Fully Printed and Encapsulated Flexible Micro‐Supercapacitors Based on Activated Carbon and Conducting Polymer Composite

The integration of flexible micro‐supercapacitors (m‐SCs) with wearable electronics requires reliable device protection to improve durability under practical operating conditions. However, achieving scalability and sustainability in flexible m‐SCs remains challenging, highlighting the need for simple, low‐cost fabrication methods and sustainable functional materials. Here, we demonstrate the direct ink writing of activated carbon‐based flexible m‐SCs with a printed encapsulation layer. The activated carbon ink uses water as the primary solvent and poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a conductive binder, eliminating the need for additional conductive elements and fluorinated binders typically used in activated carbon‐based SCs. To facilitate scalable fabrication, the complete m‐SC is fabricated using direct ink writing (DIW), including the printing of the electrodes, orthophosphoric acid‐based gel electrolyte, and PDMS encapsulation. The final fabricated device exhibits a specific areal capacitance of 78 mF/cm ² at a scan rate of 5 mV/s. The PDMS layer protects the electrodes from environmental factors, preventing electrolyte leakage and drying, enabling 10 000 cycles with 95% capacitance retention and extending the device’s overall lifespan. Thus, fully printed m‐SCs are demonstrated using a single technique, namely DIW, thereby ensuring easy, scalable production. The printed m‐SCs are lightweight, flexible, and sustainable with high cyclic stability.