Improved Ion‐Transfer Behavior and Capacitive Energy Storage Characteristics of SnO2 Nanospacer‐Incorporated Reduced Graphene Oxide Electrodes

This report demonstrates the modification of reduced graphene oxide (RGO) nanosheets by decorating SnO2 nanorod bundles and nanoparticles on the surface for effective use of the graphene as supercapacitor electrode materials. The shape‐ and density‐controlled SnO2 nanostructures were prepared through hydrothermal synthesis and acted as spacer materials to physically inhibit the overlapping of the RGO sheets; this is known as the restacking effect. When measuring the electrochemical properties, the electrode comprising RGO with SnO2 nanorod bundles (RGO−SnO2−NR) revealed a higher capacitance, rate capability, and cyclic stability than the RGO electrode with SnO2 nanoparticles (RGO−SnO2−NP) and the bare RGO electrode, indicating the effective role of the surface‐implanted SnO2 spacer during the electrode reactions of the double‐layer capacitor. The electrochemical superiority of RGO−SnO2−NR could be explained by the fact that wedge‐like SnO2 nanorod bundles between the RGO sheets promote fast transfer and approach of electroactive species to form the electrochemical double layer at the electrode surface. Moreover, the improved mass transfer behavior of the RGO−SnO2 composite electrodes and the role of the SnO2 nanostructures were reasonably verified by various electrochemical analyses. Plant the seed: The electrochemical performance of RGO−SnO2 composite electrodes that show double‐layer capacitive characteristics varies depending on the morphology of the surface‐implanted SnO2 nanospacer. The electrode with RGO−SnO2 nanorod bundles gives the highest specific capacitance as well as the best rate performance and cyclability, which can be attributed to facilitated accessibility of the ions during the surface reactions.