**Abstract**

The growing demand of energy storage device has attracted significant attention toward transition metal nitrides because of their remarkable mechanical, electronic, and catalytic applications. Here, sputtered chromium nitride thin films deposited on steel substrate have been used as a working electrode for supercapacitor application. The deposited columnar CrN thin films show (111) and (200) planes of cubic phase. The electrochemical properties of CrN working electrode exhibit high specific capacitance of 41.8 F/g at the scan rate of 5 mV/s with excellent capacitance retention up to 2000 cycles. The supercapacitive performance of the CrN films suggests the potential application for supercapacitors.

**Keywords:** energy storage, supercapacitor, chromium nitride, sputtering

## **1. Introduction**

Increasing impetus for renewable energy has directed the extensive growth of semiconductor technology market during the last decade. Among various energy storage devices, supercapacitor (SC) and lithium-ion battery (LIB) are the most anticipated devices [1]. Comparatively, SCs have better power density, charging/ discharging ability, and reversibility to LIBs. Based on the mechanism, SCs are categorized into electrical double-layer capacitors (EDLCs) and pseudocapacitors [2, 3]. Currently, metal oxides are extensively used for SCs because of their high pseudocapacitance. However, these materials suffer low electrical conductivity and fickle stability during long cycles [4].

Therefore, exploring new materials and design for future advancement of the electrochemical properties of supercapacitors is prime requirement. Recently, metal nitrides are found to be prospective contenders for electrochemical applications because of their exceptional thermal and mechanical stability, high melting point, hardness, and excellent electrical conductivity (4000–55,500 S/cm) [5–11]. Among various metal nitrides, cubic CrN films are widely used in optoelectronics and MEMS applications due to its large bandgap [12, 13]. However, electrochemical capabilities of CrN nanostructured films were not emphasized. CrN films can be synthesized by physical vapor deposition methods, chemical vapor deposition, and ammonolysis [14]. Among these, sputtered CrN films are uniform, reproducible, and highly pure.

Herein, sputtered CrN thin films were deposited on steel substrate. The supercapacitive behavior of CrN working electrodes were examined via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).
