基于电纺聚酰亚胺纳米纤维的高容量电极材料制备及其电化学反应机理研究

In this project, it is proposed to prepare composite nanofibers of polyimide/graphene or carbon nanotubes with certain conductivity by in-situ polycondensation and electrospinning technology, and cut the nanofibers into ultra-short nanofibers; The ultra-short composite nanofibers of polyimide/graphene or carbon nanotubeswere were coated to make a fiber electrode, which was then assembled into a lithium ion battery with a lithium metal foil as a negative electrode. The electrochemical cell was tested using the electrochemical equipment such as electrochemical workstation and charge and discharge test system. Since the diamine structure in the polyimide molecule contains a carbonyl or hydroxyl group, the high storage capacity characteristic is fully demonstrated. The micro-gap of the interface between the polyimide and the conductive graphene or the carbon nanotubes in the nanofibers and the interfacial cracks between the nanofibers and the binder in the electrode constitute a microstructure channel system for the diffusion of the lithium ions in the electrolyte so that the diffusion efficiency of the electrolyte in the polyimide nanofiber electrode is good. And finally achieve the polyimide nanofiber electrode material with high specific capacity, high rate characteristics and excellent cycle performance and other characteristics.

本项目研究拟采用原位缩合聚合和静电纺丝技术制备具有一定导电性的聚酰亚胺/石墨烯或碳纳米管复合纳米纤维，并切割粉碎成超短纳米纤维；用浆料涂布技术制备这种聚酰亚胺/石墨烯或碳纳米管复合纳米纤维短纤电极片，并以金属锂箔为负极组装成锂离子电池；用电化学工作站及充放电测试系统等电化学设备对这种电池进行电化学性能测试；由于聚酰亚胺分子中的二胺结构中含有极性较大的羰基或羟基，致使其高储电容量特性得到充分展现；纳米纤维中聚酰亚胺与导电剂石墨烯或碳纳米管之间界面上的缝隙及电池极片中纳米纤维与粘结剂之间的界面缝隙，构成了电解液扩散的微结构通道系统，使电解液在聚酰亚胺纳米纤维极片中的扩散效率良好。最终实现聚酰亚胺纳米纤维电极材料的高比容量、高倍率特性和优良的循环性能等特性。

本项目研究基本上执行了计划任务书中所提出各项年度计划，制备了多种聚酰胺酸溶液，并与导电剂复合后和热亚胺化，形成具有一定导电性能的高性能聚合物电极材料，并用此电极材料制备了一系列纽扣电池，通过对这些纽扣电池的电化学性能测试，评估了聚酰亚胺等有机聚合物材料的电化学活性及其电化学存储功能，得出了传统有机绝缘聚合物材料聚酰亚胺等具有较高电化学活性和高储电容量的结论，打破了人们对高绝缘有机聚合物材料的固有观念，开劈了制备新能源电池电极材料的新途径。适度改善其导电性能后的聚酰亚胺电极材料的比电容量是传统石墨比电容量的3倍有余，有希望在新能源锂离子电池领域得到广泛应用。本项目研究取得了丰硕的成果，发表16篇相关学术论文，申请并获得授权国家发明专利5项。本项目研究很好地实现了大幅度提升锂离子电池的比容量，显著改善锂离子电池的倍率性能和循环稳定性能等研究目标。