高电导率、高倍率性能LiVPO4F/C复合正极材料的结构调控及其电化学性能研究

项目名称： 高电导率、高倍率性能LiVPO4F/C复合正极材料的结构调控及其电化学性能研究

项目编号： No.51472082

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 范长岭

作者单位： 湖南大学

项目金额： 83万元

中文摘要： 常用锂离子电池正极材料各有不足之处，新发展起来的LiVPO4F不仅含有三维扩散通道和4.2V的电压平台，还具有优异的热稳定性。但其电导率较低，通常采用两步碳热还原法制备时还含有过量的碳粉。为此，本项目围绕改善其电导率和电化学性能开展工作。采用新型一步碳热还原法制备LiVPO4F，探索影响因素对其微观结构的作用机理；选择铝、铬、钛、钇等的氧化物或氟化物作为掺杂原料，用以稳定LiVPO4F的晶体结构、改善晶格的离子电导率；探讨聚乙烯醇、酚醛树脂、环氧树脂和环氧酚醛树脂等碳源对正极电导率和电化学性能的影响；添加能加速碳源热解的促进剂，加快包覆炭中石墨微晶的生长，改善活性材料的电子电导率和电化学性能。研究将实现对LiVPO4F/C的结构调控，掌握其结构、电化学性能与制备工艺之间的内在关系，制备电导率高、杂质含量低、性能优异的正极材料，从而满足动力锂离子电池的要求。

中文关键词： 锂离子电池；正极材料；结构调控；电导率；电化学性能

英文摘要： The commonly used cathodes of lithium ion batteries possess their different shortcomings. The newly developed LiVPO4F contains not only three dimensional diffusion channels and potential platform around 4.2V, but also possesses excellent thermal stability. However, its conductivity are very low and it contains excessive carbon powders, which is prepared by the typical two step carbothermal reduction method. Therefore, this project will be carried out in order to improve its conductivity and electrochemical performances. The new style one step carbothermal reduction method will be adopted to prepare LiVPO4F and the influencing mechanisms of the factors on the microstructures will be explored. The oxide or fluoride of aluminium, chromium, titanium and yttrium will be selected as doping materials to stabilize the crystallite structure and enhance the ionic conductivity of lattice. The influences of the carbon sources of polyvinyl alcohol, phenolic resin, epoxy resin and epoxy novolac resin on the conductivity and electrochemical performances of cathode will be discussed. The accelerating agents, which can accelerate the pyrolysis of carbon sources, will be added in order to accelerate the growth of the graphite crystallite in the coated carbon and enhance the electronic conductivity and the electrochemical performances. The investigations in this project will realize the structural regulation of LiVPO4F/C. The relationships between the structure, electrochemical performances and synthesis technologies will be grasped. The cathode with high conductivity, low concentration of impurities and excellent performances will be synthesized. These will satisfy the demands of power lithium ion batteries.

英文关键词： Lithium ion batteries;cathode;structural regulation;conductivity;electrochemical performances