Bio-inspired 3D-Printed supercapacitors for sustainable energy storage

This study presents a significant enhancement of the electrochemical properties of commercially available high-surface-area bare activated carbon (BAC) through the grafting of catechin hydrate (CH) redox active molecules. The grafting of CH onto the BAC was confirmed by the results from the Thermogravimetric analysis, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller. Moreover, this study introduces 3D printed deep eutectic solvent electrolytes, composed of choline chloride and urea, highlighting the potential of sustainable and greener materials in energy storage. A 3D-printed fully bio-inspired supercapacitor achieved a maximum specific capacitance of 75 F g⁻¹ at a scan rate of 1 mV s⁻¹ (37 F g⁻¹ at a current density of 0.2 A g⁻¹), demonstrating performance comparable to that of previously reported state-of-the-art fully 3D-printed and disposable paper supercapacitors (25.6 F g⁻¹ at a scan rate of 1 mV s⁻¹ for 1.2 V). Furthermore, the device exhibited electrochemical performance within an extended potential window of 2.0 V, coupled with cycling stability of approximately 90.2 % after 10,000 cycles, offering a specific energy of 20.6 W h kg⁻¹ at a specific power of 560 W kg⁻¹. The developed bio-inspired, eco-friendly, sustainable, 3D-printed supercapacitors can replace the harmful Li-ion batteries currently used in low-power wireless sensor applications.