MnCo2O4/activated carbon wheat husk (ACWH) as a novel electrode material for electrochemical capacitors

Abstract

Supercapacitors are very suitable devices for energy storage in the coming years. Researches on the introduction of efficient, cost-effective, and environmentally friendly electrodes are still ongoing. In this investigation, we used wheat husk, which is an agricultural waste, for the preparation of carbon with excellent specific surface area to be used in supercapacitors' electrodes. The results of BET analysis showed a specific surface area of 339.04 m2 g−1. In addition to this efficient carbon electrode introduction, we reached the specific capacity of 1392 F/g at current density 1 A/g by the addition of MnCo2O4 composite to the activated carbon wheat husk (ACWH), hence, increasing the conductivity and decreasing the resistance. Also, the results of EIS analysis showed that the resistance due to charge transfer for the wheat husk electrode decreased from about 22 Ω to 3.8 Ω after adding the composite. Comparative investigations were done on the three-electrode system with wheat husk, MnCo2O4, and MnCo2O4/ACWH carbon electrodes. Results indicated that the synergistic effect of the synthesized carbon (with the excellent surface area) along with MnCo2O4 increases the number of active sites and, thus, the specific capacity. Furthermore, using a ACWH improved MnCo2O4 electrode stability so that the synthesized hybrid showed 90.8 % stability after 5000 consecutive cycles.