溶膠凝膠法制備磷酸鐵鋰復(fù)合材料及其微結(jié)構(gòu)與磁性能研究
發(fā)布時間：2018-07-17 05:53
【摘要】：鋰離子電池正極材料橄欖石型磷酸鐵鋰具有對環(huán)境無污染、價格低、原料來源豐富、比能量高和安全性能突出等特點(diǎn),是最有潛力的鋰離子電池正極材料中的一種。但是鋰離子電池正極材料橄欖石型LiFePO4存在缺點(diǎn),第一是它的堆積密度小,這樣使得其體積比容量低,對應(yīng)做出來的電池體積相對較大。第二是其離子擴(kuò)散系數(shù)小及電導(dǎo)率低。而材料的電導(dǎo)率κ、磁性和空穴型極化子有關(guān)。橄欖石型磷酸鐵鋰中空穴的自旋與三價鐵陽離子(Fe3+)的(tg↑)3(eg↑)2電子結(jié)構(gòu)相關(guān),與擁有(tgT)3(egT)2tg↓電子結(jié)構(gòu)的二價鐵陽離子(Fe2+)通過雙交換機(jī)制發(fā)生鐵磁耦合,所以失去電子就會引起極子型的畸變,這時會產(chǎn)生自旋極化電荷云。本文使用操作簡單、合成條件易于控制、制備材料顆粒小等特點(diǎn)的溶膠凝膠法(sol-gel),通過一步法制備磷酸鐵鋰碳復(fù)合材料;通過兩步法制備金屬單質(zhì)銅與磷酸鐵鋰碳復(fù)合材料;通過兩步合成AxOy型金屬氧化物(二氧化錳、三氧化二鋁)與橄欖石型磷酸鐵鋰碳復(fù)合材料。并用TG、XRD、FTIR、SEM、VSM等方法對復(fù)合材料的合成過程樣品熱特性、物相結(jié)構(gòu)、官能團(tuán)及化學(xué)鍵、微觀表面形貌和磁學(xué)特性等特征進(jìn)行了研究。主要研究結(jié)果和創(chuàng)新點(diǎn)如下:1.研究了不同碳源對磷酸鐵鋰復(fù)合材料的影響,使用了五種不同的碳源(乙二醇、聚乙二醇4000、聚乙烯醇PVA-124、一水合檸檬酸和葡萄糖)通過溶膠凝膠法(sol-gel)合成LiFePO4/C復(fù)合材料。XRD研究表明樣品均為橄欖石相磷酸鐵鋰。SEM測試表明以乙二醇為碳源的樣品成多孔結(jié)構(gòu),而以葡萄糖為碳源的樣品顆粒較大,大小為40微米。VSM研究表明:一方面以聚乙烯醇(PVA-124)為碳源的樣品相對比飽和磁化強(qiáng)度最大,大小為2.01 emu/g,另一方面以乙二醇為碳源的樣品矯頑力最大,其值為170.67 Oe。2.研究了銅(Cu)對磷酸鐵鋰復(fù)合材料的影響,通過兩步法合成不同質(zhì)量比的銅和磷酸鐵鋰復(fù)合材料,并用TG、XRD、FTIR、SEM和VSM等方法對銅和磷酸鐵鋰復(fù)合材料的合成過程樣品熱特性、物相結(jié)構(gòu)、官能團(tuán)及化學(xué)鍵、微觀表面形貌和磁特性進(jìn)行了研究。表明復(fù)合材料前驅(qū)體升溫到大概400℃以后可能開始有復(fù)合材料合成。復(fù)合材料物相結(jié)構(gòu)分析出現(xiàn)明顯磷酸鐵鋰和銅單質(zhì)的主要峰型,無雜質(zhì)峰。微觀形貌SEM分析表明復(fù)合材料顆粒性明顯、分散性較好,顆粒大小主要為400 nm。室溫下測試磁滯回線表明銅單質(zhì)的引入使得復(fù)合材料的 Ms(emu/g)、Mr(emu/g)和 Area of hysteresis loop(kOe·emu/g)都有微小減小變化趨勢。3.研究二氧化錳對磷酸鐵鋰復(fù)合材料的影響,通過兩步法合成不同質(zhì)量比的二氧化錳和磷酸鐵鋰復(fù)合材料,并用TG、XRD、FTIR、SEM和VSM等方法對二氧化錳和磷酸鐵鋰復(fù)合材料的合成過程樣品熱特性、物相結(jié)構(gòu)、官能團(tuán)及化學(xué)鍵、微觀表面形貌和磁特性進(jìn)行了研究。表明復(fù)合材料前驅(qū)體升溫400℃以后可能開始有復(fù)合材料合成。復(fù)合材料物相結(jié)構(gòu)分析出現(xiàn)明顯磷酸鐵鋰和二氧化錳的主要峰型,無明顯雜質(zhì)峰型。微觀形貌SEM分析表明復(fù)合材料顆粒性明顯、分散性較好,顆粒大小主要為168 nm。室溫下測試磁滯回線表明二氧化錳的引入使得復(fù)合材料的Ms(emu/g)、Mr(emu/g)和Area of hysteresis loop(kOe·emu/g)基本上是隨著二氧化錳的增加而增加。4.研究三氧化二鋁(A1203)對磷酸鐵鋰復(fù)合材料的影響,通過兩步法合成不同質(zhì)量比的A1203和磷酸鐵鋰復(fù)合材料,并用TG、XRD、FTIR、SEM和VSM等方法對Al203和磷酸鐵鋰復(fù)合材料的合成過程樣品熱特性、物相結(jié)構(gòu)、官能團(tuán)及化學(xué)鍵、微觀表面形貌和磁特性進(jìn)行了研究。表明復(fù)合材料前驅(qū)體升溫450℃以后可能開始有復(fù)合材料合成。復(fù)合材料物相結(jié)構(gòu)分析出現(xiàn)明顯磷酸鐵鋰和Al2O3的主要峰型,沒有出現(xiàn)雜質(zhì)峰。微觀形貌SEM分析表明復(fù)合材料顆粒性明顯、分散性較好,顆粒大小主要為350 nm。室溫下測試磁滯回線表明三氧化二鋁的引入使得復(fù)合材料的Ms(emu/g)、Mr(emu/g)和Area of hysteresis loop(kOe·emu/g)都有微小變化。
[Abstract]:Lithium-ion battery cathode material olivine phosphate lithium-ion has the characteristics of no pollution to the environment, low price, rich source of raw materials, high specific energy and high safety performance. It is one of the most potential cathode materials for lithium ion batteries. However, the lithium ion battery positive material peridotite type LiFePO4 has shortcomings. The first is its accumulation density. In this way, the volume is lower than the capacity, and the volume of the battery is relatively large. Second is the ion diffusion coefficient and the low conductivity. The conductivity kappa of the material is related to the hole type polaron. The spin of the hole in the olivine type iron phosphate is related to the 2 electronic structure of the Fe3+ (TG) 3 (eg). The two valence iron cation (Fe2+), with the electronic structure of (tgT) 3 (egT) 2tg, produces ferromagnetic coupling through the double exchange mechanism, so the loss of electrons will cause the distortion of the polar subtype, and the spin polarized charge cloud will be produced. This paper uses the simple operation, the synthesis conditions easy to control, and the preparation of the sol-gel method (sol-gel), which is characterized by small particle size and so on. The lithium iron phosphate composite material was prepared by a step method, and the metal single copper and phosphite lithium carbon composites were prepared by two steps, and the AxOy metal oxides (manganese dioxide, three oxide two aluminum) and olivine type lithium carbon composites were synthesized by two steps and the synthesis process of the composites was heated by TG, XRD, FTIR, SEM, and VSM. Characteristics, phase structure, functional group and chemical bond, microsurface morphology and magnetic properties are studied. The main research results and innovation points are as follows: 1. the effects of different carbon sources on the lithium phosphate composites were studied, and five different carbon sources (ethylene glycol, polyethylene glycol 4000, polyvinyl alcohol PVA-124, monohydrate citric acid and Portuguese) were used. LiFePO4/C composite material.XRD study by sol-gel method (sol-gel) showed that the samples were all peridotite phase lithium iron phosphate.SEM test showed that the sample with ethylene glycol as carbon source was porous structure, and the sample particles with glucose as carbon source were larger, the size of 40 micron.VSM study showed that polyvinyl alcohol (PVA-124) as carbon on the one hand The relative saturation magnetization of the source samples is the largest, the size is 2.01 emu/g. On the other hand, the sample with ethylene glycol as carbon source has the greatest coercivity, and its value is 170.67 Oe.2. to study the effect of copper (Cu) on the lithium phosphate composite material. The two step method is used to synthesize copper and phosphate lithium phosphate composites with different mass ratio, and TG, XRD, FTIR, SEM and VSM are used. Methods the thermal properties, phase structure, functional group and chemical bond, micro surface morphology and magnetic properties of copper and lithium iron phosphate composites were studied. The results show that composite materials may begin to be synthesized after heating up to about 400 degrees C. The phase structure analysis of the composite material appears obvious lithium and copper phosphate. The micromorphology SEM analysis shows that the particle size of the composite is obvious and the dispersion is better. The particle size is mainly 400 nm. at room temperature and the hysteresis loop shows that the introduction of copper monomer makes the composite material Ms (emu/g), Mr (emu/g) and Area of hysteresis loop (kOe emu/g) have a slight decreasing trend. The effect of manganese dioxide on the lithium iron phosphate composite was studied. By two step method, the composite of manganese dioxide and lithium iron phosphate with different mass ratio was synthesized and the thermal properties, phase structure, functional group and chemical bond, micro surface morphology and surface morphology of manganese dioxide and lithium iron phosphate composites were prepared by means of TG, XRD, FTIR, SEM and VSM. The magnetic properties are studied. It is shown that composite materials may begin to be synthesized after heating up to 400 degrees C. The phase structure analysis of the composites appears to be the main peak type of lithium iron phosphate and manganese dioxide, and there is no obvious impurity peak type. Micromorphology SEM analysis shows that the composite has obvious particle size, good dispersibility and main particle size. To test the hysteresis loop at room temperature for 168 nm., the introduction of manganese dioxide makes the Ms (emu/g), Mr (emu/g) and Area of hysteresis loop (kOe. Emu/g) of the composite substantially increase with the increase of manganese dioxide and increase the effect of the three oxidation of two aluminum on the lithium phosphate composite material, and the synthesis of different mass ratios by the two step method. The thermal properties, phase structure, functional group and chemical bond, microsurface morphology and magnetic properties of the samples of Al203 and lithium iron phosphate composites are studied by means of A1203 and TG, XRD, FTIR, SEM and VSM. The results show that composite materials may begin to be synthesized after heating up to 450 degrees C. The main peak type of lithium iron phosphate and Al2O3 was found in the phase structure analysis of the composites, and no impurity peaks were found. Micromorphology SEM analysis showed that the composites were granular and dispersed well. The size of the particles was 350 nm. at room temperature and the hysteresis loop showed that the introduction of three oxidation two aluminum made the composite Ms (emu/g), Mr (emu/g) and the composite material. There are slight changes in Area of hysteresis loop (kOe. Emu/g).
【學(xué)位授予單位】：廣西師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33;TM912
[Abstract]:Lithium-ion battery cathode material olivine phosphate lithium-ion has the characteristics of no pollution to the environment, low price, rich source of raw materials, high specific energy and high safety performance. It is one of the most potential cathode materials for lithium ion batteries. However, the lithium ion battery positive material peridotite type LiFePO4 has shortcomings. The first is its accumulation density. In this way, the volume is lower than the capacity, and the volume of the battery is relatively large. Second is the ion diffusion coefficient and the low conductivity. The conductivity kappa of the material is related to the hole type polaron. The spin of the hole in the olivine type iron phosphate is related to the 2 electronic structure of the Fe3+ (TG) 3 (eg). The two valence iron cation (Fe2+), with the electronic structure of (tgT) 3 (egT) 2tg, produces ferromagnetic coupling through the double exchange mechanism, so the loss of electrons will cause the distortion of the polar subtype, and the spin polarized charge cloud will be produced. This paper uses the simple operation, the synthesis conditions easy to control, and the preparation of the sol-gel method (sol-gel), which is characterized by small particle size and so on. The lithium iron phosphate composite material was prepared by a step method, and the metal single copper and phosphite lithium carbon composites were prepared by two steps, and the AxOy metal oxides (manganese dioxide, three oxide two aluminum) and olivine type lithium carbon composites were synthesized by two steps and the synthesis process of the composites was heated by TG, XRD, FTIR, SEM, and VSM. Characteristics, phase structure, functional group and chemical bond, microsurface morphology and magnetic properties are studied. The main research results and innovation points are as follows: 1. the effects of different carbon sources on the lithium phosphate composites were studied, and five different carbon sources (ethylene glycol, polyethylene glycol 4000, polyvinyl alcohol PVA-124, monohydrate citric acid and Portuguese) were used. LiFePO4/C composite material.XRD study by sol-gel method (sol-gel) showed that the samples were all peridotite phase lithium iron phosphate.SEM test showed that the sample with ethylene glycol as carbon source was porous structure, and the sample particles with glucose as carbon source were larger, the size of 40 micron.VSM study showed that polyvinyl alcohol (PVA-124) as carbon on the one hand The relative saturation magnetization of the source samples is the largest, the size is 2.01 emu/g. On the other hand, the sample with ethylene glycol as carbon source has the greatest coercivity, and its value is 170.67 Oe.2. to study the effect of copper (Cu) on the lithium phosphate composite material. The two step method is used to synthesize copper and phosphate lithium phosphate composites with different mass ratio, and TG, XRD, FTIR, SEM and VSM are used. Methods the thermal properties, phase structure, functional group and chemical bond, micro surface morphology and magnetic properties of copper and lithium iron phosphate composites were studied. The results show that composite materials may begin to be synthesized after heating up to about 400 degrees C. The phase structure analysis of the composite material appears obvious lithium and copper phosphate. The micromorphology SEM analysis shows that the particle size of the composite is obvious and the dispersion is better. The particle size is mainly 400 nm. at room temperature and the hysteresis loop shows that the introduction of copper monomer makes the composite material Ms (emu/g), Mr (emu/g) and Area of hysteresis loop (kOe emu/g) have a slight decreasing trend. The effect of manganese dioxide on the lithium iron phosphate composite was studied. By two step method, the composite of manganese dioxide and lithium iron phosphate with different mass ratio was synthesized and the thermal properties, phase structure, functional group and chemical bond, micro surface morphology and surface morphology of manganese dioxide and lithium iron phosphate composites were prepared by means of TG, XRD, FTIR, SEM and VSM. The magnetic properties are studied. It is shown that composite materials may begin to be synthesized after heating up to 400 degrees C. The phase structure analysis of the composites appears to be the main peak type of lithium iron phosphate and manganese dioxide, and there is no obvious impurity peak type. Micromorphology SEM analysis shows that the composite has obvious particle size, good dispersibility and main particle size. To test the hysteresis loop at room temperature for 168 nm., the introduction of manganese dioxide makes the Ms (emu/g), Mr (emu/g) and Area of hysteresis loop (kOe. Emu/g) of the composite substantially increase with the increase of manganese dioxide and increase the effect of the three oxidation of two aluminum on the lithium phosphate composite material, and the synthesis of different mass ratios by the two step method. The thermal properties, phase structure, functional group and chemical bond, microsurface morphology and magnetic properties of the samples of Al203 and lithium iron phosphate composites are studied by means of A1203 and TG, XRD, FTIR, SEM and VSM. The results show that composite materials may begin to be synthesized after heating up to 450 degrees C. The main peak type of lithium iron phosphate and Al2O3 was found in the phase structure analysis of the composites, and no impurity peaks were found. Micromorphology SEM analysis showed that the composites were granular and dispersed well. The size of the particles was 350 nm. at room temperature and the hysteresis loop showed that the introduction of three oxidation two aluminum made the composite Ms (emu/g), Mr (emu/g) and the composite material. There are slight changes in Area of hysteresis loop (kOe. Emu/g).
【學(xué)位授予單位】：廣西師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33;TM912
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