Design and Development of NbTiVZr Porous Alloys for Energy Applications

Abstract

The electrochemical activity and electronic conductivity of multi component metal oxides are at least two orders of magnitude higher than those of single component oxides. Multicomponent porous HEAs are one of the possible candidates in this regard for the supercapacitor electrode. Equiatomic NbTiVZr high entropy alloys with varying concentration of filler element was designed by Thermocalc software and fabricated by arc melting route. As-cast NbTiVZrY HEA consists of two interconnected BCC (Nb, Ti, V, Zr), and Hcp (Y) phases formed by phase separation. 3D foam structure with porosity range (5, 10, 12 and 15 At. %) was obtained by selectively dissolving the Hcp phase in nitric acid solution. When used as an electrode material for supercapacitor, porous high entropy alloy (FS5) exhibits high areal capacitance of 82.66 mF cm-2 as compared to its solid counterpart S1 (1.96 mF cm-2) at the scan rate of 2 mV sec-1. At the current density of 1 mA cm-2, the superior capacitance retention value of 104% after 5000 cycles is also attained. Developed samples also have the capability to operate in wide potential window (ΔV=2V) in 1M Na2SO4 solution making them suitable candidate for integration in devices. Subsequently, the prepared high entropy foams have good potential as electrode material for supercapacitor application.