In-situ Joule Heating-Triggered Nanopores Generation in Laser-Induced Graphene Papers for Capacitive Enhancement

Abstract Laser-induced graphene (LIG) technology featured with low-cost, high-efficiency and scalable has presented great advantage in micro-supercapacitors (MSCs) fabrication. However, the limited capacitance of LIG based MSCs is still hindering their further development. Herein, we introduce joule heating as a critical in-situ treatment merged with the assembly of laser-induced graphene paper based MSCs (LIGP-MSCs) toward capacitive enhancement. By increasing heating-treatment temperature from ∼20 to 500 °C, the increasing nanopores can be formed in LIGP attributed to the gradual decomposition of amorphous carbon components. The resulting joule-heated LIGP (J-LIGP) with improved specific surface area (160.97 - 533.49 m2/g) and pore volume (0.179 - 0.553 cm3/g) as well as superhydrophilic surface is highly suitable to be employed as J-LIGP-MSCs microelectrodes. The J-LIGP-MSCs heated at 500 °C for 60 minutes delivers a significantly improved specific areal capacitance (CA) of 13.71 mF/cm2 at 10 mV/s, which is approximately six-fold that of unheated LIGP-MSCs. It only takes 5 minutes for J-LIGP-MSCs heated at 550 °C to achieve a CA of 12.61 mF/cm2. Superior mechanical flexibility, cyclability and modularity of J-LIGP-MSCs are also achieved. Furthermore, in-situ joule heating treatment is demonstrated to be a general approach for enhancing the capacitive performance of LIG based MSCs.