Poly(3,4-ethylenedioxithiophene) coated on vanadium oxide hydration nanobelts enhancing ammonium-ion storage for hybrid supercapacitors.

The development of electrode materials for aqueous ammonium-ion supercapacitors (NH-SCs) has garnered significant attention in recent years. Poor intrinsic conductivity, sluggish electron transfer and ion diffusion kinetics, as well as structural degradation of vanadium oxides during the electrochemical process, pose significant challenges for their efficient ammonium-ion storage. In this work, to address the above issues, the core-shell VO·nHO@poly(3,4-ethylenedioxithiophene) composite (denoted as VOH@PEDOT) is designed and prepared by a simple agitation method to boost the ammonium-ion storage of VO·nHO (VOH). The 3,4-ethylenedioxithiophene (EDOT) monomer polymerizes on the VOH surface to form a polymer shell resulting in the formation of VOH@PEDOT core-shell structure, and also introduces oxygen vacancies. The conductive PEDOT coating enhances the conductivity of VOH, facilitates electron transfer and transport capabilities, as well as relieves the structural degradation of VOH. As expected, with the breaking/formation of hydrogen bond between NH and V-O layers, VOH@PEDOT exhibits more efficiently reversible (de)intercalation of NH, thus having a high specific capacitance of 409F·g at 0.5 A·g and improve cyclic stability in NHCl/PVA electrolyte. The study demonstrates that the conducting polymer can enhance the electrochemical performance of vanadium oxides for NH-SCs, offering new insights for designing and developing vanadium oxide electrode materials for high-efficient NH storage.