Tailoring the redox activity of manganese dioxide/cerium dioxide/multi-walled carbon nanotube (MnO2/CeO2/MWCNTs) ternary composites for high capacity coin cell supercapacitors

Abstract

Tailoring nanomaterials has revolutionized the design of novel electrode materials to achieve optimal and reliable energy storage systems. The synergistic effect of ternary composites provides an opportunity to tune the redox activity of electrode materials for the development of high-performance supercapacitors. In the present strategy, manganese dioxide nanorods integrated with cerium dioxide and multi-walled carbon nanotubes (MnO₂/CeO₂/MWCNTs) are synthesized and investigated. The resulting ternary composite possesses rich surface defects, high specific surface area, and enhanced electrochemical kinetics and exhibits a high specific capacitance of 1204 F g⁻¹ at 2.5 A g⁻¹, outperforming binary MnO₂/CeO₂ and pristine MnO₂ nanostructures. The fabricated asymmetric (MnO₂/CeO₂/MWCNTs//AC) coin cell device (ASC) achieves a capacitance of 102 F g⁻¹ at 1 A g⁻¹. Moreover, the ASC device offers an impressive energy density of 36 W h kg⁻¹ at a power density of 800 W kg⁻¹. Furthermore, after 10 000 cycles at 10 A g⁻¹, the device preserves about 94% of its original capacitance. These compelling findings suggest the potential of the MnO₂/CeO₂/MWCNT composite for practically applicable supercapacitors. Additionally, these results advocate for further investigation into the synergistic effects of combining MnO₂ and other rare earth metal oxides along with carbonaceous materials.