Preparation and Characterisation of Battery-grade Na2Mn3O7 as a Cathode Material from Manganese Ore
Yolanda Escobar-Martínez, E.M. Arce-Estrada, Antonio Romero‐Serrano, Aurelio Hernández-Ramírez, Josué López-Rodríguez, Alejandro Cruz‐Ramírez, Enrique Rivera-Salinas
Abstract
Natural battery-grade manganese dioxide with 69.78 mass% MnO 2 and 14.50% MnCO 3 was subjected to solid-state treatment to prepare a hybrid system with β-MnO 2 and Na 2 Mn 3 O 7 phases. The heat treatment was carried out at 400°C using NaOH/MnO 2 molar ratios ranging 0.4 to 1.2 and NaNO 3 /MnO 2 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 (C S ) values were calculated. The XRD results confirmed the formation of Na 2 Mn 3 O 7 . The highest C S (34.21 F g −1 ) was obtained in the sample with 24.15 mass% Na 2 Mn 3 O 7 . A thermodynamic analysis was also carried out to estimate the effect of the NaOH and NaNO 3 contents and of the temperature on the formation of Mn-based species.