磷酸钒锂在多电子反应过程中的结构变化和动力学行为

项目名称： 磷酸钒锂在多电子反应过程中的结构变化和动力学行为

项目编号： No.51274075

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 矿业工程

项目作者： 戴长松

作者单位： 哈尔滨工业大学

项目金额： 80万元

中文摘要： 针对磷酸钒锂电池在三电子反应过程中循环稳定性差的问题，采用碳热还原法制备磷酸钒锂基正极材料，研究制备参数、离子掺杂和包覆碳与其充放电性能的对应规律；通过XRD结构精修、X射线吸收精细结构、中子散射（neutron diffraetion）和TEM测试，表征锂离子嵌脱对磷酸钒锂精细结构的影响，分析Li位、V位、P位和O位的占位情况；采用电化学阻抗、循环伏安、恒电流间歇滴定以及结构分析手段，揭示多电子反应对材料精细结构以及动力学行为的影响规律；明确磷酸钒锂颗粒大小、掺杂离子和包覆碳对其电子导电性、离子导电性、锂离子扩散系数、电极/电解液界面阻抗和电化学反应电阻影响规律；弄清多电子反应情况下，磷酸钒锂循环稳定性的影响机制及改进措施，为高性能磷酸盐正极材料的设计提供理论依据。

中文关键词： 磷酸钒锂；多电子交换；掺杂；包覆；循环稳定性

英文摘要： In order to solve the problem of the capacity fading of Li3V2(PO4)3 during the process of three-electron reaction, Li3V2(PO4)3-based cathode materials are prepared using carbothermal reduction process to study the ralationship between charge-discharge performance and the synthesising technology, such as producing parameters, ion doping and cabon coating. XRD refinment, X-ray absorption fine structure, neutron diffraction and TEM are employed to study the influence of Li+ intercalation/deintercalation on the structure of lithium vanadium phosphate, and analyse the occupied condition at Li-site, V-site, P-site and O-site. EIS, CV, GITT and structure analysis are adopted to explain the influence of multi-electron reaction on the fine strucure and kinetic properties of cathode materials. It would be verifed that how the particle-size, ion-doping and carbon-coating of Li3V2(PO4)3 material influence the electro conductivity, ion conductivity, Li-ion diffusion coefficient, resistance of the electrode/electrolyte interface and electrochemical reaction resistance. The influence mechanism and improving method of the cycling stability of Li3V2(PO4)3 material are clarified during the process of multi-electron reaction, so as to provide theory basis of designing high-performance phosphate cathode materials.

英文关键词： Lithium vanadium phosphate；Multi-electron exchange；Element doping；Coating；Cycle stability