Supercapacitors with a broad operational temperature range, especially with the capability of operating at low temperature (below -50°C), are required for applications in extreme environments. This paper presents a high performance supercapacitor, consisting of highly aligned nano-porous graphene (A-NPG) with an eutectic mixture of ionic liquids (ILs), 1-butyl-4-methylpyridinium tetrafluoroborate (BMPBF4) in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4), which exhibits a high capacitance performance over a temperature range from -50°C to 80°C. The experimental results reveal a reducing of melting temperature Tm of the eutectic mixture to -74°C, compared with -39°C of BMIBF4. The increased ionic conductivity and reduced Tm of the eutectic mixture, combined with ultrahigh density A-NPG electrodes, enable the supercapacitor to show a high capacitance of 125 F cm-3 at room temperature and 106 F cm-3 at -50°C. In contrast, the supercapacitor with pure BMIBF4 shows a capacitance of 119 F cm-3 and 16.5 F cm-3 at room temperature and -50°C, respectively.
ASJC Scopus subject areas
- Chemical Engineering(all)