A flexible graphene/polyaniline hybrid material as a supercapacitor electrode was synthesized by an in situ polymerization-reduction/dedoping-redoping process. This product was first prepared in an ethylene glycol medium, then treated with hot sodium hydroxide solution to obtain the reduced graphene oxide/polyaniline hybrid material. Sodium hydroxide also acted as a dedoping reagent for polyaniline in the composite. After redoping in an acidic solution, the thin, uniform and flexible conducting graphene/polyaniline product was obtained with unchanged morphology. The chemical structure of the materials was characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. The composite material showed better electrochemical performances than the pure individual components. A high specific capacitance of 1126 F g⁻¹ was obtained with a retention life of 84% after 1000 cycles for supercapacitors. The energy density and power density were also better than those of pure component materials.

Well-designed nanostructures of a ternary nanocomposite, graphene/Fe₂O₃/polyaniline, are fabricated via a two-step approach. Graphene oxide is reduced by Fe²⁺ and well-dispersed by loading α-Fe₂O₃ nanoparticles (20–70 nm in size). A thin film of polyaniline is in situ polymerized on the graphene/Fe₂O₃ surfaces for the fabrication of its ternary composite. Among the composites obtained at different ratios of graphene/Fe₂O₃ to polyaniline, the ternary graphene/Fe₂O₃/polyaniline with a ratio of 2 : 1 exhibits a high specific capacitance of 638 F g⁻¹ in 1 M KOH at a scan rate of 1 mV s⁻¹ and experiences only a negligible decay of 8% after 5000 cycles. It also shows a higher energy density at high power density than other ternary or binary composites of the three components, respectively. The extraordinary electrochemical performance of the composite arises from the well-designed structural advantages of the ternary nanocomposite, and the good combination and synergistic effects among the three components. Graphene sheets, as the conducting frameworks for sustaining polyaniline and Fe₂O₃, can separate and disperse well in the composite due to the existence of Fe₂O₃. On the other hand, the thin film of polyaniline on the surface of graphene/Fe₂O₃ not only enhances the surface area, but also restricts the dissolution, aggregation and volume changes of Fe₂O₃ during charge–discharge cycling. Additionally, the existence of Fe₂O₃ is helpful to increase the rate stability of the ternary composite. The ternary composites with synergistic effects can take advantage of both Faradaic and non-Faradaic processes for capacity-charge storage with excellent electrochemical properties.

The specific capacity and cycling performance of the hierarchical electrode were significantly enhanced due to the sulfur doping into Co ₃ O ₄ .

A ternary electrode material, based on graphene, tin oxide (SnO₂) and polypyrrole (PPy) was obtained via one–pot synthesis. The graphene/SnO₂/PPy (GSP) nanocomposite is composed of a thin conducting film of PPy on the surface of graphene/SnO₂ (GS). An enhanced specific capacitance (616 F g⁻¹) of GSP was obtained at 1 mV s⁻¹ in 1 M H₂SO₄ compared with GS (80.2 F g⁻¹) and PPy (523 F g⁻¹). The GSP electrode shows better cycle stability and no obvious decay after 1000 galvanostatic cycles at 1 A g⁻¹. Its specific power density and energy density can reach 9973.26 W kg⁻¹, and 19.4 W h kg⁻¹, respectively. The excellent electrochemical performance arises from the well-designed structure advantages, the good combination of components and the synergistic effect between the three components. Well-dispersed graphene is used as a framework for sustaining the pseudocapacitive materials of SnO₂ and PPy. The PPy film restricts the aggregation and volume change of SnO₂ during charge–discharge cycling, and also enhances the surface area. The electrochemical results show that the ternary composite of GSP is a promising candidate electrode material for high-performance supercapacitors.

Reduced-graphene oxide/molybdenum oxide/polyaniline ternary composites, RGO(MP), for use as electrode materials for high energy density supercapacitors, were firstly synthesized using a one-step method with Mo₃O₁₀(C₆H₈N)₂·2H₂O and graphene oxide (GO) as precursors. When the mass ratio of Mo₃O₁₀(C₆H₈N)₂·2H₂O to GO is 8 : 1, the resulting composite RGO(MP)₈ shows excellent electrochemical performance with a maximum specific capacitance of 553 F g⁻¹ in 1M H₂SO₄ and 363 F g⁻¹ in 1 M Na₂SO₄ at a scan rate of 1 mV s⁻¹. Its energy density reaches 76.8 W h kg⁻¹ at a power density of 276.3 W kg⁻¹, and 28.6 W h kg⁻¹ at a high power density of 10294.3 W kg⁻¹ in H₂SO₄. While in Na₂SO₄, the energy density achieves 72.6 W h Kg⁻¹ at a power density of 217.7 W kg⁻¹ and 13.3 W h Kg⁻¹ at power density of 3993.8 W kg⁻¹, respectively. The composite also presents good cycling stability (86.6, 73.4% at 20 mV s⁻¹ after 200 cycles in 1 M H₂SO₄ and Na₂SO₄, respectively).