Direct laser writing of MnOx decorated laser-induced graphene on paper for sustainable microsupercapacitor fabrication

Laser-induced graphene (LIG) on paper is a popular choice for fabricating flexible micro-supercapacitors (MSCs) as it is a simple and sustainable process. However, carbon-based MSC electrodes have limited energy densities. To address this challenge, this study presents a highly reproducible and cost-effective method for decorating manganese oxide (MnOx) on interdigital LIG MSC electrodes, fabricated via a single-step direct laser writing (DLW) process on paper substrates. The paper fibers embedded with MnOx precursors are transformed into graphene through laser processing while reducing the salt, resulting in the formation of MnOx-LIG. The resulting MnOx-LIG-MSC exhibits a specific capacitance of 12.30 mF cm−2 (0.05 mA cm−2) with a 60 % retention at 1000 bending cycles (30°), due to the pseudocapacitive contribution of MnOx. Furthermore, the devices exhibit high electrochemical stability, retaining 190 % of the initial specific capacitance after 10,000 cycles, and a high energy density of 2.6 μWh cm−2 (at a power of 0.109 mW cm−2). The study demonstrates that manganese oxide-based LIG-MSCs have the potential to be used as energy storage devices for portable, low-cost, and flexible paper electronics.