Preparation And Characterisation Of Battery-Grade Na2mn3o7 As A Cathode Material From Manganese Ore

Natural battery-grade manganese dioxide with 69.78 mass% MnO2 and 14.50% MnCO3 was subjected to solid-state treatment to prepare a hybrid system with beta-MnO2 and Na2Mn3O7 phases. The heat treatment was carried out at 400 degrees C using NaOH/MnO2 molar ratios ranging 0.4 to 1.2 and NaNO3/MnO2 molar ratios ranging 0 to 0.8. The structures of the samples were analysed using X-ray diffraction and differential scanning calorimetry. The electrochemical properties were evaluated through cyclic voltammetry, and the specific capacitance (CS) values were calculated. The XRD results confirmed the formation of Na2Mn3O7. The highest CS (34.21 F g(-1)) was obtained in the sample with 24.15 mass% Na2Mn3O7. A thermodynamic analysis was also carried out to estimate the effect of the NaOH and NaNO3 contents and of the temperature on the formation of Mn-based species.