本文關(guān)鍵詞：高振實(shí)密度多孔鈦酸鋰微球的合成工藝及其性能研究　出處：《蘇州大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 鋰離子電池 鈦酸鋰 噴霧干燥 振實(shí)密度 多孔結(jié)構(gòu)

【摘要】：鈦酸鋰作為鋰離子電池負(fù)極材料,具有“零應(yīng)變”、安全性高等優(yōu)點(diǎn),受到了人們?cè)絹碓蕉嗟年P(guān)注。然而鈦酸鋰的電導(dǎo)率和振實(shí)密度很低,限制了它的大規(guī)模應(yīng)用。在提高鈦酸鋰的電導(dǎo)率方面已有大量研究,主要采用納米化、表面包覆和金屬元素?fù)诫s等方法。但在提高鈦酸鋰的振實(shí)密度方面的研究卻很少。本文采用噴霧干燥技術(shù),以碳酸鋰和銳鈦礦型二氧化鈦為原料通過二次煅燒法制備了振實(shí)密度高、循環(huán)性能好的多孔鈦酸鋰微球負(fù)極材料。二次煅燒法的目的是在噴霧干燥前先將原料混合煅燒,除去反應(yīng)生成的氣體形成前驅(qū)體產(chǎn)物,噴霧干燥后形成由一次顆粒組成的松散球形前驅(qū)體,經(jīng)再次煅燒,球形前驅(qū)體在高溫下收縮、熔融生長成既彼此相連又有介孔阻隔的球形鈦酸鋰材料。由此法制備的鈦酸鋰負(fù)極材料振實(shí)密度可達(dá)1.20 g cm-3,比一次煅燒法制備的鈦酸鋰振實(shí)密度(0.89 g cm-3)高出近1.4倍。而且,用此法制備的鈦酸鋰材料,因球形粒子內(nèi)有介孔存在而非常有利于電解液滲透,又因組成球形顆粒的一次粒子彼此相連而減少了接觸電阻,所以由此鈦酸鋰負(fù)極材料制備的鋰離子電池具有非常優(yōu)異的循環(huán)性能。在1 C下充放電,循環(huán)400圈后的容量保持率仍為98.35%。我們還對(duì)噴霧干燥條件、煅燒溫度、時(shí)間進(jìn)行了系統(tǒng)研究。發(fā)現(xiàn)在料液濃度為0.28 g mL-1時(shí),第二次煅燒在850℃下進(jìn)行8 h得到的高振實(shí)密度多孔鈦酸鋰微球(LTO-850),其綜合性能最優(yōu)。此外,還對(duì)LTO-850微球進(jìn)行改性研究,包括:通過調(diào)整原料的Li:Ti摩爾比獲得TiO2-Li4Ti5O12微球;LTO-850微球電極不添加導(dǎo)電劑;球形前驅(qū)體在不同氣氛下(空氣,H2-Ar混合氣)經(jīng)過煅燒得到樣品;鈦酸鋰的高低溫性能等內(nèi)容。
[Abstract]:Lithium titanate, as a cathode material for lithium ion batteries, has attracted more and more attention due to its advantages of "zero strain" and high safety. However, the conductivity and vibrational density of lithium titanate are very low. A lot of research has been done to improve the conductivity of lithium titanate, which is mainly nanocrystalline. The methods of surface coating and metal element doping are few in improving the vibrational density of lithium titanate. Spray drying technique is used in this paper. Lithium carbonate and anatase titanium dioxide were used as raw materials to prepare high vibrational density by secondary calcination. The aim of the secondary calcination method is to mix the raw materials before spray drying and to remove the gases generated by the reaction to form precursor products. After spray drying, a loose spherical precursor composed of primary particles was formed. After re-calcination, the spherical precursor shrank at high temperature. A spherical lithium titanate material with interlinked mesoporous barrier was prepared by melt growth. The vibrational density of lithium titanate anode prepared by this method can reach 1.20 g cm-3. The vibrational density of lithium titanate prepared by the single calcination method is nearly 1.4 times higher than that of the lithium titanate prepared by this method. Because of the existence of mesoporous particles in the spherical particles, the electrolyte permeation is very favorable, and the contact resistance is reduced because the primary particles that make up the spherical particles are connected with each other. Therefore, the lithium ion battery prepared from the lithium titanate anode material has excellent cycling performance. It is charged and discharged at 1C. The capacity retention rate was 98.35 after 400 cycles. We also studied the spray drying conditions, calcination temperature and time. It was found that the concentration of the liquid was 0.28 g mL-1. The high density porous lithium titanate microspheres (LTO-850) obtained by the second calcination at 850 鈩，

本文編號(hào)：1413755