Design and development of NbTiVZr porous high entropy alloys for energy applications

Abstract

Porous NbTiVZr refractory high entropy alloys have been developed by a novel method that is based on the addition of yttrium to the base high entropy alloy and its subsequent removal by electrochemical dealloying process. Microstructure and crystal structure characterization of as-cast alloys confirmed the segregation of yttrium at interdendritic regions. Successful removal of yttrium from interdendritic region has been confirmed by microstructure and crystal structure characterization of dealloyed samples. NbTiVZr foams with varying levels of porosity were successfully developed and characterized. Electrochemical performance of the developed foams was investigated by cyclic voltammetry (CV), galvanostatic charge discharge (GCD), and electrochemical impedance spectroscopy (EIS). High areal capacitance of 82.66 mF cm−2 at scan rate of 2 mV s−1 was exhibited by one of the developed electrodes. The electrode displayed capacitance retention of 104 % after 5000 cycles at current density of 1 mA cm−2. The excellent electrochemical performance demonstrated by the NbTiVZr refractory high entropy foams highlights their potential as suitable candidates for supercapacitor electrode.