磷酸亚铁锂的合成与改性研究
发布时间：2018-07-20 13:07
【摘要】：锂离子电池（LIBs）具有高功率密度、高能量密度等优点，并且其在电动汽车、移动设备、医疗和手机等各个领域应用广泛。锂离子电池（LIBs）的正极材料在其结构中又占有举足轻重的地位，而橄榄石状的磷酸亚铁锂因为具有优良的电化学性能以及价格低廉、无毒、优良的热稳定性、环境友好等优点受到广泛的关注，但是磷酸亚铁锂的应用因低的离子电导率和低的导电性这些缺点而受到限制，通过提高磷酸亚铁锂的导电性和控制颗粒尺寸来提高锂离子电池的电化学性能显得尤为重要。 本论文主要从两个方面对磷酸亚铁锂进行了改性研究。利用X射线衍射仪（XRD），扫描电子显微镜（SEM）对材料晶体结构、表观形貌和化学成分进行了分析表征，以观察颗粒的尺寸与形貌，分析表面形貌对材料性能的影响，从而优化材料的电化学性能；采用恒电流充放电测试技术对其电化学性能进行测定分析，探索了最佳条件下的合成方法。 （1）采用传统的固相法合成锂离子电池正极材料LiFePO4/C，加入乙二醇进行表面改性，并且研究了在不同的煅烧温度（650℃，700℃，750℃）下，乙二醇对LiFePO4/C颗粒形貌的影响。在700℃下经乙二醇改性的LiFePO4/C颗粒呈板状堆积，在不同的电流密度下充放电平台稳定，并且具有较好的循环效率。 （2）利用水热法和后期煅烧的方法合成镍掺杂的LiFe1-xNixPO4/C （x=0.05，0.1，0.15）。Ni2+掺杂的样品的颗粒尺寸为400-500nm，具有良好的结晶度和颗粒形貌，其中LiFe0.9Ni0.1PO4具有更好的晶体结构和电化学性能，在0.1C倍率下的放电比容量达到150mAh·g1，，在0.1mV/s扫描速率下氧化还原峰的电势差较小，具有更好的可逆性和更高的导电性。
[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
本文编号：2133619
[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
本文编号：2133619
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