Graphene-based in-planar supercapacitors by a novel laser-scribing, in-situ reduction and transfer-printed method on flexible substrates

Planar integrated electrodes have recently attracted much attention owing to their unique and superior patterning design for portable and wearable energy storage devices. Most of previous in-plane micro-fabrications often involve complex processing which leads to high costs and delicate lithography protocols. In this work, a simple, novel and low-cost protocol for converting flexible and on-demand patterning into a coplanar symmetric supercapacitor is reported. The interdigitated architecture is readily fabricated by spontaneous deposition of reduced graphene oxide (rGO) on patterned conductive fabric templates and then electrodeposition of Ni metal. The obtained rGO/Ni pattern is then transfer-printed from the conductive fabric to a tape to form the interdigitated electrode with the bottom layer Ni serving as current collector and the top reduced graphene oxide layer for energy storage. The as-fabricated all-solid-state planar symmetric supercapacitors exhibit a much lower contact resistance, higher capacitances and better rate-capabilities. It acquires a maximal areal capacitance of 12.5 mF cm⁻² at a scan rate of 5 mV/s, exhibiting an energy density of 2.25 mW h cm⁻³ at a power density of 0.04 W cm⁻³, and can maintain 94.8% of its initial capacitance after 20,000 cycles.