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 (MnO_x) on interdigital LIG MSC electrodes, fabricated via a single-step direct laser writing (DLW) process on paper substrates. The paper fibers embedded with MnO_x precursors are transformed into graphene through laser processing while reducing the salt, resulting in the formation of MnO_x-LIG. The resulting MnO_x-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 MnO_x. 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.