Graphene-wrapped polyaniline (PANI) nanowire array modified functionalized carbon cloth (fCC) (fCC-PANI array-rGO) is successfully fabricated and served as free-standing electrode for assembling flexible solidstate supercapacitors (SCs). Carbon cloth is functionalized so as to improve both hydrophilicity and capacitance, thus the vertically aligned PANI nanowire arrays are conducive to growth on fCC. After being wrapped with graphene, the fCC-PANI array-rGO electrode exhibits largest capacitance of 471 mF/cm 2 at 0.5 mA/cm 2 . In addition, the graphene layer is employed as protective layer to alleviate swelling and shrinking of PANI in order to improve the cycle stability of fCC-PANI array-rGO. As a result, the free-standing electrode can maintain 75.5% of original capacitance even up to 10 000 cycles. Furthermore, the flexible solid-state SCs based on fCC-PANI array-rGO exhibit an outstanding area capacitance of 197 mF/cm 2 at current density of 0.1 mA/cm 2 , keeping 91.3% of its original value after 7000 cycles at 5 mA/cm 2 . Remarkably, the flexible solid-state SCs exhibit excellent mechanical properties and maintain about 100% of its capacitance, when bent at 180°a fter 500 cycles. Moreover, the flexible solid-state SCs are further employed as energy-storage device to light up a red, green, or yellow LED. Thus, the flexible solid-state SCs based on fCC-PANI array-rGO exhibit potential applications as a candidate for flexible energy-storage devices.

Conductive supports could improve the electrical conductivity of the electrode in lithium–sulfur (Li–S) batteries but suffer from the shuttle effect originated from the polysulfide dissolution, while the hydrophilic metal oxides could avoid the shuttle effect but with poor conductivity. Herein, a facile approach was developed to fabricate hierarchically porous tin oxide (SnO2) nanoparticle-anchored tubular polypyrrole (T-PPy) as a sulfur host, in order to integrate the advantages of conductive supports and metal oxides but overcome their shortcomings. In the unique structure, the T-PPy nanotubes acted as a conductive network to not only improve the electrical conductivity of cathodes but also accommodate the volume expansion of the sulfur cathode during cycling as well as relatively confine the polysulfide diffusion, while the SnO2 nanoparticles served as a high-efficient polysulfide trap to mitigate the shuttle effect due to the chemical bond between SnO2 and polysulfides. Moreover, the hierarchically porous structure and therefore large surface area of the proposed S/(T-PPy)@SnO2 cathode were favorable for the accommodation of sulfur and lithium sulfides. Consequently, S/(T-PPy)@SnO2 with 64.7% sulfur mass content exhibited excellent cyclic stability with a decay rate of only 0.05% per cycle along with 500 cycles at 1 C, rate capability of 383.7 mA h/g at 5 C, and Coulombic efficiency above 90%, outstanding among most of the reported PPy-based sulfur cathodes and PPy-based ternary sulfur cathodes.

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Slightly crumpled aminated graphene nanosheets were prepared via the mild surface modification of graphene oxide (GO) nanosheets with p-phenylenediamine at room temperature to inhibit the restacking of graphene but avoid cross-linking during the solvothermal or microwave-assisted treatments, and then the honeycomb-like flexible graphene/polyaniline (PANI) composite film electrode, PANI@rPGO, was developed by the facile vacuum filtration and reduction. Owing to the slightly crumpled PGO nanosheets with surface amino groups, the honeycomb-like PANI@rPGO composite film, with a well-defined dispersion of PANI nanorods in the graphene-based matrix and the hierarchically porous structure, possessed superior electrochemical performance as a robust electrode in flexible solid-state supercapacitors (SSCs). The symmetric SSCs based on the PANI@rPGO electrode possessed a high capacitance of 564.5 F/g and 2015.2 mF/cm 2 at 0.5 A/g (2.2 mA/cm 2 ), superior cyclic life with retentions of 104.2 and 78.5% after 2000 and 5000 cycles at 3 A/g, as well as excellent flexibility. The mild one-pot preparation and the superior electrochemical performance make the designed PANI@rPGO composite film electrode a potential candidate for high-performance flexible SSCs.