本文選題：鋰離子電池　切入點(diǎn)：LiFePO_4/C　出處：《哈爾濱工業(yè)大學(xué)》2010年碩士論文　論文類型：學(xué)位論文

【摘要】：鋰離子電池正極材料磷酸亞鐵鋰以其具有無毒、充放電電壓平穩(wěn)、穩(wěn)定性好、循環(huán)性能好以及成本低等優(yōu)點(diǎn)受到廣泛關(guān)注。流變相法和溶膠凝膠法制備過程原料混合均勻,制備材料尺寸小,利于充放電循環(huán)。以三價(jià)鐵做鐵源制備磷酸亞鐵鋰成本低、過程簡(jiǎn)單,所以本研究考慮以三價(jià)鐵做鐵源,用流變相法和溶膠凝膠法制備了純相和金屬離子摻雜的LiFePO4/C復(fù)合材料,并測(cè)試其室溫下循環(huán)性能與倍率性能。通過X射線衍射(XRD)、掃描電鏡(SEM)等表征手段分析所制備的LiFePO4/C復(fù)合材料的結(jié)構(gòu)與形貌特點(diǎn),并由循環(huán)伏安、電化學(xué)交流阻抗等電化學(xué)測(cè)試手段測(cè)試材料的循環(huán)可逆性和阻抗性能。 利用溶膠凝膠法制備LiFePO4/C材料,考察了不同絡(luò)合劑、預(yù)燒溫度、鋰鹽和添加量、燒結(jié)溫度、燒結(jié)時(shí)間對(duì)材料性能的影響,得出以硝酸鐵：硝酸鋰：磷酸二氫銨：檸檬酸=1：1.05：1：1,60mass%的蔗糖為原料,在260℃下預(yù)燒2h,650℃下燒結(jié)6h,所制備的材料0.2C放電下容量能夠達(dá)到122mAh/g。 以硝酸鐵、磷酸二氫銨、氫氧化鋰、蔗糖做為原料、以流變相法制備前驅(qū)體,通過高溫?zé)Y(jié)制備了LiFePO4/C正極材料,并且研究了不同金屬離子的摻雜對(duì)材料性能的影響。結(jié)果表明,350℃預(yù)燒4h,650℃燒結(jié)18h制備的磷酸亞鐵鋰材料0.2C放電容量能夠達(dá)到123mAh/g,0.5C放電下容量能夠達(dá)到108mAh/g,1C放電下容量能夠達(dá)到97mAh/g。對(duì)材料進(jìn)行Zr4+、Al3+、Mg2+摻雜結(jié)果表明,摻雜Mg2+的材料性能最好,2%的Mg2+時(shí),0.2C放電下能夠達(dá)到140mAh/g,0.5C下放電容量為120mAh/g,1C放電容量為112mAh/g,且循環(huán)50次容量無衰減。 用硝酸鐵、磷酸二氫銨、硝酸鋰、蔗糖做為原料,利用流變相法制備前驅(qū)體,通過高溫?zé)Y(jié)制備LiFePO4/C正極材料,考察了溫度和時(shí)間對(duì)材料性能的影響。結(jié)果表明,260℃預(yù)燒2h,650℃燒結(jié)6h制備的磷酸亞鐵鋰材料,在0.2C充放電倍率下的質(zhì)量比容量可達(dá)140mAh/g,0.5C為133mAh/g,1C為130mAh/g;對(duì)材料進(jìn)行Mg2+摻雜研究表明,乙酸鎂按化學(xué)計(jì)量比2%摻雜,合成樣品在0.2C的放電容量保持在143mAh/g;在1C充電,1C、2C、5C、10C的放電倍率下放電容量保持在128mAh/g,109mAh/g,94mAh/g,84mAh/g,表現(xiàn)出良好的倍率性能,同時(shí)循環(huán)十次容量無衰減。
[Abstract]:Lithium Ferrous Phosphate, a cathode material for lithium ion batteries, has attracted wide attention due to its advantages of non-toxic, stable charge and discharge voltage, good cycling performance and low cost. The raw materials of the preparation process by rheological phase method and sol-gel method are uniformly mixed. The preparation of lithium ferrous phosphate with trivalent iron as Tie Yuan has a low cost and a simple process, so this study considered the use of trivalent iron as Tie Yuan. Pure phase and metal ion doped LiFePO4/C composites were prepared by rheological phase method and sol-gel method. The structure and morphology of the LiFePO4/C composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the structure and morphology of the composites were characterized by cyclic voltammetry. Electrochemical impedance and other electrochemical methods were used to test the cycle reversibility and impedance of the materials. LiFePO4/C materials were prepared by sol-gel method. The effects of different complexing agents, pre-sintering temperature, lithium salt and addition amount, sintering temperature and sintering time on the properties of the LiFePO4/C materials were investigated. The results show that the raw material of sucrose of 1: 1.05: 1: 1: 1mass60% ferric nitrate: lithium nitrate: ammonium dihydrogen phosphate: 1: 1.05: 1: 1: 1 is sintered at 260 鈩，

本文編號(hào)：1598809