Shao-Wei Bian

Fabrication of Polyaniline/Graphene/Polyester Textile Electrode Materials for Flexible Supercapacitors with High Capacitance and Cycling Stability

Vertical polyaniline (PANI) nanowire arrays on graphene-sheet-coated polyester cloth (RGO/PETC) were fabricated by the in situ chemical polymerization of aniline. The 3D conductive network that was formed by the graphene sheets greatly enhanced the conductivity of PANI/RGO/PETC and improved its mechanical stability. PANI nanowire arrays increased the active surface area of PANI, whilst the hierarchically porous structure of the PANI/RGO/PETC electrode facilitated the diffusion of the electrolyte ions. Electrochemical measurements showed that the composite electrode exhibited a maximum specific capacitance of 1293 F g(-1) at a current density of 1 A g(-1) . Capacitance retention was greater than 95 %, even after 3000 cycles, which indicated that the electrode material has excellent cycling stability. Moreover, the electrode structure endowed the PANI/RGO/PETC electrode with a stable electrochemical performance under mechanical bending and stretching.

Porous WO3/graphene/polyester textile electrode materials with enhanced electrochemical performance for flexible solid-state supercapacitors

In this work, a flexible and porous WO3/grapheme/polyester (WO3/G/PT) textile electrode was successfully prepared by in situ growing WO3 on the fiber surface inside G/PT composite fabrics. The unique electrode structure facilitates to enhance the energy storage performance because the 3D conductive network constructed by the G/PT increase the electron transportation rate, nanotructured WO3 exposed enhanced electrochemically active surface area and the hierarchically porous structure improved the electrolyte ion diffusion rate. The optimized WO3/G/PT textile electrode exhibited good electrochemical performance with a high areal capacitance of 308.2mFcm-2 at a scan rate of 2mVs-1 and excellent cycling stability. A flexible asymmetric supercapacitor (ASC) device was further fabricated by using the WO3/G/PT electrode and G/PT electrode, which exhibited a good specific capacitance of 167.6mFcm-3 and high energy density of 60μWhcm-3 at the power density of 2320 μWcm-3.

MnO2 nanotubes assembled on conductive graphene/polyester composite fabric as a three-dimensional porous textile electrode for flexible electrochemical capacitors

A three-dimensional (3D) electrode material was successfully synthesized through a facile ZnO-assisted hydrothermal process in which vertical MnO2 nanotube arrays were in situ grown on the conductive graphene/polyester composite fabric. The morphology and structure of MnO2 nanotubes/graphene/polyester textile electrode were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The 3D electrode structure facilitates to achieve the maximum number of active sites for the pesudocapacitance redox reaction, fast electrolyte ion transportation and short ion diffusion path. The electrochemical measurements showed that the electrode possesses good capacitance capacity which reached 498F/g at a scan rate of 2mV/s in Na2SO4 electrolyte solution. The electrode also showed stable electrochemical performances under the conditions of long-term cycling, and mechanical bending and twisting.

Core–shell-structured Fe3O4/Pd@ZIF-8 catalyst with magnetic recyclability and size selectivity for the hydrogenation of alkenes

The catalytic activity, recyclability and selectivity are the key issues resisting the noble metal nanocatalysts in the practical applications. In the present work, core–shell-structured Fe3O4/Pd@ZIF-8 catalyst was prepared by in situ coating Fe3O4/Pd microspheres with ZIF-8 shells. The catalyst structure was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption–desorption and X-ray photoelectron spectroscopy. The special catalyst structure which possesses the Fe3O4 cores, Pd nanoparticles and microporous ZIF-8 shells endowed the catalyst with magnetic recyclability, high catalytic activity and size selectivity for the hydrogenation of alkenes. It is believed that this study can provide a promising strategy to prepare core–shell-structured noble metal nanocatalysts with metal-framework shells.

Fabrication of three-dimensional composite textile electrodes by metal-organic framework, zinc oxide, graphene and polyaniline for all-solid-state supercapacitors

Textile electrode materials have attracted intense attention in the flexible supercapacitor field due to their flexibility, light weight, hierarchical porosity and mechanical robustness. However, their electrochemical performance is not good due to the low conductivity, ineffective ion diffusion and small electroactive surface area. In this study, a three-dimensional (3D) textile electrode material was constructed by utilizing ZIF-8 (Zeolitic Imidazolate Framework), metal oxides, conductive polymers and graphene sheets. The polyaniline/ZnO/ZIF-8/graphene/polyester textile electrode exhibited good electrochemical performance with a high areal capacitance of 1.378 F/cm2 at 1 mA/cm2 and high stability under different mechanical deformations. A flexible all-solid-state symmetric supercapacitor device was further fabricated, which can provide a high energy density of 235 μWh/cm3 at a power density of 1542 μW/cm3.

Boosting the electrochemical performance of carbon cloth negative electrodes by constructing hierarchically porous nitrogen-doped carbon nanofiber layers for all-solid-state asymmetric supercapacitors

The electrochemical performance of carbon cloth directly relates to its surface area and porosity, and the functional groups of the primary carbon fibers. In this study, after rationally functionalizing a carbon cloth fiber surface with 3D porous nitrogen-doped carbon nanofiber layers, the resultant 3D hierarchical porous nitrogen-doped carbon nanofibers/carbon cloth negative electrode exhibits superior supercapacitive performance due to its large surface area, suitable porosity, nitrogen-doped carbon surface and fast electron transportation. This electrode delivers high areal capacitance of 608 mF cm−2 at 1 mA cm−2 and good cycle life (capacitance retention of 99% after the 5000th cycle). An asymmetric supercapacitor device is also assembled by using NiO@carbon nanofibers/carbon cloth as the positive electrode and nitrogen-doped carbon nanofibers/carbon cloth as the negative electrode, which exhibits high energy density of 19.5 W h kg−1 at 4.1 kW kg−1.

Flexible hybrid yarn-shaped supercapacitors based on porous nickel cobalt sulfide nanosheet array layers on gold metalized cotton yarns

A high-performance yarn-shaped supercapacitor electrode material with light weight, small volume, flexibility and low cost, is highly desirable for the development of flexible energy storage devices. Herein, a cotton/Au/nickel cobalt sulfide hybrid yarn electrode was designed and synthesized by electrodepositing nickel cobalt sulfide nanosheet arrays on the Au metalized cotton yarn. The metalized cotton yarn as a conductive substrate ensures rapid electron transportation. The porous layer which constructed by CoNi2S4 nanosheet arrays significantly enlarges the interface between the electrolyte ions and electrode materials, providing large electroactive surface area for the faradic redox reactions. The hierarchically porous structure of entire yarn electrode shortens the electrolyte diffusion path. A synergistic effect caused by the unique electrode structure greatly increases the electrochemical performance. This hybrid yarn electrode exhibits high specific capacitance of 1323 F/g at 1 A/g, good electrochemical stability and high flexibility with performance well maintained under the mechanical bending condition. An assembled two-ply structured all-solid-state symmetric supercapacitor device delivers an energy density of 40.9 Wh/kg at a power density of 1.43 kW/kg.