Studies on micron-sized Na0.7MnO2.05 with excellent cycling performance as a cathode material for aqueous rechargeable sodium-ion batteries

Aqueous rechargeable sodium-ion batteries (ARSB) have great potential as large-scale storage devices owing to their low cost, high energy density, safety, and environmental friendliness. Here, micron-sized Na0.7MnO2.05, fabricated by a facile sol–gel method, is reported as a novel cathode material for ARSB and has been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area electron diffraction/energy dispersive spectroscopy (ED/EDS) and X-ray photoelectron spectroscopy (XPS). As revealed, the material is perfectly synthesized. The Na0.7MnO2.05 electrode delivers an initial charge specific capacity of 42.6 mA h g−1 at a current density of 50 mA g−1. Compared with the capacity of 100th cycle (the highest discharge specific capacity of 52 mA h g−1), a capacity retention of 90.1% after 600 cycles is still observed. Good rate performance and excellent long-term cycling capability are also demonstrated. Unique morphology, medium-sized and mono-disperse particles facilitate the diffusion of Na+ in the electrode, which is also beneficial for Na0.7MnO2.05 electrode to exhibit excellent electrochemical performance.