Free-standing Ni–Fe-doped laser-induced-graphene as binder-free electrodes for high-areal-capacitance symmetric microsupercapacitor

Laser-induced graphene (LIG) has garnered significant attention for its cost-effectiveness and high efficiency in fabricating flexible micro-energy storage devices. For the sake of enhancing the electrochemical performance of graphene electrodes, transition metal-doped graphene is a feasible strategy. Carbon cloth (CC) has good electrical conductivity, and polyethersulfone (PES) is a kind of polymer containing sulfur. In this study, Ni–Fe/CC@PES-LIG electrode materials have been prepared successfully via scribing the Ni–Fe/CC@PES films under CO₂ atmosphere by laser direct writing technology. The addition of carbon cloth not only improves the electric conductivity of as-prepared samples, but also provides a self-supporting fluid collector, and the synergistic effect with the transition metal greatly improves the electrochemical performance of the electrodes. An integrated Ni–Fe/CC@PES-LIG-10W electrode material exhibited high areal specific capacitance of 580 mF cm⁻² at 1 mA cm⁻², which enhanced about 20 times approximately after carbon cloth acted as current collect. Symmetric microsupercapacitors (SMSCs) were established using two identical integrated Ni–Fe/CC@PES-LIG electrodes because they can work in both the positive and negative potential windows. The fabricated SMSCs showed a wide potential window of 1.7 V and high areal specific capacitance of 95 mF cm⁻² at 1 mA cm⁻² with 93% specific capacitance retention after 6000 cycles. This study provides a simple and effective strategy for the further application of the laser direct writing technology in the field of electronic products.