Synthesis temperature influence on the structure, morphology and electrochemical performance of NaxMnO2 as cathode materials for sodium-ion rechearchable batteries

Abstract

The lithium-ion batteries are the most commonly used for energy storage in portable devices. Since lithium is relatively rare on earth but rapidly consumed, it is necessary to find an adequate replacement. Owing to the similar chemical properties of sodium and lithium, but much higher availability, sodium ion batteries are one of the best candidates to replace lithium-ion batteries. A variety of materials such as manganese oxide, vanadium oxide or phosphate can be used as an electrode material (anode and cathode) in sodium ion batteries due to the high ability of intercalation of sodium. In this work, NaxMnO2 powder was synthesized by glycine nitrate method. The precursor powder was annealed for four hours at different temperatures: 800, 850, 900 and 950 °C. The characterization of the obtained materials was carried out using following methods: X-ray diffraction (XRD), scanning electron spectroscopy with energy dispersive X-ray spectroscopy (SEM/EDS) and transmission electron spectroscopy with energy dispersive Xray spectroscopy (TEM/EDS). Electrochemical properties were studied using cyclic voltammetry and chronopotentiometry in an aqueous solution of NaNO3. The layer structured Na0.7MnO2.05 with sheet-like morphology and Na0.4MnO2 with 3-D tunnel structure and rod-like morphology was obtained at 800 oC and 900 oC respectively. Na0.44MnO2 with rod-like morphology was annealed at 900 and 950 oC. 3D-tunnel structure Na0.44MnO2 obtained at 900 oC showed the best electrochemical behaviour in aqueous NaNO3 solution.