Challenges in carbon ink formulation and strategies for fabrication of flexible supercapacitors

The growing demand for flexible electronics has highlighted the significance of carbon-based conductive inks due to their cost-effectiveness, processability, conductivity, biocompatibility, and flexibility. This review investigates advanced materials such as graphene, carbon nanotubes, carbon black, and activated carbon, which are pivotal for ink formulation. It examines transformative printing technologies, including screen printing, inkjet printing, spray printing, direct ink writing, flexo-printing, and 3D printing. Advancements in ink formulations are discussed with a focus on the roles of binders, resins, and solvents, alongside challenges like optimizing rheological properties, particle sizes, and substrate adhesion. Each printing method's advantages and limitations are analysed concerning ink parameters like viscosity, stability, and compatibility with flexible substrates. By addressing the challenges and potential of carbon-based ink formulation, this review seeks to drive innovation in printed flexible electronics and energy storage devices for modern portable technologies.