Structure and capacitive properties of porous nanocrystalline VN prepared by temperature-programmed ammonia reduction of v2O5

Abstract

Vanadium nitride (VK) is currently one of the most promising materials for electrodes of supercapacitors. The structure and electrochemical properties of VN synthesized by temperatureprogrammed NH3 reduction of V 2O5 are analyzed in this paper. Vanadium nitride produced via this route has distinctive structural characteristics. VN mimics the shape of the initial V2O5 precursor indicating a pronounced direct attachment of nitride grains. The particles have domains of grains with a preferential orientation (texture). The large volume of pores in VN is represented by the range of 15-110 nm. VN demonstrates capacitive properties in three different types of aqueous electrolytes, 1 M KOH, 1 M H2SO 4, and 3 M NaCl. The material has an acceptable rate capability in all electrolytes, showing about 80% of its maximal capacitance at a current load of 1 A/g in galvanostatic charging/discharging experiments. The capacitance of 186 F/g is observed in 1 M KOH electrolyte at 1 A/g. The previously reported negative effect of material loading on the capacitance is significantly suppressed. The observed electrochemical characteristics related to the application of this material in supercapacitors can be correlated with the crystalline structure of the nitride and the composition of its surface layer. © 2009 American Chemical Society.