Nanostructured porous CrN thin films by oblique angle magnetron sputtering for symmetric supercapacitors

Abstract

Transition metal nitrides become promising electrode materials for supercapacitors due to high chemical stability and electrical conductivity. This study reports a facile (one step) and green (mixed atmosphere of argon and nitrogen without any external heating) strategy for fabricating nanostructured porous transition metal nitride thin films by oblique angle magnetron sputtering and their applications as binder-free electrode materials for symmetric supercapacitors. Using CrN as a demonstration, the thin film electrode shows a high specific capacitance of 17.7 mF cm−2 at a current density of 1.0 mA cm−2, exceeding most of previously reported transition metal nitrides by normal magnetron sputtering. Furthermore, a symmetric supercapacitor device based on nanostructured porous CrN thin film can deliver maximum energy and power densities of 7.4 mWh cm−3 and 18.2 W cm−3 respectively, along with good cycling stability (92.2% capacitance retention after 20000 cycles at a current density of 2.0 mA cm−2). Specially, the oblique angle magnetron sputtering can serve as a versatile route to fabricate nanostructured porous transition metal nitrides for electrochemical energy storage and conversion.