【摘要】：鋰離子電池（LIBs）具有高功率密度、高能量密度等優(yōu)點(diǎn)，并且其在電動汽車、移動設(shè)備、醫(yī)療和手機(jī)等各個領(lǐng)域應(yīng)用廣泛。鋰離子電池（LIBs）的正極材料在其結(jié)構(gòu)中又占有舉足輕重的地位，而橄欖石狀的磷酸亞鐵鋰因?yàn)榫哂袃?yōu)良的電化學(xué)性能以及價格低廉、無毒、優(yōu)良的熱穩(wěn)定性、環(huán)境友好等優(yōu)點(diǎn)受到廣泛的關(guān)注，但是磷酸亞鐵鋰的應(yīng)用因低的離子電導(dǎo)率和低的導(dǎo)電性這些缺點(diǎn)而受到限制，通過提高磷酸亞鐵鋰的導(dǎo)電性和控制顆粒尺寸來提高鋰離子電池的電化學(xué)性能顯得尤為重要。 本論文主要從兩個方面對磷酸亞鐵鋰進(jìn)行了改性研究。利用X射線衍射儀（XRD），掃描電子顯微鏡（SEM）對材料晶體結(jié)構(gòu)、表觀形貌和化學(xué)成分進(jìn)行了分析表征，以觀察顆粒的尺寸與形貌，分析表面形貌對材料性能的影響，從而優(yōu)化材料的電化學(xué)性能；采用恒電流充放電測試技術(shù)對其電化學(xué)性能進(jìn)行測定分析，探索了最佳條件下的合成方法。 （1）采用傳統(tǒng)的固相法合成鋰離子電池正極材料LiFePO4/C，加入乙二醇進(jìn)行表面改性，并且研究了在不同的煅燒溫度（650℃，700℃，750℃）下，乙二醇對LiFePO4/C顆粒形貌的影響。在700℃下經(jīng)乙二醇改性的LiFePO4/C顆粒呈板狀堆積，在不同的電流密度下充放電平臺穩(wěn)定，并且具有較好的循環(huán)效率。 （2）利用水熱法和后期煅燒的方法合成鎳摻雜的LiFe1-xNixPO4/C （x=0.05，0.1，0.15）。Ni2+摻雜的樣品的顆粒尺寸為400-500nm，具有良好的結(jié)晶度和顆粒形貌，其中LiFe0.9Ni0.1PO4具有更好的晶體結(jié)構(gòu)和電化學(xué)性能，在0.1C倍率下的放電比容量達(dá)到150mAh·g1，，在0.1mV/s掃描速率下氧化還原峰的電勢差較小，具有更好的可逆性和更高的導(dǎo)電性。
[Abstract]:Li-ion battery (Libs) has many advantages such as high power density and high energy density, and it is widely used in many fields such as electric vehicles, mobile devices, medical treatment and mobile phones. Li-ion battery (Libs) cathode material plays an important role in its structure, and olivine like lithium ferrous phosphate has excellent electrochemical performance, low price, non-toxic, excellent thermal stability. Environmental friendliness has attracted wide attention, but the application of lithium ferrous phosphate is limited by the disadvantages of low ionic conductivity and low conductivity. It is very important to improve the electrochemical performance of lithium ion battery by improving the conductivity of lithium iron phosphate and controlling the particle size. In this paper, the modification of lithium ferrous phosphate was studied from two aspects. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze and characterize the crystal structure, apparent morphology and chemical composition of the materials, to observe the size and morphology of the particles, and to analyze the effect of surface morphology on the properties of the materials. In order to optimize the electrochemical performance of the material, the electrochemical performance of the material was measured and analyzed by using constant current charge-discharge test technology. The optimum conditions were investigated. (1) LiFePO _ 4 / C, a cathode material for lithium-ion battery, was synthesized by conventional solid-state method and modified with ethylene glycol, and the calcination temperature (650 鈩

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