Construction of high performance aqueous asymmetric supercapacitor based on multi walled carbon nanotube/MgMn₂O₄ composite

MgMn₂O₄ nanoplates like structure are synthesized by fast and easiest co-precipitation method. The end product is figured out by numerous characteristic techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), field emission electron microscope (FESEM), selected area electron diffraction (SAED) and Brunauer-Emmett-Teller (BET) surface area analysis. Further, the nanostructure material is subjected as electrode material for energy storage performance. The specific capacitance of 821 F g⁻¹ is observed at 1 A g⁻¹ from MgMn₂O₄ nanoplates. The specific capacitance of prepared MgMn₂O₄ nanomaterial is further boosted by small amount of multi walled carbon nanotubes (MWCNTs) and, high specific capacitance of 1208 F g⁻¹ is observed at 1 A g⁻¹ from MWCNT/MgMn₂O₄ composite. Furthermore, the aqueous asymmetric supercapacitor (ASC) is constructed where MWCNT/MgMn₂O₄ is used as positive electrode and activated carbon (AC) is used as negative electrode. The ASC device reveals the high energy density of 54.39 W h kg⁻¹ with power density of 775.46 W kg⁻¹ at 1 A g⁻¹. Furthermore, two parallel connected red color light-emitting diodes (LEDs) are lit by series connected two ASCs. In addition, a kitchen timer and toy motor fan are also powered by series connected two ASCs. The enhanced supercapacitive performance of composite material is ascribed to the surface roughness of nanoplates, where small voids on the surface of the nanoplates provide more accommodation for electrolytic ions, and connectivity of nanoplates through MWCNTs provide suitable electronic path for electrons/ions during charging/discharging process. This attractive performance reveals that MWCNT/MgMn₂O₄ may be considered as prospective electrode material for high energy storage performance of supercapacitors.