新型共轭高分子正极材料的制备及基础研究

Organic sodium-ion batteries, as promising alternatives of commercial inorganic lithium-ion batteries, have attracted more and more attention for the foreseeable large-scale applications (especially the burgeoning electric vehicles and flexible and wearable electronics), because organic sodium-ion batteries can combine the merits of SIBs (similar electrochemical properties compared with lithium-ion batteries but having environmental benignity and vast resources) and the advantages of organic materials (flexibility, natural sources, recyclability, low cost, and easily functionalized for tuning the electrochemical performance, compared with inorganic materials). However, till now, only a few organic materials have been reported for sodium-ion batteries, especially for the cathode materials. Even worse, most of them are suffering low capacity, low power density and short cyclability etc. Facing these challenges, this proposal is dedicated to develop high performance organic sodium-ion batteries, through design and synthesis of novel polymeric cathode materials. Furthermore, the structure-property relationship and inner mechanism will be intensively studied by investigating the effects of conjugation, polydispersity, electron-withdrawing group and constitutional isomers on electrochemical performance. The implement of this proposal is expected to arouse growing interests of organic materials for sodium-ion batteries with functional molecular design towards high performance and pave a way to achieve large-scale application of organic sodium-ion batteries.

随着便携电子设备和电动汽车的兴起，锂电池的需求成指数增加。因此，国际上加大了锂电池替代品的研究。其中，钠离子电池吸引了巨大的关注。但钠离子的尺寸远大于锂离子，钠离子的嵌入很容易造成无机电极材料的破坏。所以，有机钠离子电池作为商用无机锂离子电池的替代品对未来的大规模应用具有诱人的前景。但有机钠离子电池，特别是正极材料的研究刚刚起步，还面临着容量低、功率密度低、循环寿命短以及结构性能关系不明确等问题。本项目致力于发展新型高性能共轭高分子正极材料，通过化学修饰实现对材料电化学性能的调控。在对其分子量均一性、聚合度和结构进行有效调控的同时，研究共轭性、聚合度、吸电子基团和构造异构体对于电池性能的影响，探索氢键在提高有机离子电池性能方面的新用途和决定高分子材料电压平台的新规律，为结构与性能关系的研究、储能机理的探索和高性能有机钠离子电池的构筑奠定基础，从而推动有机钠离子电池在能源存储等领域的应用。

本项目针对有机钠离子电池中有机正极材料存在的容量低、功率密度低、循环寿命短等问题，展开研究。以发展高性能有机钠离子电池为总目标，合理设计共轭聚合物正极材料，通过化学修饰实现对材料电化学性能的调控。在对其分子量均一性、聚合度和结构进行有效调控的同时，研究共轭性、聚合度、吸电子基团和构造异构体对于电池性能的影响。研究表明：扩大材料的共轭体系，有利于提高材料的容量和快充性能；通过利用p型电极材料，并设计大共轭体系，可以获得高输出电压的正极材料，进而可以提高其功率密度；通过引入氢键可以一定程度上解决小分子正极材料的溶解问题，同时，获得了空气稳定的小分子间位苯醌式结构；并在此基础上，进一步扩大材料的共轭体系，电池的容量和稳定性均大幅提高。这些结果加深了对有机高分子材料的储能机制的理解，并进而开发了一系列提高有机电池性能的新方法。项目执行以来，发表高水平期刊论文38篇，包括Chem. Soc. Rev.，Acc. Chem. Res.，Chem（2篇），Angew. Chem.（5篇），CCS Chem，Energy Environ. Sci.，Energy Storage Mater.，J. Mater. Chem. A（6篇），Energy Environ. Mater.等。申请发明专利5项，已获批2项。培养博士后3人，已出站1人；培养博士生和硕士生20人，包括已毕业11人。入选2020年度Journal of Materials Chemistry A Emerging Investigators，2020年度RSC高被引作者等。