柔性超级电容器石墨烯图形化电极的模板热场诱导成形基础研究

As the flag of next-generation flexible energy storage, graphene-based supercapacitors will be found extended applications in fields of flexible displays, wearable electronics or portable electronics in the future. However, the technique for manufacturing graphene-based flexible supercapacitor is now faced with a difficulty in less of the ability for low-costly and high-throughputly mass-producing patterned graphene electrodes. This research proposal proposes a technique of patterning graphene by contacting a hot-template with the graphene oxide film to thermally generate a patterned electrode of reduced graphene oxide. Based on this technique, a role-to-role (R2R) process is developed in this proposal for mass-producing the patterned electrodes of reduced graphene oxide. Furthermore, in order to solve another problem that sol electrolyte can not spontaneously fulfill the dewetting pores in the electrode of reduced graphene which always results in poor energy density of supercapacitors, this proposal provides an electric-field-assisted blading process where the electrohydrodynamic force will drive the sol electrolyte quickly into the electrically-wetted pores in the reduced graphene electrodes. This research focuses on the investigation of three basic issues, including the law about complex heat transfer in micro scale among multi-materials and multi-interfaces, the law about rheology of sol electrolyte in micro space under the influence of external electric field, and the control and optimization of the properties of supercapacitors in electrochemistry and interfacial mechanics. The ultimate aim of this research is to solve the bottleneck problem in manufacturing graphene-based flexible supercapacitors, and finally develop an original technique of low cost and high throughput for mass-producing flexible supercapacitors.

以石墨烯超级电容器为代表的下一代柔性电能存装置，在柔性显示、可穿戴电子、可移动电子等领域具有广泛的应用前景，然而如何在柔性衬底表面低成本、高效率的制造石墨烯微电极图形，一直是制约柔性超级电容器发展的关键瓶颈。为此本项目提出了石墨烯图形化电极的模板热场诱导成形技术，利用高温模板在氧化石墨烯薄膜中形成的大梯度温度场，可对其定域诱导还原并“卷对卷”的实现图形化石墨烯电极的规模化制造；此外，针对溶胶电解质在疏水多孔石墨烯表面难浸润而影响储能密度的问题，本项目提出了电场辅助的刮涂填充方法，利用电场增强的界面润湿效应实现溶胶电解质对石墨烯电极孔隙的有效填充。本项目将探索微细尺度下的多材料/多界面耦合传热规律、外电场作用下的溶胶电解质在纳米尺度空间的流变规律、石墨烯超级电容器的电化学和界面力学性能调制等基础科学问题，突破制约柔性超级电容器规模化制造的关键瓶颈，发展一种原创性的柔性超级电容器高效制造技术。

该项目揭示了模板热压印过程中的传热传质规律，开发了一种图形化石墨烯电极的模板热压印工艺，实现了石墨烯图形化微电极的大幅面高效率压印制造，解决了石墨烯微电极的制造效率瓶颈。另一方面，该项目揭示了器件的力学/电学特性对固态电解质填充的依赖关系，阐明了固态电解质对大厚度电极孔隙难填充的物理机制，开发了一种固态电解质对大厚度多孔电极的“自下而上”填充方法，使填充深度由原来的 5 微米以内提高到 500 微米以上，极大程度提高了全固态超级电容器的电学性能和机械性能。例如，在电学性能方面可使 500 微米厚碳纳米管电极的单位面积电容提高 45 倍以上，比目前国际上报道的最大值高出 5 倍；在力学性能方面可使 150 微米厚的碳纳米管电极在 0.5mm 曲率半径下无裂纹产生，使全固态柔性超级电容器往复弯曲 5000 次而保持其初始电容值的 95%以上。该项目在石墨烯图形化电极的规模化加工、固态电解质填充等方面的研究成果，为全固态柔性超级电容在柔性电子系统、可穿戴电子设备方面的应用提供了技术支撑。