Flexible Solid-State Symmetric Supercapacitor Based on (Fe,Cr)2O3 Oxide Layer Developed on the Stainless Steel Mesh

Abstract

The present work describes a simple, easy, and scalable thermal oxidation process for the development of the polygonal structure of the (Fe,Cr)2O3 oxide layer on the stainless steel mesh in an ambient atmosphere. The developed oxide layer shows the maximum areal capacitance of 45.92 mF cm–2 at a scan rate of 5 mV s–1 with an extraordinary capacitance retention of 97% over the 10 000 cycles. Furthermore, a flexible solid-state symmetric supercapacitor is assembled with the (Fe,Cr)2O3 oxide layer as electrodes using polymer-gel electrolyte, which substantially demonstrates a pseudocapacitive nature with the maximum areal capacitance of 16.88 mF cm–2 at a scan rate of 5 mV s–1, capacitance retention of 90% after 10 000 cycles, an energy density (0.57 mWh cm–2) and power density (200 mW cm–2). Furthermore, it demonstrates constant capacitance retention over 500 bending cycles as well as excellent electrochemical durability (90% over 2000 cycles) under bent and twisted conditions. These charming performances s...