Biopolymer-Assisted Synthesis of λ-MnO2Nanoparticles As an Electrode Material for Aqueous Symmetric Supercapacitor Devices

λ-MnO 2 nanoparticles have been successfully synthesized using macromolecules like starch and dextrose. The X–ray diffraction pattern shows the cubic structure of the λ-MnO 2 . Morphological studies show the synthesized particles to be of nanospherical structure. The FTIR spectrum confirms the presence of Mn–O bonds. From the charge–discharge analysis λ-MnO 2 was found to exhibit the highest specific capacitance of 384 F g –1 at a specific current discharge of 1 A g –1 . The symmetric aqueous supercapacitor device exhibits the 44 F g –1 at a specific current discharge of 1 A g –1 . We have obtained higher specific capacitance for λ-MnO 2 in three electrode cell configuration and two electrode supercapacitor cells. This is higher than previous reports of λ-MnO 2 three electrode cell and two electrode systems. All the three electrochemical measurements (cyclic voltammetry, galvanostatic charge–discharge, and impedance) proved that the λ-MnO 2 was a good electrode material for a supercapacitor.