本文選題：鋰離子電池 + 磷酸鐵鋰�。� 參考：《鄭州大學(xué)》2014年碩士論文

【摘要】：磷酸鐵鋰正極材料因具有鐵、磷原料豐富，價格低廉，比容量大，高溫性能優(yōu)異，高功率輸出，，循環(huán)壽命長，環(huán)境友好等優(yōu)勢成為電池行業(yè)的研究熱點。磷酸鐵鋰電池有潛力大規(guī)模應(yīng)用于純電動汽車、儲能裝置等領(lǐng)域。然而磷酸鐵鋰存在鋰離子擴散系數(shù)小、電子電導(dǎo)率低和振實密度低等缺點，削弱了它的大電流放電能力，阻礙了其工業(yè)化應(yīng)用。 本文采用微波法和溶劑熱兩種方法制備磷酸鐵鋰。首先是以碳酸鋰、磷酸鐵為原料，葡萄糖作還原劑和碳源，乙酸錳、二氧化鈦、氧化鎂分別為摻雜的錳源、鈦源和鎂源，采用微波法制備了摻雜單一或混合金屬陽離子的LiFePO4/C。研究了微波熱處理溫度和金屬離子摻雜對材料結(jié)構(gòu)和電化學(xué)性能的影響。其次，以乙二醇-水為體系，F(xiàn)eSO4·7H2O，H3PO4，LiOH·H2O為原料，抗壞血酸為還原劑，采用溶劑熱法制備了特定形貌的純相LiFePO4，研究了反應(yīng)物摩爾比、溶劑熱溫度、反應(yīng)時間、溶劑比例、表面活性劑對產(chǎn)物形貌和電化學(xué)性能的影響。主要結(jié)果如下： （1）微波熱處理溫度在650℃、700℃、750℃，保溫時間25min時均能合成純相的橄欖石結(jié)構(gòu)LiFePO4/C。其中650℃合成的樣品放電電壓最高，容量最大，性能最好。 （2）無論單一還是混合摻雜金屬離子（摻雜量≤1.5%）均不會改變LiFePO4的晶體結(jié)構(gòu)。相比碳包覆的LiFePO4，單一或混合摻雜Ti4+、Mn2+、Mg2+后提高了LiFePO4的大電流放電性能和電化學(xué)反應(yīng)的可逆性，且循環(huán)性能良好。其中摻雜錳、鈦離子分別為0.5%、1%時電化學(xué)性能最佳，0.2C倍率放電比容量138mAh/g；0.5C倍率放電比容量116mAh/g；1C倍率放電比容量105mAh/g；1C倍率循環(huán)20次后容量保持率在96.5%。 （3）溶劑乙二醇/水為1：1，加入陽離子表面活性劑CTAB均有利于沿（010）面方向生長。且加入陽離子表面活性劑CTAB后，磷酸鐵鋰的粒徑更小，分布更均勻，電化學(xué)性能有所提高。 （4）當(dāng)摩爾比Li+：Fe2+：PO43-=2.5：1：1，乙二醇/水=1：1，180℃反應(yīng)9h時合成紡錘體形狀的磷酸鐵鋰，表面是沿（010）面呈片狀生長。將LiFePO4與12wt%的葡萄糖進行碳包覆后，其0.1C倍率放電比容量為100.1mAh/g。
[Abstract]:Lithium iron phosphate cathode material has become a research hotspot in battery industry because of its advantages such as abundant iron, phosphorus, low cost, large specific capacity, excellent high temperature performance, high power output, long cycle life and environmental friendliness.Lithium iron phosphate batteries have the potential to be widely used in pure electric vehicles, energy storage devices and other fields.However, lithium iron phosphate has the disadvantages of low lithium ion diffusion coefficient, low electronic conductivity and low vibrational density, which weakens its high current discharge ability and hinders its industrial application.Lithium iron phosphate was prepared by microwave method and solvothermal method.Firstly, lithium carbonate and iron phosphate were used as raw materials, glucose as reducing agent and carbon source, manganese acetate, titanium dioxide and magnesium oxide as doped manganese source, titanium source and magnesium source respectively. LiFePO _ 4 / C doped with single or mixed metal cations was prepared by microwave method.The effects of microwave heat treatment temperature and metal ion doping on the structure and electrochemical properties of the materials were studied.Secondly, pure phase LiFePO _ 4 with specific morphology was prepared by solvothermal method with FeSO _ 4 _ 7H _ 2O H _ 3PO _ 4H _ 2O as raw material and ascorbic acid as reducing agent. The molar ratio of reactants, solvothermal temperature, reaction time and solvent ratio were studied.Effects of surfactants on the morphology and electrochemical properties of the products.The main results are as follows:1) the pure olivine structure LiFePO _ 4 / C can be synthesized by microwave heat treatment at 650 鈩

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