Boron and fluorine Co-doped laser-induced graphene towards high-performance micro-supercapacitors

Laser-induced graphene (LIG) has attracted extensive research as an electrode material for micro-supercapacitors (MSC). However, the low capacitive performance of LIG arising from both limited specific surface area and few active sites remains challenging. Herein, in situ doping of fluorine and boron atoms into laser-induced graphene was innovatively achieved via laser direct writing approach using boron-doped fluorinated polyimide (FB-PI) as the precursor. The porous fluorine and boron co-doped laser-induced graphene (FB-LIG) exhibits more active sites and improved wettability and significantly enhanced capacitive performance due to the synergistic effect of fluorine and boron co-doping. By tuning the weight ratio of boron to fluorine, the MSC utilizing FB-LIG as the electrode and poly(vinyl alcohol) (PVA)/H2SO4 as the gel electrolyte delivers a high areal capacitance of 49.81 mF/cm2 at a current density of 0.09 mA/cm2, 23 times higher that of MSC from commercial polyimide (PI)-based LIG, and 3 times that of MSC from fluorinated PI-based LIG. In addition, MSCs from FB-LIG possess excellent mechanical stability and flexibility, rendering them promising for flexible wearable microelectronics.