本文選題：螺旋納米碳纖維　切入點：化學(xué)氣相沉積法　出處：《四川理工學(xué)院》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：鋰離子電池具有開路電壓高,比容量大,安全環(huán)保,使用壽命長等諸多優(yōu)點,已在各領(lǐng)域廣泛使用,但動力型和大功率設(shè)備的大量應(yīng)用對鋰離子電池提出了更高要求,傳統(tǒng)的碳材料已不能滿足高性能的鋰離子電池要求,只有探索新的儲能材料才能突破鋰離子電池的發(fā)展瓶頸。螺旋納米碳纖維的導(dǎo)電性能好,比表面積大,石墨片層結(jié)構(gòu)無序度高,能提供更多鋰離子嵌入與脫出的通道,有利于提高鋰離子電池的充放電容量、循環(huán)穩(wěn)定性以及倍率性能。本文主要研究螺旋納米碳纖維的制備、微觀結(jié)構(gòu)與電化學(xué)性能。(1)以三水合酒石酸銅為催化劑前驅(qū)體、乙炔為碳源,采用化學(xué)氣相沉積法制備螺旋納米碳纖維。在250-380℃制備的螺旋納米碳纖維,螺旋不規(guī)則,直徑在100-300nm;在480-680℃制備的螺旋納米碳纖維,螺旋規(guī)則,形貌均勻,直徑約為100nm左右。在480℃的低溫條件下制備出螺旋規(guī)則、形貌均勻的螺旋納米碳纖維,實驗流程簡單,操作方便,實驗重現(xiàn)性好,能耗和成本低,可推廣到工業(yè)化。(2)480℃、580℃、680℃制備的螺旋納米碳纖維作為鋰電池負(fù)極材料,首次放電比容量分別為811m Ah/g、702m Ah/g、613m Ah/g,循環(huán)充放電40次后,放電比容量分別為503m Ah/g、443m Ah/g、439m Ah/g,庫倫效率分別為97.8%、98.6%、97%,表現(xiàn)出良好的循環(huán)性能和高倍率性能。在一定溫度范圍,隨著制備溫度的升高,螺旋納米碳纖維的石墨片層有序度提高,可逆嵌鋰容量降低。(3)DNA狀、彈簧狀、麻花狀的螺旋納米碳纖維作為鋰電池負(fù)極材料,首次放電比容量分別是1066m Ah/g、834m Ah/g、702m Ah/g,循環(huán)充放電40次后,放電比容量分別為584m Ah/g、501m Ah/g、443m Ah/g,庫倫效率分別為98.5%、99%、98.6%。DNA狀的螺旋納米碳纖維的充放電比容量最高,彈簧狀的次之,麻花狀的最低。DNA狀的螺旋納米碳纖維表面粗糙,碳沉積不規(guī)則,為維持其DNA結(jié)構(gòu)的螺旋,出現(xiàn)許多“搭接孔”或“微裂紋”,鋰離子可嵌入到碳納米纖維的石墨微晶的表面及邊緣,為鋰離子的脫出和嵌入提供更多的通道,更利于充放電。
[Abstract]:Li-ion batteries have many advantages such as high open-circuit voltage, large specific capacity, safety and environmental protection, long service life and so on, and have been widely used in various fields. However, a large number of applications of power and high-power equipment put forward higher requirements for lithium-ion batteries. Traditional carbon materials can not meet the requirements of high performance lithium ion batteries. Only by exploring new energy storage materials can we break through the development bottleneck of lithium ion batteries. The graphite lamellar structure has a high degree of disorder and can provide more channels for intercalation and removal of lithium ions, which is beneficial to the improvement of the charge and discharge capacity, cyclic stability and performance of the lithium ion battery. In this paper, the preparation of spiral carbon nanofibers is studied. Using copper tartrate trihydrate as catalyst precursor and acetylene as carbon source, spiral carbon nanofibers were prepared by chemical vapor deposition. The spiral carbon nanofibers prepared at 480-680 鈩，

本文編號：1641624