Direct ink writing-based 3D printing of supercapacitors for flexible and wearable electronic applications

Abstract

Direct ink writing-based 3D printing is one of the most effective methods for sustainable manufacturing of flexible and wearable electronic devices. It is gaining wide attention for soft and wearable electronics fabrication due to its several attributes like its ability to process a wide range of materials, flexible form factors, high scalability, reduced material waste, and capability to produce complex intricate structures. Here, we report a solid-state, asymmetric, and flexible supercapacitor fabricated using Direct ink writing (DIW) technology. Numerical simulation was used to optimize the printing parameters, and the simulation results were in good agreement with the experimental results. The rheology of the inks was also optimized for better printability. Inks for the positive and negative electrodes of the supercapacitors were prepared by mixing silicone with a graphene-carbon nanotube composite and MnO₂, respectively. The 3D-printed supercapacitors exhibited outstanding electrochemical performance within a voltage range of 0 to 1.8 V using a poly(vinyl alcohol)-LiCl gel electrolyte. The developed device demonstrated high flexibility, reliable cycle life performance, impressive rate capability, and a high energy density. It achieved a maximum specific capacitance of 92.72 mF cm⁻² at a current density of 2 mA cm⁻², maximum energy density of 0.041 mWh cm⁻² at a power density of 1.8 mW cm⁻², and capacity retention of 89.78% even after prolonged use. This work demonstrates the high potential of the DIW method for the sustainable fabrication of supercapacitors and other electronics for next-generation flexible and wearable devices.