Preserved crystal phase and morphology: Electrochemical influence of copper and iron co-doped cobalt oxide and its supercapacitor applications

Abstract

The cation exchange process is an effective method for improving the electrochemical performance of electrodes in supercapacitors. In this study, the cation (Cu) and co-cation (Cu–Fe) exchanges were achieved in the form of a cobalt oxide crystallite using a chemical bath deposition method, followed by high-temperature calcination. Interestingly, the nanoneedle structure of the as-formed Cu–Fe–Co ternary oxide remained unchanged after calcination, with the crystal phase preserved in the cation exchange process. The novel trimetallic oxide delivered a high specific capacity of 737 C g−1 at 1 A g−1. The Cu–Fe–Co ternary oxide electrode exhibited a low fading rate of only 0.000238% per cycle over 4200 charge-discharge cycles. A fabricated hybrid supercapacitor (HSC) delivered a high-energy density of 48 W h kg−1 and a high-power density of 4800 W kg−1. Integration of the HSC device with solar cells successfully illuminated 52 red LEDs, demonstrating the viability of the prepared electrodes for practical and commercial use.