基于配位聚合物超长纳米线的柔性电极材料的制备和性能研究

The emerging and application of flexible energy storage devices have tremendously boosted the development of multifunctional electronics. However, challenges still exist in the pursuit of high-performance electrode materials. Vacuum filtration is a widely used method to prepare flexible film electrode which contains nano-carbon materials and electrochemical active materials. However, the self-supported flexible graphene composite film prepared by this method usually shows poor structure stability, limited flexibility and mechanical performance, which further leads to the uncomprehensive utilization of the energy storage ability derived from the electrochemical active materials. Therefore, the present project is motivated by the need to develop a simple and effective approach to fabricate flexible electrode with enhanced flexibility and energy storage performance. Firstly, coordination polymer nanowires with high dispersity and affinity with graphene oxide solutions would be prepared, followed by vacuum filtrating with graphene oxide to form composite film. Then, high temperature treatment would be applied to the composite film in order to transform coordination polymer nanowires into metal oxide nanowires and graphene oxide into reduced graphene oxide. It is anticipated that the resulted flexible composite film would show homogeneous microstructure, excellent flexibility and capacitance performance.

柔性储能器件的开发和应用大大促进了电子产品的多功能化，发展高性能电极材料是柔性储能器件发展的关键所在。通过真空抽滤氧化石墨烯与赝电容活性物质的分散液制备柔性薄膜电极是一种被广泛采用的柔性电极制备方法。而该方法所制备的石墨烯自支撑柔性复合薄膜电极普遍存在由于活性物质与氧化石墨烯亲和性差引起的薄膜分层、材料整体柔性、力学性能差的问题，从而进一步导致活性储能物质的储能能力无法充分发挥。从提高柔性薄膜电极储能性能、电化学稳定性和柔性的角度出发，本项目拟研究制备一种与氧化石墨烯分散液有良好相容性和分散性的柔性配位聚合物超长纳米线，采用真空抽滤法将配位聚合物纳米线与氧化石墨烯复合制备高质量柔性电极薄膜，并最终通过煅烧处理还原氧化石墨烯，同时将配位聚合物纳米线转换为金属氧化物纳米线，从而得到微结构均匀良好的电极材料，在保证电极材料具有优异柔性的基础上，实现薄膜电极的高导电和高比容量。

针对真空抽滤法所制备的石墨烯自支撑柔性复合薄膜电极普遍存在的材料整体柔性差的问题，同时从提高柔性薄膜电极储能性能和电化学稳定性的角度出发，本项目研究制备了与氧化石墨烯分散液有良好相容性和分散性的柔性金属配位聚合物超长纳米线，并通过与氧化石墨烯共同抽滤，并辅以硫化和煅烧处理，获得了柔性金属硫化物/还原氧化石墨烯复合薄膜电极，在保证电极材料具有优异柔性的基础上，实现薄膜电极的高导电和高比容量。此外，采用金属配位聚合物纳米线为基体和前驱体，通过一锅水热法，制得了具有多级结构的中空纳米纤维，并将该纤维应用于柔性超级电容器、锂离子电池和钠离子电池的储能应用中。实验结果表明：（1）所制得金属硫化物/石墨烯柔性薄膜材料在电流密度为0.5 A g-1时，其质量比容量可达1279 F g-1，当电流密度提高到10 A g-1，质量比电容仍然保持在608 F g-1；（2）所制得的多级结构中空纳米纤维在用作超级电容器电极材料时，表现出579 F g-1的比电容。将其组装成非对称柔性超级电容器，在10000次充/放电循环中表现出96.5%的高电容保持率，表明其具有出色的循环稳定性。此外，该电极材料机械形变耐久性优异，在50次机械弯曲中可以保持稳定的储能性能；（3）所制得的多级结构中空纳米纤维电极在作为锂/钠离子电池负极材料，展现出优异的倍率性能和循环寿命。在1000 mA g-1电流密度下循环500圈，锂离子电池和钠离子电池的可逆放电比容量仍可保持84.1%和88.4%以上。此外，动力学分析表明，该电极材料的锂/钠离子存储过程主要受赝电容行为控制。. 在项目执行期间，发表了高水平学术论文11篇，其中SCI收录11篇；申请国家发明专利1项，已授权1项；项目投入经费25.30万元，支出经费19.31万元，结余经费5.98万元，剩余经费计划用于本项目研究后续支出。