Enhancing the Electrochemical Performance by Structural Evolution in O3- NaFe1-xMgxO2 Cathodes for Sodium Ion Batteries

Abstract The structural evolution of electrode materials directly influences the performance of sodium-ion batteries. In the present report we have chosen O3- NaFe1-xMgxO2 system in which different ratios (X= 0.1, 0.2, 0.4, 0.5) for investing through hydrothermal synthesis. The prepared material was confirmed by Rietveld refinement method and morphology was confirmed by FESEM and HRTEM analysis. The prepared samples were fabricated into coin cells and electrochemical test was performed and the migration of Fe ions into Na layer which results capacity fade during cycling. In the present work the active participation of Mg ions at higher operating voltages the stabilization of Fe ions take place which results in migration of Fe ions into Na layer which was greatly reduced. Among different ratios, NaFe0.5 Mg0.5 O2 delivers the higher reversible capacity of 158 mAh g-1 at 50 mA/g with the capacity retention of 85-90% after 100 cycles. This performance shows that the structural changes in the cathodes allow to design high cathodes for Na ion batteries in future.