静电纺丝法制备磷酸盐系锂离子电池正极材料

发布时间：2018-04-16 19:30

本文选题：LiFePO_4/C + Li_3V_2(PO_4)_3/C　；参考：《哈尔滨工业大学》2011年硕士论文

【摘要】：伴随着科技的不断进步,能源与环境问题日趋严重,这就对电池产业提出了更高的要求。锂离子电池因其具有的良好的电池性能和绿色环保特性而备受推崇。现在锂离子电池发展的关键就是正极材料。磷酸盐系正极材料凭借其电化学性能良好、结构稳定、安全性好、价格低等优点而引起了广泛关注。磷酸盐系正极材料的电子导电率和离子导电率均较低,这是限制其进一步发展的最大阻碍。本文对锂离子电池的情况进行了概述并对锂离子电池正极材料的发展现状及存在问题进行了详细评述。研究了使用静电纺丝法制备磷酸盐系锂离子电池正极材料的工艺条件,并对所得的磷酸铁锂和磷酸钒锂材料通过SEM、XRD和电化学测试等手段对材料的表面微观形貌、晶体结构和电化学性能等进行了考察。采用静电纺丝法制备了LiFePO_4/C和掺杂石墨的LiFePO_4/C纳米材料。通过调整无机盐和聚乙烯吡咯烷酮的含量配制了多种前驱液,获取了多种纺丝材料。通过烧结后的SEM测试结果来看,PVP的量对于材料的棒状形貌保持有很重要的作用。掺杂石墨首先可以提高纺丝效果,其次可以大幅度提高材料的电子电导。另外通过加入光照加热的手段来减少材料的胶粘现象,通过这一手段制备出的材料的首次放电容量达到了154mAh/g。采用静电纺丝法制备了Li_3V_2(PO_4)_3/C纳米材料。通过不断调整确定了基础的前驱液配制方案,并在此基础之上进行了大量的改进工作。从烧结材料的SEM图像来看,材料的形貌从最初的块状形貌变为了小的颗粒,但始终无法形成棒状形貌。采用静电纺丝法制备了LiFe_xV_(1-x)PO_4和LiFePO_4/Li_3V_2(PO_4)_3的同轴复合材料。从SEM结果来看,LiFe_xV_(1-x)PO_4材料的形貌基本为良好的棒状形貌,掺杂后材料的电化学性能有了明显提升。同轴复合材料在形貌上则是不规则的,为棒状和小颗粒相互粘连的。这种材料的循环伏安曲线同时存在着LiFePO_4和Li_3V_2(PO_4)_3的氧化还原峰,说明两种材料都形成了完整的晶形。
[Abstract]:With the development of science and technology, energy and environment problems become more and more serious, which puts forward higher requirements for battery industry.Lithium ion batteries are highly praised for their good battery performance and green environmental protection.The key to the development of lithium-ion batteries is cathode materials.Phosphate cathode materials have attracted wide attention due to their good electrochemical properties, stable structure, good safety and low price.The electronic conductivity and ionic conductivity of phosphate cathode materials are low, which is the biggest hindrance to their further development.In this paper, the situation of lithium ion battery is summarized, and the development status and existing problems of cathode material for lithium ion battery are reviewed in detail.The preparation conditions of cathode materials for phosphate-based lithium ion batteries by electrospinning method were studied. The surface morphology of the materials were investigated by means of SEM XRD and electrochemical measurements.The crystal structure and electrochemical properties were investigated.LiFePO_4/C and graphite doped LiFePO_4/C nanomaterials were prepared by electrostatic spinning.By adjusting the contents of inorganic salts and polyvinylpyrrolidone, a variety of precursor fluids were prepared and various spinning materials were obtained.The results of sintered SEM show that the amount of SEM plays an important role in maintaining the rod-like morphology of the materials.The doped graphite can improve the spinning effect first, and then the electronic conductivity of the material can be greatly improved.In addition, the adhesive phenomenon was reduced by adding light heating, and the first discharge capacity of the material was up to 154mAh/ g.Li_3V_2(PO_4)_3/C nanomaterials were prepared by electrostatic spinning.Through continuous adjustment, the basic precursor formulation scheme is determined, and a lot of improvement work is carried out on this basis.From the SEM images of the sintered materials, the morphology of the sintered materials changed from the initial bulk morphology to the small particles, but the rod morphology could not be formed at all times.Coaxial composites of LiFe_xV_(1-x)PO_4 and LiFePO_4/Li_3V_2(PO_4)_3 were prepared by electrostatic spinning.The results of SEM show that the morphology of LiFex\\\ -\\\The coaxial composites are irregular in morphology and stick and small particles adhere to each other.The redox peaks of LiFePO_4 and Li_3V_2(PO_4)_3 exist at the same time in the cyclic voltammetry curve of this material, which indicates that both materials form a complete crystal shape.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TM912.9

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