Gel electrolytes and aerogel electrodes from ILs-based emulsions for supercapacitor applications

Abstract

Electrochemical double-layer supercapacitors as advanced energy storage devices have the properties of portability and stable performance. Electrode materials and functional electrolytes as important components of supercapacitors have become the most research filed. Here, we strategically established an oil-in-water (O/W) emulsion, which was synergistically stabilized by a cationic polymerizable ionic liquids ([VCnIm]Br) and similarly charged upconversion nanoparticles (UCNPs). The O/W emulsion was used as template to prepare emulsion gel by polymerizing monomers of [VCnIm]Br (n = 4 and 12) in the continuous phase. When using monomer, [VC4Im]Br, the emulsion gels can be acted as electrolytes, showing considerably high ionic conductivity (8.42 mS cm−1), excellent mechanical strength, superior thermal stability and freezing resistance. While monomer, [VC12Im]Br, was used, the hierarchically porous aerogels were obtained after the emulsion gel being freeze-dried. The all-solid-state supercapacitors were fabricated by assembling the emulsion gels as electrolytes and the aerogels as electrode materials. UCNPs not only served as the stabilizer to synergistically stabilize the O/W emulsion, but also can act as a photovoltaic converter achieving photoelectric conversion performance. The supercapacitor presents large energy density, power density, and promising stability.