3D printable graphite-silicone ink and direct ink writing for electrochemical applications

3D-printing is revolutionizing electrochemical laboratories, with techniques like direct ink writing (DIW) remaining underexplored, mainly due to the lack of printable materials that meet electrochemical standards. In this work, we developed a low-cost, easily formable conductive ink, composed of graphite (conductive phase), silicone (binder), and chloroform (viscosity modulator). A 3:2 graphite-to-silicone ratio provided a balance between printability and electrochemical performance. The utility of graphite-silicone-based platforms was tested in electroanalytical and energy storage applications. We challenged DIW to manufacture elastic and entirely 3D-printed electrochemical cell. Besides, these were integrated into FDM-printed housings and tested for cocaine sensing. We also found that a simple electrochemical pre-treatment (application of a cathodic potential) significantly enhanced the capacitance of printed electrodes, from a few to several thousand µF·cm−2. Finally, graphite-silicone 3D-printed electrodes were employed as anode in Li-ion batteries. Despite large mass and volume, these electrodes after formation process achieved discharge capacity of ~120 mAh·g−1 (~10 mAh·cm−2) at C/40 rate with near 100% Coulombic efficiency. The ink formulation is low-cost (€2 per 100 g), straightforward, and offers the notable advantage of real-time tunability — an improvement over commonly used carbon-based thermoplastic filaments.