聚阴离子型高性能钠离子电池正极材料结构调控与电化学机理研究

Sodium ion battery has been considered as the most attractive alternative to lithium-ion batteries for portable electronic devices and large-scale energy storage on account of its rich resources and low cost. Therefore, it is a great challenge to explore the environmental friendly electrode materials for sodium batteries with abundant resources, low cost and excellent electrochemical properties. Among them, polyanionic compounds are favored by numerous researchers worldwide because of their stable structure and large ion diffusion channels. However, their inherent defects, such as low electrical conductivity and low theoretical special capacity, greatly limit the pace of their practical application. This project intends to construct polyanion-type cathode materials with a unique micro/nano-structure through innovative design for phase structure and special synthesis methods, and to exploit novel polyanionic compounds with enhanced electrode/electron conductivity and excellent electrochemical performance. Moreover, not only a systematic study of the charge-discharge mechanism and kinetic behavior of the relevant electrode materials, but also an in-depth investigation of intrinsic relationship between the structure and electrochemical performance will be conducted. On this basis above, a series of sodium ion full cells with excellent electrochemical performance will be developed.

钠离子电池因其具有原材料资源丰富、价格低廉等突出优点，近年来被视为是继锂离子电池之后可作为便捷式电子器件电源及大规模储能系统的理想体系。因此，探寻资源丰富、经济环保具有优良电化学性能的储钠电极材料已成为当前的一个研究重点和难点。聚阴离子型化合物因具有更稳定的结构和更大的离子扩散通道等特性备受各国科学家的青睐。虽然其在理论上具有很好的应用前景，但电子导电性和理论容量偏低等固有缺陷极大的限制了其走向实际应用。本项目拟通过体相结构设计离子掺杂改性及特殊的合成方法构筑具有独特微纳结构的钠离子电池用聚阴离子型正极材料，并探索其电化学性能与多层级结构之间的本征关系，制备出具有优异电化学性能的新型聚阴离子化合物，实现电极材料电子/离子导电性的提升，从而有效改善电极体系的综合电化学性能，并对相关电极材料的充放电反应机理及动力学行为进行系统研究，在此基础上研发出具有优异电化学性能的钠离子全电池。

钠离子电池因其资源丰富、成本低廉及安全高效等突出优点，在电化学规模储能和低速交通领域具有广阔的应用前景。但钠离子电池仍面临能量密度低、循环寿命短的问题，开发高性能正极材料是其性能提升的主要突破点之一。课题以聚阴离子型钠离子电池正极材料为研究对象，围绕其电子导电性差和理论容量偏低的关键科学问题，通过体相结构设计、离子掺杂改性及创新合成方法开发了系列新型聚阴离子型化合物，包括Na3V2(PO4)3/C分级微球、Na4MnV(PO4)3/C复合材料、Na3+xMnxV2-x(PO4)3/C复合材料、碳量子点修饰Na3V2(PO4)2F3、Na4Fe3(PO4)2(P2O7)/C纤维等，实现了电极材料电子/离子导电性的提升，有效改善电极体系的综合电化学性能，并对相关电极材料的充放电反应机理及动力学行为进行系统研究。进一步将优选的聚阴离子正极材料与商业硬碳负极匹配，试制了钠离子全电池，为规模储能用钠离子电池关键技术的发展奠定科学与材料基础。