N, B, and S heteroatom-doped laser-induced porous PES-derived graphene for high-performance supercapacitors

Abstract

Laser-induced graphene (LIG) has emerged as a highly promising electrode material for energy storage applications owing to its unique advantages. However, the experimental capacitance of pristine LIG electrodes remains significantly lower than their theoretical limit, primarily due to limited active sites and insufficient charge carrier density. To address this challenge, the incorporation of heteroatoms into the graphene lattice can generate additional charge carriers, improving the electrical conductivity and overall properties. This leads to a significant enhancement in the electrochemical performance of laser-induced graphene (LIG) composites. In this study, we report a simple yet efficient laser-direct writing approach for the fabrication of N, B, and S tri-doped LIG (NBS-LIG) composite electrodes. The NBS-LIG electrodes were prepared through repeated laser scribing on a pre-fabricated B-doped S-LIG film with the same laser parameters. This synergistic multi-heteroatom co-doping not only induces structural defects that serve as electrochemically active sites but also enhances ion diffusion kinetics and electron-transfer capability. The resulting NBS-LIG electrode exhibits an outstanding areal specific capacitance of 240 mF cm⁻² at the current density of 0.5 mA cm⁻². The areal specific capacitance of the NBS-LIG electrode is maintained at 79.2% of its original value, as the current density is increased 20-fold to 10 mA cm⁻². Furthermore, the fabricated symmetric supercapacitor (SC) based on NBS-LIG delivers a high C_A (29 mF cm⁻²) at 0.4 mA cm⁻² and a high areal energy density of 4.03 µWh cm⁻² at an areal power density of 200 µW cm⁻². This study establishes a completely novel method for N, B and S co-doped LIG, which introduces N, B and S atoms into LIG to enhance the performance of supercapacitors and offers different insights into the synthesis of multi-atom co-doped LIG.