Graphene Nanofibers by Integrated Manufacturing of Electrospinning and Laser Graphitization for Miniaturized Energy Storage Devices

Carbon nanofibers (CNFs) are emerging as promising materials for miniaturized energy storage devices (MESDs) due to their high specific surface area, excellent electrochemical performance, low internal resistance, and durability. Their versatility and tunability make them ideal candidates for various applications, making CNFs a key player in advancing compact and efficient energy storage solutions. Nonetheless, CNFs necessitate an extra step involving either physical or chemical treatments to regulate their morphology, augment surface area, and create micropatterns suitable for MESDs. Here, innovations in material fabrication using an integrated manufacturing process are reported that combines electrospinning and laser-induced graphitization to create graphene nanofibers (GNFs) from fluorinated polyimide nanofibers (fPI NFs). Initially, electrospinning yields uniformly sized and shaped fluorinated poly(amic) acid nanofibers, which are subsequently thermally imidized to form fPI NFs. Laser photothermal treatment of fPI NFs generates hierarchical meso- and nanopores in GNFs, enhancing specific surface area and electrochemical properties, including specific capacitance, cyclic stability, rate capability, areal capacitance, power density, and energy density. This integrated approach synergistically fabricates GNFs for MESD applications, particularly GNF-based micro-supercapacitors (MSCs), demonstrating a remarkable areal capacitance and an aerial energy density two orders of magnitude higher than MSCs based on laser-induced graphene derived from conventional polyimide film.