LAUSR

Abstract Early transition metal nitrides achieve high capacitances via a pseudocapacitive mechanism that involves redox reactions with protons at their surfaces. Typically aqueous electrolytes are the source of protons, therefore the operating voltages are limited to ~ 1.2 V. Protic ionic liquid (PIL) based electrolytes offer the possibility of significantly higher operating voltages and energy densities. This paper describes the behavior of VN and TiN in a PIL consisting of 2-methylpyridine and trifluoroacetic acid. These nitrides can be cycled up to 2.0 V in this electrolyte. Voltammograms for VN and TiN in the PIL and aqueous electrolytes were similar suggesting similar pseudocapacitive mechanisms. The use of PIL electrolytes instead of aqueous electrolytes could significantly increase the energies of nitride-based supercapacitors without significant losses in power.