Untying the Bundles of Solution‐Synthesized Graphene Nanoribbons for Highly Capacitive Micro‐Supercapacitors

The precise bottom-up synthesis of graphene nanoribbons (GNRs) with controlled width and edge structures may compensate for graphene's limitations, such as the absence of an electronic bandgap. At the same time, GNRs maintain graphene's unique lattice structure in one dimension and provide more open-edge structures compared to graphene, thus allowing faster ion diffusion, which makes GNRs highly promising for energy storage systems. However, the current solution-synthesized GNRs suffer from severe aggregation due to the strong pi-pi interactions, which limits their potential applications. Thus, it is indispensable to develop a facile and scalable approach to exfoliate the GNRs from the postsynthetic aggregates, yielding individual nanoribbons. Here, a high-shear-mixing approach is demonstrated to untie the GNR bundles into practically individual GNRs, by introducing suitable molecular interactions. The micro-supercapacitor (MSC) electrode based on solution-processed GNR film exhibits an excellent volumetric capacitance of 355 F cm(-3) and a high power density of 550 W cm(-3), reaching the state-of-the-art performance of graphene and related carbon materials, and thus demonstrating the great potential of GNRs as electrode materials for future energy storage.