Laser-induced graphene supercapacitors on flex substrates for package-integrated power supply

Abstract

Integrated power sources have a critical role in the operation of miniaturized, lightweight, wearable medical and IoT devices. Such power sources should be ideally grown directly on the package substrates for low-impedance power delivery and assembled in planar architectures while also achieving higher power densities. This paper shows laser-induced graphene supercapacitors on flexible packages to address that critical need. With the proper selection of laser wavelength and power, polyimide can be selectively transformed into porous graphene to form high surface area electrodes. These graphene layers are integrated with copper tape to a stainless-steel substrate to form planar supercapacitor layers. Initial testing was performed with liquid electrolytes. Capacitance densities of 1.2 mF/cm2, comparable to current porous graphene capacitors but with a simpler process, was thus achieved. This unique nanomanufacturing paradigm can broadly benefit all future power module integration strategies.