Vertical Integration of Multi-Electrodes Inside a Single Sheet of Paper and the Control of the Equivalent Circuit for High-Density Flexible Supercapacitors

Paper is an excellent substrate for flexible devices due to its various advantages such as flexibility, porosity, lightness, and thinness. Its inherent characteristics can be also exploited to overcome the limitations of con-ventional substrates, such as weak adhesion and large mass densities. Here, we propose a method for fabricating vertically integrated multi-electrodes within only a single sheet of paper. Despite the randomly distributed fibrous networks in a paper, the multi-layered electrodes were uniformly formed and completely separated by applying a removable hydrophobic wax barrier confinement inside a single sheet of paper. The integrated multi-layer electrodes inside a single sheet of paper mean that conventional two-dimensional planes can be used as three-dimensional scaffolds. The highly integrated electrodes and circuit systems are located within only a sheet of paper, making a new possibility to design maximizing the energy storage performance, integrated circuit systems, and significantly decreasing the thickness of the system without external complex structure. In conse-quence, this unique platform can circumvent most of the fabrication challenges related to two-dimensional energy storage sheets.