Eco-Friendly Energy Storage and Energy Harvesting Devices Fabricated by Direct Laser Writing of Chitosan-Lignin-Boric Acid Substrates

Eco-friendly supercapacitor (SC) and triboelectric nanogenerator (TENG) devices were assembled using laser-induced graphene (LIG) electrodes fabricated by direct laser writing of chitosan-lignin-boric acid films. A simple one-step laser irradiation was used to convert the chitosan-based films into 3D, interlinked, and electrically conductive LIG electrode materials. Assembled SCs displayed specific areal capacitances up to 21.4 mF/cm² at a current density of 0.05 mA/cm² and 68% capacitance retention for >10,000 charge/discharge cycles. When charged by a commercial solar cell, the SC could power a digital thermo-hygrometer, an electronic stopwatch and a calculator, showing potential for real applications. Single-electrode TENG (SE-TENG) devices were also assembled using PDMS as the dielectric layer. The TENGs displayed an open-circuit voltage of 13.3 V, a short-circuit current of 1.7 μA, and stability over 10,000 cycles. The TENG could charge commercial SCs of 0.1 and 1 μF capacitance in less than 60 s. This work demonstrates the suitability of sustainable materials as feedstock constituents for the generation of LIG electrodes and opens the door to the large-scale production of cost-effective electrode materials for “green” wearable electronic applications.