Revealing Pseudocapacitive Mechanisms of Metal Dichalcogenide SnS2/Graphene‐CNT Aerogels for High‐Energy Na Hybrid Capacitors

Abstract SnS 2 nanoplatelet electrodes can offer an exceptionally high pseudocapacitance in an organic Na + ion electrolyte system, but their underlying mechanisms are still largely unexplored, hindering the practical applications of pseudocapacitive SnS 2 anodes in Na‐ion batteries (SIBs) and Na hybrid capacitors (SHCs). Herein, SnS 2 nanoplatelets are grown directly on SnO 2 /C composites to synthesize SnS 2 /graphene‐carbon nanotube aerogel (SnS 2 /GCA) by pressurized sulfidation where the original morphology of carbon framework is preserved. The composite electrode possessing a large surface area delivers a remarkable specific capacity of 600.3 mA h g −1 at 0.2 A g −1 and 304.8 mA h g −1 at an ultrahigh current density of 10 A g −1 in SIBs. SHCs comprising a SnS 2 /GCA composite anode and an activated carbon cathode present exceptional energy densities of 108.3 and 26.9 W h kg −1 at power densities of 130 and 6053 W kg −1 , respectively. The in situ transmission electron microscopy and the density functional theory calculations reveal that the excellent pseudocapacitance originates from the combination of Na adsorption on the surface/Sn edge of SnS 2 nanoplatelets and ultrafast Na + ion intercalation into the SnS 2 layers.