Nitrogen and phosphorous Co-Doped Laser-Induced Graphene: A High-Performance electrode material for supercapacitor applications

[Display omitted] •N and P co-doped LIG is prepared based on duplicated laser pyrolysis method.•P-dopant precursor and second laser power effects on LIG are investigated.•NP-LIG shows favorable surface chemistry for capacitive performance.•NP-LIG shows remarkably higher CA (69.7 mF/cm2) compared with N-LIG and s-LIG. A versatile and cost-effective strategy is demonstrated to produce N and P co-doped laser-induced graphene (NP-LIG) based on a duplicate laser pyrolysis method. The dopant precursor concentration and laser power significantly affected the surface chemistry and electrochemical performance of the NP-LIG. The NP-LIG optimized with 3 wt% H3PO4 and laser power of 3.5 W (NP3-LIG-3.5) in the second pyrolysis step demonstrated an impressive specific areal capacitance (CA) of 163.6 mF/cm2 at 0.2 mA/cm2 in a three-electrode system where 1 M H2SO4 was used as an aqueous electrolyte. Furthermore, the solid-state NP3-LIG-3.5 supercapacitor (NP3-LIG-SC) assembled with a gel electrolyte (PVA-H2SO4) showed a high CA of 69.7 mF/cm2 at 0.05 mA/cm2, which is 4 and 13 times higher, respectively, than those of N-doped LIG and singly pyrolyzed LIG SCs. In addition, the NP3-LIG-SC exhibited good cycling stability (capacitance retention of 84% after 10,000 cycles), a Coulombic efficiency of approximately 100%, and a high areal energy density of 9.67 µWh/cm2. This study proposes a facile method for the fabrication of heteroatom-co-doped LIG electrodes for use in flexible and wearable electronics.