Facile synthesis of P2-type Na0.4Mn0.54Co0.46O2 as a high capacity cathode material for sodium-ion batteries

Abstract

Sodium-ion batteries have received great attention because of the abundant sodium resources and low cost. As a typical kind of cathode material for Na-ion batteries, sodium manganese oxides have shown great potential in cathode application due to their high specific capacity and good rate capability. Herein, we successfully synthesized P2-type Na_0.4Mn_0.54Co_0.46O₂ nanosheets via a two-step annealing route. The morphology and structural information of the Na_0.4Mn_0.54Co_0.46O₂ products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) technologies. The electrochemical performances of Na_0.4Mn_0.54Co_0.46O₂ were measured by charge–discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). As the cathode for Na-ion batteries, the layered Na_0.4Mn_0.54Co_0.46O₂ nanosheets showed a high second charge capacity of 194 mA h g⁻¹ and delivered a specific capacity of 125 mA h g⁻¹ at a current of 20 mA g⁻¹ after 60 cycles.