Thermal behavior, mineral phase, and microstructure characteristics of Na<sub>2</sub>Mn<sub>3</sub>O<sub>7</sub> synthesized from MnO<sub>2</sub> and MnCl<sub>2</sub> via a low-cost, simple conventional mixing method

Sodium manganese oxide plays an important role in the cathode application of sodium ion batteries. In this study, sodium manganese oxide Na2Mn3O7 (NMO) with a triclinic structure was successfully synthesized via a low-cost, simple conventional mixing method. NaMnO materials were synthesized by mixing Na2CO3 precursors and the two different types of Mn precursors, namely MnO2 by a solid method (the sample C) and MnCl2 by a sol–gel method (the Sample D). The calcination of both samples was carried out at 800 °C for 3 h. The results shown that the thermal behavior and crystal characteristics of the Sample D are slightly better than another one. Nevertheless, the Sample C exhibits a better microstructure, showing rod-like particles more dominant than particular particles. In addition, the Sample C reveals a little bit larger surface area than the Sample D.