The NaxMnO2 materials prepared by a glycine-nitrate method as advanced cathode materials for aqueous sodium-ion rechargeable batteries

Cathodic material for sodium-ion rechargeable batteries based on Na_xMnO₂ were synthesized by glycine nitrate method and subsequent annealing at high temperatures. Different crystal structures with different morphologies were obtained depending on the annealing temperature: hexagonal layeredα-Na_0.7MnO_2.05 nanoplates were obtained at 850 °C, while 3-D tunnel structured Na_0·4MnO₂ and Na_0·44MnO₂, both with rod-like morphology, were obtained at 800 °C and 900 °C, respectively. The investigations of the electrochemical behavior of obtained cathodic materials in aqueous NaNO₃ solution have shown that Na_0·44MnO₂ obtained at 900 °C has shown the best battery performance. Its initial discharge capacities are 123.5 mA h/g, 113.2 mA h/g, and 102.0 mA h/g at the high current densities of 1000, 2000 and 5000 mA/g, respectively.