Laser Scribing of Fluorinated Polyimide Films to Generate Microporous Structures for High-Performance Micro-supercapacitor Electrodes

Laser-induced graphene (LIG) typically exhibits a mesostructure with a small specific surface area, which is detrimental to the electrochemical performance of micro-supercapacitors (MSCs). Herein, 3D nanostructured LIGs patterned on fluorinated polyimides (fPIs) via a laser photothermal method are reported. During laser-induced graphitization, a highly microporous structure in the LIG develops. Consequently, the patterned LIG (LIG-fPI) exhibits a very large specific surface area (1126.0 m2 g-1), thereby enhancing its electrochemical performance. Specifically, in an H2SO4 aqueous electrolyte, the micropatterned electrode exhibits an exceptional areal capacitance of 110 mF cm-2 (determined by cyclic voltammetry), which is 27 times higher than that of a LIG based on commercial polyimides and at least 7 times higher than that of current state-of-the-art MSCs. Furthermore, mechanically stable and flexible LIG-fPI-MSCs with an organic gel polymer electrolyte (working potential = ∼3 V) show very high power and energy densities of 0.58 mW cm-2 and 0.01 mW h cm-2, respectively. Thus, these LIGs are promising for application in high-performance MSCs for flexible microelectronics.