Supercapacitors are promising energy storage devices due to their high power density and long cycle-life, which store the electrical energy at the electrode/electrolyte interface by means of reversible ion adsorption at high-surface-area porous carbon electrodes. Although supercapacitors have been significantly advanced by fabricating nanostructured materials, and developing thin-film manufacture technologies and device architectures, their energy densities are not comparable with those of lithium thin-film batteries. Compared to traditional supercapacitors based on the activated carbon material, the graphene supercapacitors show significantly advanced performance due to the larger surface area and higher ionic conductivity[1, 2]. On the other hand, the geometric design of the supercapacitors play a key role in determining the mean ionic path to decide the performance of the supercapacitors. It has been demonstrated that the interdigital supercapacitor design is advantageous over the traditional sandwich design due to the shortened mean ionic path[3]. In addition, the power and energy density increase as the width and the interspace of the electrodes decrease in the interdigital structure, which enlarge the lateral capacitance. Furthermore, the interdigital design can be ultrathin due to the removal of the additional separator layer. 

Here we demonstrate the fabrication of thin-film planar interdigital supercapacitors by using a high-spatial-resolution laser 3D printing technique, in which the porous graphene electrodes are produced by laser photo-reduction of graphene oxide. In this way, the interspace and the width of the electrodes are accurately controlled by the laser patterning at nanometer scale precision to shorten the mean ionic path and boost the lateral capacitance. The scanning electron microscopic image of the thin-film supercapacitor is shown Fig. 1. Through tuning the dimension of the patterned electrodes, the performance of the supercapacitor can be optimized, leading to high capacitance of 16 mF/cm2 exceeding the state-of-the-art laser fabricated graphene supercapacitor[3]. 

Supercapacitors are promising energy storage devices due to their high power density and long cycle-life, which store the electrical energy at the electrode/electrolyte interface by means of reversible ion adsorption at high-surface-area porous carbon electrodes. Although supercapacitors have been significantly advanced by fabricating nanostructured materials, and developing thin-film manufacture technologies and device architectures, their energy densities are not comparable with those of lithium thin-film batteries. Compared to traditional supercapacitors based on the activated carbon material, the graphene supercapacitors show significantly advanced performance due to the larger surface area and higher ionic conductivity[1, 2]. On the other hand, the geometric design of the supercapacitors play a key role in determining the mean ionic path to decide the performance of the supercapacitors. It has been demonstrated that the interdigital supercapacitor design is advantageous over the traditional sandwich design due to the shortened mean ionic path[3]. In addition, the power and energy density increase as the width and the interspace of the electrodes decrease in the interdigital structure, which enlarge the lateral capacitance. Furthermore, the interdigital design can be ultrathin due to the removal of the additional separator layer. 

Here we demonstrate the fabrication of thin-film planar interdigital supercapacitors by using a high-spatial-resolution laser 3D printing technique, in which the porous graphene electrodes are produced by laser photo-reduction of graphene oxide. In this way, the interspace and the width of the electrodes are accurately controlled by the laser patterning at nanometer scale precision to shorten the mean ionic path and boost the lateral capacitance. The scanning electron microscopic image of the thin-film supercapacitor is shown Fig. 1. Through tuning the dimension of the patterned electrodes, the performance of the supercapacitor can be optimized, leading to high capacitance of 16 mF/cm2 exceeding the state-of-the-art laser fabricated graphene supercapacitor[3].