Search

• Graphene/PANI/MnO 2 composites are fabricated by facile two-step electrodeposition. • Graphene hydrogel films act as working electrodes for sequential electrodeposition. • The ternary composite electrode exhibits excellent capacitive performance. • The symmetric device performs well in rate capacity, stability and energy density. The incorporation of various capacitive materials to fabricate multi-component electrodes has emerged as a feasible methodology toward high-performance supercapacitors. In this paper, a facile two-step electrodeposition method is proposed to construct polyaniline (PANI)/MnO 2 hybrid nanostructure on reduced graphene oxide (RGO) matrix for the ternary supercapacitor electrodes. By the sequential potentiostatic methods, PANI is first electropolymerized on RGO hydrogel films before MnO 2 granules are electrodeposited on the RGO/PANI conductive substrates to obtain the free-standing composite films. The resulting RGO/PANI/MnO 2 ternary composite electrodes present significantly promoted capacitive properties compared with the binary RGO/PANI electrodes. Particularly, the optimized electrode and corresponding all-solid-state device could achieve the high specific capacitances of 942.6 and 205.0 F g–1 at 1 A g–1 with superb capacitance retention of 86.4% and 80.3% at 30 A g–1, respectively. The device delivers a maximum energy density of 41.0 Wh kg–1 and demonstrates outstanding capacitance holdings of 96.1% after 10,000 cycles at 30 A g−1, 87.8% after 5000 cycles at 10 A g−1, and 82.5% after 3000 cycles at 5 A g−1, respectively. The prominent electrochemical performances of the ternary composite can be ascribed to the fact that graphene supplies the conductive matrix to immobilize the active pseudocapacitive constituents, while PANI and MnO 2 can compensate each other to surmount the disadvantages of inferior conductivity or stability. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The hydrated GO/PANI film fixed on carbon cloth is achieved via water evaporation. • Integrated rGO/PANI/CC electrode is obtained by facile hydrazine reduction. • High rGO/PANI mass loading is realized via repeating dropping/evaporating process. • The integrated electrode displays excellent capacitance and rate performance. • The all-solid-state device exhibits high energy density toward promising potentials. The convenient fabrication of supercapacitor electrodes with high active material mass loading is of great significance to the practical application. In this paper, a novel and efficient strategy is proposed to prepare graphene/polyaniline (PANI) composite with controllable mass loading towards high-performance supercapacitor electrodes. The graphene oxide (GO)/PANI colloid layer is drop-coated onto carbon cloth (CC) before evaporating most of the water. The as-obtained hydrated GO/PANI/CC film undergoes a facile hydrazine reduction treatment and yields the porous reduced GO (rGO)/PANI active layer fixed on the CC current collector, which could directly act as the binder-free supercapacitor electrode. As a result, the excellent adhesion of active layer with CC and the uniform PANI distribution on porous rGO matrix contribute greatly to the fast electron and ion transport in the electrochemical activities. The integrated rGO/PANI/CC electrode achieves a high specific capacitance of 871.5 F g−1 at the current density of 1.5 A g−1 with superior rate performance. More importantly, repeating the drop-coating/water-evaporating process could conveniently realize the high rGO/PANI mass loading (up to 10 mg cm−2) on the current collector. The corresponding symmetric all-solid-state supercapacitors with different mass loadings can deliver the maximum energy densities of 39.1 Wh kg−1, 425.3 μWh cm−2, and 4.0 mWh cm−3, manifesting their promising practical prospect. This work would provide a new path for the fabrication of graphene-based supercapacitor electrodes and other functional film materials. [ABSTRACT FROM AUTHOR]

• A novel active layer configuration with enhanced interfacial effect is proposed. • Reduced graphene oxide film is cut into two for each polyaniline electrodeposition. • The twin composite films are parallelly assembled for supercapacitor electrode. • The electrode displays excellent specific capacitance and cycling stability. • The all-solid-state device exhibits high energy density toward application potential. For the traditional supercapacitors based on the graphene@polyaniline (PANI) film prepared by electropolymerization, the interfacial contact between the graphene substrate and PANI shell plays a vital role in improving the PANI stability and the electrochemical capacitance of the active layer. In this work, we propose a novel strategy that the reduced graphene oxide (RGO) hydrogel film with given size could be divided into two for respective PANI electrodeposition and the two graphene@PANI films are assembled parallelly on carbon cloth to obtain the supercapacitor electrode. Owing to the additional lateral RGO/PANI interface, the resulting electrode delivers a high specific capacitance of 949 F g−1 at 1 A g−1 and 760 F g−1 even at the high current density of 20 A g−1. The corresponding binder-free symmetric supercapacitor device could attain a maximum energy density of 18.2 Wh kg−1 and a maximum power density of 4.75 kW kg−1, with a high capacitance retention of 93.1% after 10000 charge/discharge cycles. These superior properties of the electrodes based on the parallel RGO/PANI films testify the rational design of the active layer configuration for enhanced interfacial effect. This work would provide a novel pathway towards the preparation of high-performance supercapacitor electrodes. [Display omitted] [ABSTRACT FROM AUTHOR]

Three dye-functionalized graphene oxide/polyaniline (GAP) composites were first prepared by optimizing acid blue 74 (AB74) feed content, and then dye-functionalized graphene/polyaniline (rGAP) nanocomposites were obtained from the GAP composites through reducing and re-protonating treatments. The AB74 dye molecules with negatively charged sulfonic groups can effectively prevent aggregation of graphene sheets during the reduction process of graphene oxide, and can be used as a bridge to attach polyaniline nanorods via π–π conjunction and electrostatic attraction. Furthermore, when rGAP5 (the AB74 feed content of 5 wt.%) was used as a supercapacitor electrode material, it achieved a high specific capacitance of 579 F g −1 at a current density of 0.5 A g −1 , good cycling stability and rate capacity. [ABSTRACT FROM AUTHOR]