Fast synthesis of LIG–PEEU supercapacitors using femtosecond laser-assisted liquid-phase environmental simulation

• Proposed a femtosecond laser-assisted liquid-phase environmental simulation processing technique for rapid laser-induced graphene–polyether ether urea (LIG–PEEU) composite synthesis. • Integrated LIG to boost PEEU’s electrical and electrochemical performance. • Used femtosecond lasers for precise, low-cost material synthesis. • Achieved high capacitance, energy density, and stability in LIG–PEEU-based micro-supercapacitors. • Simplifies PEEU synthesis and offers potential for flexible supercapacitors. This work presents an innovative method of synthesizing laser-induced graphene–polyether ether urea (LIG–PEEU) composites using femtosecond laser-assisted liquid-phase processing. By the creation of a high-temperature, high-pressure, oxygen-free environment in ethanol, the laser enabled rapid PEEU polymerization on PI films and simultaneous graphene formation. This approach circumvents the challenges of long time, harsh conditions, difficult application associated with conventional PEEU synthesis and enhances the electrical properties of the material by the integration of LIG. The unique porous structure of the LIG and the polar groups of the PEEU optimized the electrochemical performance of the composite. Optimal conditions (which included a laser of 200 kHz, an energy of 0.9 µJ, a speed of 2 mm/s, a line spacing of 0.05 mm, and a 2:1 precursor mass ratio) produced an LIG–PEEU composite with excellent capacitance (84 mF/cm 2 ). Micro-supercapacitors fabricated from this composite exhibited excellent stability, flexibility, and performance, thereby opening new avenues for high-performance micro-supercapacitors and flexible energy storage technologies.