Shearing induced ordered structures in two-dimensional nanomaterials-based electrodes for boosted pseudocapacitive kinetics

Two-dimensional (2D) nanomaterials have been extensively pursued as functional electrodes in electrochemical energy storage devices. Numerous efforts have been devoted to improving the electrochemical performance by engineering the chemical composition and structure of 2D nanomaterials, while little attention was paid to optimizing their electrode manufacturing by wet processing techniques. Herein, we study how the shear processing impacts the electrochemical performance of 2D nanomaterial-based electrodes using graphene oxide/polyaniline (GO/PANI) colloidal hydrogels as a model electrode slurry. The GO/PANI hydrogels are processed into reduced GO/PANI (RGO/PANI) membranes by blade casting followed by chemical reduction. The formation process and microstructure of the RGO/PANI membranes were revealed by rheology and synchrotron small-angle X-ray scattering. We find that a high shear rate in blade casting is favourable for inducing ordered alignment of the 2D nanosheet-like network structure of GO/PANI hydrogels, leading to the formation of stratified microstructure in the RGO/PANI membranes. The high shear-induced ordered structures greatly boost the pseudocapacitive kinetics of RGO/PANI membranes as flexible supercapacitor electrodes. Our findings highlight the significance of electrode processing of 2D nanomaterials for large-scale manufacturing for future industrial applications.