Paper-Based Solid-State Micro-supercapacitors Fabricated by Hydrophobic Wax Barrier Printing

Flexible and small-scale energy storage technologies are critical for future applications such as wearable electronics. In this context, paper has emerged as a lightweight, low-cost, and ecologically friendly flexible substrate for energy storage devices. This paper presents a simple method for fabricating a micro-supercapacitor (MSC) using a wax printing approach that can achieve high resolution without requiring complex processes. In addition, the developed MnO₂–Au-paper (MAP) microelectrodes with high porosity exhibit enhanced charge and ion transfer while maintaining a stable flexibility. The solid-state micro-supercapacitor delivers a very large areal capacitance of 624.32 mF cm⁻² at 0.2 mA cm⁻² and is stable under external stress. The highest energy and power densities obtained for the present MSCs (55.5 μWh cm⁻² and 1.59 mW cm⁻², respectively), are much larger than those previously reported for pseudocapacitive MSCs, including flexible ones.