Micron-sized Na0.7MnO2.05 as cathode materials for aqueous rechargeable magnesium-ion batteries

Aqueous magnesium ion batteries have been identified as potential electrochemical energy storage system due to their similar electrochemical properties to lithium, safety, high abundance, and low cost. Here, micron-sized Na0.7MnO2.05 is prepared by a facile sol-gel method used for cathode material in aqueous magnesium ion batteries. XRD, XPS, SEM, TEM, and EDS were used to test the composition, structure, and morphology of Na0.7MnO2.05. Na0.7MnO2.05 material is electro-chemical active although the intercalation/deintercalation is much difficult for Mg2+. The reversible specific capacities of the Na0.7MnO2.05 cathode material are estimated to be ca. 40, 35, 22, and 13 mAh center dot g(-1) at the current density of 1 C, 2 C, 5 C, and 10 C, respectively. When the current density comes back to 1 C, the charge capacities recover to 40 mAh center dot g(-1). Furthermore, EIS and GITT measured show that the diffusion coefficient of Mg2+ ion in lattice of Na0.7MnO2.05 varies from 2.17 x 10(-11) cm(2)center dot s(-1) to 7.81 x 10(-11) cm(2)center dot s(-1) in charge process and changes from 6.34 x 10(-12) cm(2)center dot s(-1) to 7.14 x 10(-11) cm(2)center dot s(-1) in discharge process.