Structural characterization of layered Na 0.5 Co 0.5 Mn 0.5 O 2 material as a promising cathode for sodium-ion batteries
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Journal of Power Sources, ISSN: 0378-7753, Vol: 363, Page: 442-449
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- Energy; Chemistry; Engineering; Mixed hydroxy-carbonate; Layered structure; Charge-discharge cycling; Cathode performance; Sodium-ion battery
Layered Na 0.5 Co 0.5 Mn 0.5 O 2 material is synthesized through a facile mixed hydroxy-carbonate route using (Co 0.5 Mn 0.5 ) 2 (OH) 2 CO 3 precursor and well characterized as a hexagonal layered structure under P 6 3 / mmc space group. The lattice parameters and unit cell volume (a = 2.8363 Å, c = 11.3152 Å and V = 78.83 Å 3 ) are calculated by Rietveld refinement analysis. A flaky-bundle morphology is obtained to the layered Na 0.5 Co 0.5 Mn 0.5 O 2 material with the hexagonal flake size ∼30 nm. Advanced transmission electron microscopic images are revealed the local structure of the layered Na 0.5 Co 0.5 Mn 0.5 O 2 material with contrasting bright dots and faint dark dots corresponding to the Co/Mn and Na atoms. Two oxidation and reduction peaks are occurred in a cyclic voltammetric analysis corresponding to Co 3+ /Co 4+ and Mn 3+ /Mn 4+ redox processes. These reversible processes are attributed to the intercalation/de-intercalation of Na + ions into the host structure of layered Na 0.5 Co 0.5 Mn 0.5 O 2 material. Accordingly, the sodium cell is delivered the initial charge-discharge capacity 53/144 mAh g −1 at 0.5 C, which cycling studies are extended to rate capability test at 1 C, 3 C and 5C. Eventually, the Na-ion full-cell is yielded cathode charge-discharge capacity 55/52 mAh g −1 at 0.212 mA and exhibited as a high voltage cathode for Na-ion batteries.