2 mAh / g ~ (-1). The specific capacity of FeCO_3 for the whole material is as high as 919.7 mAh / g ~ (-1) / L ~ (4). CNF is used as the substrate, ferric chloride as metal source, urea as ligand and ethanol as solvent. Fe_2O_3/CNF composites were synthesized by microwave hydrothermal method. The results show that the Fe_2O_3/CNF composites prepared by this method have honeycomb structure. It shows excellent electrochemical performance, and the specific capacity of the material is 673.8 mAh / g ~ (-1) after the current density of 200mA / g ~ (-1) is circulated in 150th cycle, in which the specific capacity of the material is 673.8 mAh / g ~ (-1). The specific capacity of Fe_2O_3 for the whole material is up to 926.2 mAh / g ~ (-1).
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB332;TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前6條

1 ;Micro-sized and Nano-sized Fe_3O_4 Particles as Anode Materials for Lithium-ion Batteries[J];Journal of Materials Science & Technology;2011年01期

2 王兆翔;陳立泉;;鋰離子電池正極材料研究進(jìn)展[J];電源技術(shù);2008年05期

3 黃彥瑜;;鋰電池發(fā)展簡史[J];物理;2007年08期

4 余碧濤,李福q，

本文編號：1481642