本文關(guān)鍵詞： 鈉離子電池 負(fù)極材料 溶膠凝膠 石墨烯納米片 硫化鈷 電化學(xué)性能　出處：《南京理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鋰離子電池由于高電壓、高能量密度,以及循環(huán)穩(wěn)定性等特點(diǎn),被認(rèn)為是優(yōu)異的儲(chǔ)能系統(tǒng)。然而,鋰資源在地殼中的儲(chǔ)量十分有限,這成為制約大規(guī)模儲(chǔ)能系統(tǒng)發(fā)展的瓶頸。而鈉資源儲(chǔ)量豐富、成本低廉,又具有與鋰元素相似的物理、化學(xué)特性及儲(chǔ)能機(jī)制,被視為有望替代鋰離子電池的下一代電池。但是,由于鈉的相對(duì)原子質(zhì)量和離子半徑較大,使鈉離子在材料中嵌入脫出更難。因此,研究高性能的儲(chǔ)鈉電極材料具有重要意義。本論文旨在制備高性能的鈉離子電池負(fù)極材料,改善材料的容量、循環(huán)性能、倍率性能,使其具有一定的應(yīng)用價(jià)值。主要研究?jī)?nèi)容包括以下幾個(gè)方面:一,采用溶膠凝膠法制備摻氮功能石墨烯納米片,通過(guò)改變燒結(jié)溫度,獲得合適氮含量且形貌優(yōu)異的石墨烯納米片(750℃),該方法大大簡(jiǎn)化了石墨烯的制備過(guò)程。750℃下的樣品在0.1Ag~(-1)下能夠提供225mAhg~(-1)的可逆容量;在1Ag~(-1)下循環(huán)2000周,還有約150mAhg~(-1)的可逆容量;不足之處在于比容量較低,由于二維材料易于團(tuán)聚堆疊的特性,限制了比表面積的發(fā)揮,使石墨烯在儲(chǔ)能過(guò)程中性能遠(yuǎn)不及理論計(jì)算。二,(1)為了抑制石墨烯納米片的堆疊,提高摻氮功能石墨烯納米片的容量,通過(guò)改進(jìn)的溶膠凝膠法,使硫化鈷顆粒(Co_(1-x)S)原位生長(zhǎng)在功能石墨烯納米片(FGNs)上,獲得Co_(1-x)S/FGNs納米復(fù)合材料。容量遠(yuǎn)大于摻氮功能石墨烯納米片(466mAhg~(-1)在1001mAg~(-1),211mAhg~(-1)在10Ag~(-1));并且具有較好的循環(huán)穩(wěn)定性,在1Ag~(-1)下循環(huán)200周后,還保留了 251mAhg~(-1)的容量。(2)通過(guò)對(duì)比Co_(1-x)S/FGNs與Co_(1-x)S和FGNs在電化學(xué)性能上的差異,以突出Co_(1-x)S/FGNs在結(jié)構(gòu)設(shè)計(jì)上的優(yōu)勢(shì)。如FGNs在0.1Ag~(-1)下只有275mAhg~(-1)的比容量,Co_(1-x)S在1Ag~(-1)下循環(huán)130周后,容量已降至約50mAhg~(-1)。因此,Co_(1-x)S/FGNs的優(yōu)勢(shì)可以歸因于FGNs的納米薄片和Co_(1-x)S的小顆粒縮小了鈉離子的擴(kuò)散距離;FGNs的摻雜元素(氮、硫)提供更多的儲(chǔ)鈉位點(diǎn);原位的復(fù)合方法有效提高材料的穩(wěn)定性,進(jìn)而提高了電極的倍率性能和循環(huán)性能。
[Abstract]:Lithium ion batteries are considered to be excellent energy storage systems due to their high voltage, high energy density and cycle stability. However, the reserves of lithium in the earth's crust are very limited. This has become a bottleneck restricting the development of large-scale energy storage systems. Sodium is abundant in reserves, low in cost, and has physical, chemical and energy storage mechanisms similar to that of lithium, which is considered to be the next generation battery to replace lithium ion batteries. Because the relative atomic mass and ionic radius of sodium are larger, it is more difficult to intercalate sodium ions into the materials. Therefore, it is of great significance to study the high performance sodium storage electrode materials. In this paper, the purpose of this paper is to prepare high performance negative electrode materials for sodium ion batteries. The main research contents are as follows: firstly, nitrogen-doped graphene nanocrystals were prepared by sol-gel method, and the sintering temperature was changed. The method greatly simplifies the preparation process of graphene. The method can provide the reversible capacity of 225mAhgcn-1) at 0.1AgGG ~ (-1), and the reversible capacity of about 150mAhg-1) for 2000 weeks under the cyclic condition of 1AgGG ~ (-1), and the reversion capacity of graphene nanocrystalline is about 150mAhg-1) by using the method of preparing graphene nanocrystalline at 750 鈩，

本文編號(hào)：1525069