Versatile Conductive Ink Formulation for Enhanced Electrochemical Performance in Flexible Printed Micro-supercapacitors Using SnO₂/rGO Nanocomposites

The rise of flexible and wearable electronics has spurred advancements in printed, flexible micro-supercapacitors for energy storage. This study presents the fabrication of flexible micro-supercapacitors using a novel nanocomposite of tin dioxide grown on layered reduced graphene oxide through one-pot in situ synthesis. The conductive functional ink, formulated by mixing the nanocomposite, is effectively utilized in screen-printing technology. The resulting micro-supercapacitors, particularly the SG-1 variant, demonstrate impressive electrochemical performance. The nanocomposites show exceptional versatility across various electrolytes, including alkaline, acidic, and quasi-gel electrolytes with a polyvinyl alcohol matrix infused with potassium hydroxide. An in-depth comparison of their efficacy in these electrolytes highlights the most suitable configurations for optimal performance. At a scan rate of 5 mV s⁻¹, SG-1 achieves areal capacitances of 148.7 mF cm⁻² and 87.7 mF cm⁻² in the 1 M KOH and polyvinyl alcohol infused with 1 M KOH quasi-gel electrolyte. Additionally, SG-1 in the gel electrolyte demonstrates remarkable energy density of 11.7 mWh cm⁻² at power density of 490 mW cm⁻². Notably, the fabricated micro-supercapacitors exhibit excellent capacitive retention of 89.5% even after undergoing 5000 cycles of charge–discharge, underscoring their robustness and long-term stability for practical applications in flexible and wearable electronics.