Mesoporous MnO2 microstructures with large specific surface area have been successfully synthesized by an in-situ redox precipitation method in the presence of colloidal carbon spheres. The samples of them had much higher specific surface area, pore size and pore volume than those obtained via routes without carbon spheres. The morphology, chemical compositions and porous nature of products were fully characterized. Electrochemical measurements showed that these mesoporous MnO2 could function well when used as positive electrode materials for supercapacitor. Ideal electrochemical capacitive performances and cyclic stability after 2000 galvanostatic charge-discharge cycles could be observed in 1 M neutral Na2SO4 aqueous electrolyte with a working voltage of 1.7 V.Graphical AbstractMesoporous MnO2 microstructures with large SBET were successfully synthesized by in-situ redox precipitation method in the presence of colloidal carbon spheres. Electrochemical measurements showed that these mesoporous MnO2 could be well used as electrode materials for supercapacitor. Highlights► Mesoporous MnO2 was prepared by in-situ redox method assisted by carbon spheres. ► SBET, pore size and volume were higher than MnO2 obtained without carbon spheres. ► They could function well when used as electrode materials for supercapacitor. ► Ideal capacitive behaviors and long cycling life showed after 2000 charge–discharge.

Composite nanofibrous electrolyte membranes (CFEM) of poly(vinylidene fluoride-hexafluoropropylene) P(VdF-HFP)-1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and its NaSCN are electrospun as nanofibrous membranes. Scanning electron microscope (SEM) images clearly inform that electrospun CFEM and CFEM–NaSCN with average fiber diameters of 50–200 nm have interconnected multifibrous layers with ultrafine porous structures. They exhibited a high uptake of the electrolyte solution (370–880 %). The polymer electrolytes have decreased crystalline, which is advantage to the increase in ionic conductivity. In addition, polymer electrolytes also are prepared by swelling nanofibre into blend of sodium salt and BMIMBF4. CFEM obtained 15 % BMIMBF4 exhibited higher ionic conductivity maximum of 5.6 × 10−5 S cm−1 at room temperature, and the conductive model of CFEM–NaSCN electrolyte answer for Arrhenius function. CFEM–NaSCN electrolyte showed a high electrochemical window of above 4.5 V, which is higher than electrospun pure P(VdF-HFP) without BMIMBF4 or BMIMBF4–NaSCN. With these improved performance characteristics, CFEM electrolyte and CFEM–NaSCN electrolyte will be found its suitability as polymer electrolyte for high-performance rechargeable batteries and super capacitor.

Polymer electrolytes based on the copolymer of N-vinylimidazolium tetrafluoroborate (VyImBF4) and poly(ethylene glycol) dimethacrylate (PEGDMA) have been prepared. Ethylene carbonate (EC) and LiClO4 are added to form gel polymer electrolytes. The chemical structure of the samples and the interactions between the various constituents are studied by FT-IR. TGA results show that these polymer electrolytes have acceptable thermal stability, are stable up to 155 °C. Measurements of conductivity are carried out as a function of temperature, VyImBF4 content in poly(VyImBF4-co-PEGDMA), and the concentration of EC and LiClO4. The conductivity increases with PEGDMA and EC content. The highest conductivity is obtained with a value of 2.90 × 10− 6 S cm− 1 at room temperature for VP1/EC(25 wt.%)–LiClO4 system, corresponding to the LiClO4 concentration of 0.70 mol kg− 1 polymer.

The copolymer of acrylonitrile (AN), methyl methacrylate (MMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) is synthesized in 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4). The dynamic mechanical properties of the resulting gel polymer electrolytes containing ionic liquid are measured. Results show that the gel polymer electrolytes possess two glass transitions in the temperature range from − 80 °C to 120 °C. Moreover, the storage modulus, loss modulus and the height of tanδ peaks are found to depend on frequency, nature of lithium salt, content of lithium salt and ionic liquid. It is also shown that the activation energy varies with the content of lithium salt and ionic liquid.