Temperature dependent performance analysis of all-oxynitride asymmetric solid-state supercapacitor

Abstract

A facile and scalable urea-based method synthesises chromium oxynitride (CrOxNy) and cerium oxynitride (CeOxNy) nanoparticles instead of the conventional ammonothermal method. These nanoparticles are used to fabricate asymmetric coin cell devices, where CeOxNy is used as a positive electrode, and CrOxNy is used as negative electrode material. The fabricated asymmetric device is subjected to electrochemical characterisation techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), leakage current analysis, and electrochemical impedance spectroscopy (EIS). CV measurement reveals that the device exhibits an areal capacitance of 31.82 mF cm−2 at 10 mV s−1, cycled up to 105 cycles at room temperature (25 °C). Further, the asymmetric device is tested at a range of temperatures (−30 °C to 70 °C) using an environmental climate chamber to explore the temperature tolerance of the device. Measurements reveal that the areal capacitance increases when the testing temperature increases from 10 °C to 70 °C (51.46 % increment observed) and decreases with temperature below the freezing range (0 to −30 °C). Furthermore, temperature-dependent leakage current and cyclic stability are investigated. The temperature-based study highlights the promising nature of an all-oxynitride solid-state asymmetric supercapacitor.