Interfacial Engineering of Reduced Graphene Oxide for Aramid Nanofiber‐Enabled Structural Supercapacitors

Abstract Structural energy storage systems can simultaneously store energy and bear mechanical loads and are emerging technologies for electric vehicles, aircrafts, and satellites since they offer significant mass and volume savings. However, many of the materials used in energy storage applications are not mechanically robust or, on the other hand, mechanically stiff materials are not necessarily electrochemically active. One solution is to combine reduced graphene oxide (rGO) sheets and aramid nanofibers (ANFs). Here we hypothesize that engineering the interfacial interactions between rGO sheets and the ANFs will lead to enhanced mechanical properties, as noncovalent interactions offer multiple sites for load transfer. rGO sheets are functionalized with carboxylic acid (−COOH) and amine (−NH₂) groups, and the effect on the mechanical and electrochemical performance of nanocomposite supercapacitor electrodes is investigated. Notably, the −NH₂ functionalization and the addition of ANFs leads to a dramatic 200 % improvement of the strength of the electrodes without significantly compromising the electrochemical performance. Furthermore, it is demonstrated that these electrodes’ multifunctionality is superior to other state‐of‐the‐art structural electrodes and may pose possible replacements for steel or epoxy. These findings provide critical knowledge for the design of next‐generation multifunctional electrodes in that we highlight the importance of interfacial engineering.