Development of 3D MoO3/graphene aerogel and sandwich-type polyaniline decorated porous MnO2−graphene hybrid film based high performance all-solid-state asymmetric supercapacitors

Highlights: • A novel 3D MoO₃/graphene aerogel was synthesized using hydrothermal method. • A 3D porous sandwich-type polyaniline/graphene-MnO₂/polyaniline hybrid film was developed. • The all-solid-state asymmetric supercapacitor showed excellent electrochemical properties. A new flexible all-solid-state asymmetric supercapacitor with very high energy density has been fabricated by adopting a 3D heterogeneous composite based on polyaniline (PANI) and graphene and enlarging its operating voltage window. This novel supercapacitor is based on the 3D molybdenum oxide/graphene aerogel (MoO₃/GF) composite as the negative electrode and the sandwich-type PANI decorated 3D porous manganese dioxide/reduced graphene oxide hybrid film (PANI/(MnO₂−RGO)/PANI) as the positive electrode material. Polyvinyl alcohol/potassium hydroxide (PVA/KOH) was used as the gel electrolyte. The self-assembled 3D MoO₃/GF was synthesized by hydrothermal route followed by heat treatment in a furnace. For the positive electrode, a facile novel 3D MnO₂−RGO porous film was first fabricated by vacuum filtration of MnO₂ and GO suspension, followed by hydrothermal chemical reduction. Then, PANI nanofibers were grown on top of the hybrid film. The fabrication steps show a facile formation of the 3D sandwich-type PANI/(MnO₂−RGO)/PANI porous hybrid film. The asymmetric supercapacitor (MoO₃/GF//PANI/(MnO₂−RGO)/PANI) showed a high energy density of 51.91 Wh kg⁻¹ at a power density of 0.838 kW kg⁻¹. The asymmetric cells were flexible, and three cells connected in series could illuminate a green-LED for 62 s.