本文選題：二氧化錳　切入點(diǎn)：二氧化鈦　出處：《南京大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來(lái),隨著石油、天然氣等傳統(tǒng)化石能源日漸枯竭,太陽(yáng)能、風(fēng)能等新能源受到越來(lái)越多的關(guān)注。這些替代能源的高效利用仰賴于高性能化學(xué)電源的發(fā)展。而鋰離子電池是目前研究和應(yīng)用最廣泛的化學(xué)電源之一。與其它化學(xué)電源相比而言,鋰離子電池具有能量密度高、使用壽命長(zhǎng)、循環(huán)性能好、安全性能好等優(yōu)點(diǎn),現(xiàn)已經(jīng)廣泛應(yīng)用于筆記本電腦、數(shù)碼相機(jī)、移動(dòng)電話等移動(dòng)設(shè)備中。然而目前鋰離子電池的電化學(xué)性能還不能滿足純電動(dòng)汽車(EVs)或混合動(dòng)力汽車(HEVs)等大功率設(shè)備的需求。作為鋰離子電池三大基本要素(正極、負(fù)極、電解質(zhì))之一的負(fù)極材料一直是鋰離子電池研究的關(guān)鍵課題。錳的氧化物由于具有較高的比容量,很早就將其作為儲(chǔ)鋰負(fù)極材料進(jìn)行研究。然而,由于其電子傳導(dǎo)率和鋰離子擴(kuò)散速率較低,且充放電過(guò)程中體積易發(fā)生不可逆的變化,導(dǎo)致材料的粉化,使得容量衰減較快,循環(huán)能力和快速充放電能力差,因此制約了錳氧化物在鋰離子電池負(fù)極材料領(lǐng)域中的應(yīng)用。本論文的研究?jī)?nèi)容是針對(duì)錳氧化物的上述不足,利用二氧化鈦修飾及摻氮等手段對(duì)錳氧化物進(jìn)行改性,以提高材料的導(dǎo)電性和鋰離子在材料中的擴(kuò)散速率,減緩材料因體積變化造成的粉化現(xiàn)象,達(dá)到提升電化學(xué)性能的目的。1.通過(guò)水熱方法制備MnCO_3自組裝微球,在空氣氣氛中400 ℃焙燒4 h后氧化為MnO_2,然后加入鈦酸四丁酯水解,通過(guò)后期再燒結(jié)過(guò)程后生成TiO2/MnOx復(fù)合材料。與二氧化錳相比,復(fù)合材料容量衰減較慢,循環(huán)能力大幅提升,在100 mA/g下經(jīng)過(guò)250次循環(huán)后比容量保持在1032 mAh/g。性能的提高可能源于二氧化鈦結(jié)構(gòu)的穩(wěn)定性部分緩解了錳氧化物的體積膨脹,Mn~(3+)的存在使得導(dǎo)電性提高,以及二氧化鈦和氧化錳間的協(xié)同作用。7Li核磁共振的結(jié)果證明了復(fù)合物中二氧化鈦儲(chǔ)鋰的嵌入機(jī)理及錳氧化物儲(chǔ)鋰的轉(zhuǎn)化機(jī)理。2.通過(guò)硝酸錳和乙醇的水熱反應(yīng)在三聚氰胺泡棉上生成三氧化二錳顆粒,管式爐下燒結(jié)后泡棉分解為碳氮網(wǎng)絡(luò)結(jié)構(gòu),三氧化二錳還原為低價(jià)態(tài)的一氧化錳。由于碳氮網(wǎng)絡(luò)結(jié)構(gòu)的存在,提高了充放電過(guò)程中材料結(jié)構(gòu)的穩(wěn)定性及電子的傳輸效率,燒結(jié)后產(chǎn)生了電荷傳輸?shù)目椎澜Y(jié)構(gòu),材料的比容量和循環(huán)穩(wěn)定性大大提高。經(jīng)500℃處理后的MnO-MF-500材料在160次循環(huán)后仍然保留590 mAh/g的比容量,達(dá)到一氧化錳理論容量755 mAh/g的78%。
[Abstract]:In recent years, with oil, natural gas and other traditional fossil energy increasingly depleted, solar energy, New energy sources, such as wind energy, have attracted more and more attention. The efficient use of these alternative sources depends on the development of high performance chemical power sources. Lithium ion batteries are one of the most widely studied and widely used chemical power sources. In comparison with power supply, Li-ion batteries have the advantages of high energy density, long service life, good cycle performance, good safety performance, and have been widely used in notebook computers, digital cameras, etc. However, the electrochemical performance of lithium-ion battery can not meet the demand of high-power equipment such as pure electric vehicle (EVs) or hybrid electric vehicle (HEVs) at present. As the three basic elements of lithium-ion battery (positive electrode, negative electrode, and so on), the electrochemical performance of lithium-ion battery can not meet the demand of high-power equipment such as pure electric vehicle or hybrid electric vehicle. Because of its high specific capacity, manganese oxide has been used as a cathode material for lithium storage in a long time. However, because of its high specific capacity, manganese oxide has been used as a cathode material for lithium-ion batteries. Due to the low electron conductivity and lithium ion diffusion rate, and the irreversible change of the volume during charge and discharge, the material becomes powdered, which makes the capacity decay faster, and the cycling ability and rapid charge and discharge ability are poor. Therefore, the application of manganese oxide in the field of anode materials for lithium ion batteries is restricted. In order to improve the conductivity of the material and the diffusion rate of lithium ion in the material, to reduce the powder phenomenon caused by the volume change of the material and to improve the electrochemical performance. 1. The MnCO_3 self-assembled microspheres were prepared by hydrothermal method. After calcined at 400 鈩，

本文編號(hào)：1576671