High stability and long cycle life of rechargeable sodium-ion battery using manganese oxide cathode: A combined density functional theory (DFT) and experimental study - data

Sodium-ion batteries (SIBs) can develop cost-effective and safe energy storage technology for substantial energy storage demands. In this work, we have developed manganese oxide (α-MnO2) nanorods for SIB applications. The crystal structure, which is crucial for high-performance energy storage, is examined systematically for the metal oxide cathode. The intercalation of sodium into the α-MnO2 matrix was studied using the theoretical density functional theory (DFT) studies. The DFT studies predict Na ions’ facile diffusion kinetics through the MnO2 lattice with an attractively low diffusion barrier (0.21 eV). When employed as a cathode material for SIBs, MnO2 showed a moderate capacity (109 mAh·g–1 at C/20 current rate) and superior life cyclability (58.6% after 800 cycles) in NaPF6/EC+DMC (5% FEC) electrolyte. It shows a much higher capacity of 181 mAh·g–1 (C/20 current rate) in NaClO4/PC (5% FEC) electrolyte, though it suffers fast capacity fading (11.5% after 800 cycles). Our findings show that high crystallinity and hierarchical nanorod morphology of the MnO2 are responsible for better cycling performance in conjunction with fast and sustained charge-discharge. The data underpinning the work is available in the .xlsx format (can be viewed either by MS Office or Libre Office) comprising 6 datasheets named according to their Figure numbers as they appear in the manuscript. The experimental XRD, XPS, Electrochemical charge-discharge curves, galvanostatic charge-discharge (GCD) profiles are provided. The data for the optimized structures of the pristine and Na-intercalated α-MnO2 are available in CONTCAR format of the VASP simulation program and can be visualized using the VESTA software. The projected density of states (PDOS) data has two columns (Energy on the x-axis, and DOS on the y-axis).