Development Of GO-MnO2 Nanocomposite Based Electro

Abstract

Transition metal oxides exhibit unique properties as catalytic activity, piezoelectricity, and superconductivity and are widely used in energy storage and conversion devices. For energy storage and transfer devices like supercapacitors and batteries have been widely researched on the purpose of obtaining desirable performances. In this work, Manganese based oxide materials synthesized by Modified Hummers method, hydrothermal method and sol-gel technique respectively and their functionalities are investigated as electrode function of supercapacitor devices. The perposed materials are GO, MnO2, GO-MnO2, Li (0.1) doped MnO2 and Li (0.2) doped MnO2. Their investigations consist of various characterizations such as XRD, Raman and FTIR. The XRD pattern of MnO2 (JCPDS: 44-0141) having tetragonal structure. The average crystallite size of MnO2 is 24.34 nm. In XRD pattern of Li (0.1) doped MnO2, the cubic structure of the Mn-O confirmed with JCPDS card: 96-201-9466, average crystallite size (D) is 28.93 nm and the cubic structure of the Li-O confirmed with JCPDS card: 96-151-4099, average crystallite size (D) is 31.09 nm. The orthorhombic structure of the LiMn-O confirmed with JCPDS card: 01-081-1706 and average crystallite size (D) is 22.16 nm. FTIR technique is employed to study the chemical composition and its bonding. All the samples accommodate numerous functional groups like epoxy, carbonyl, hydroxyl, and carboxyl. Raman spectroscopy is used to detect vibrational, rotational, and other states in a molecular system, capable of probing the chemical composition of materials. Electrochemical performance of prepared electrodes was evaluated by cyclic voltammetry (CV), galvanic charge discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The specific capacitance, energy density and power density for GO-MnO2 electrode are 861 Fg-1 at 1Ag-1 , 0.0298Whkg-1 1Ag-1 , and 0.00948Whkg-1 1Ag-1 from GCD curve. From Nyquist plot the MnO2 shows good electrical conductivity as compared to GO-MnO2 and when replace Li with GO the conductivity increased by increasing the ratio of doping material. It is concluded that the electrode material shows good specific capacitance with small value of energy and power density. A computational approach is also used to analyze the thermometric properties such as Seebeck coefficient (S (T)), electrical conductivity (σ (T)), thermal conductivity (k(T)), power factor (P (T)), and figure of xi merits (Z (T)) by software Quantum espresso using Plane-wave approximation which shows that MnO2 having excellent thermoelectric properties.