P2-NaCo(0.5)Mn(0.5)O2 as a Positive Electrode Material for Sodium-Ion Batteries

As a promising positive electrode material for sodium-ion batteries (SIBs), layered sodium oxides have attracted considerable attention in recent years. In this work, stoichiometric P2-phase NaCo(0.5)Mn(0.5)O2 was prepared through the conventional solid-state reaction, and its structural and physical properties were studied in terms of XRD, XPS, and magnetic susceptibility. Furthermore, the P2-NaCo(0.5)Mn(0.5)O2 electrode delivered a discharge capacity of 124.3 mA h g(-1) and almost 100% initial coulombic efficiency over the potential window of 1.5-4.15 V. It also showed good cycle stability, with a reversible capacity and capacity retention reaching approximately 85 mA h g(-1) and 99%, respectively, at the 5 C rate after 100 cycles. Additionally, cyclic voltammetry and ex situ XRD were employed to explain the electrochemical behavior at the different electrochemical stages. Owing to the applicable performances, P2-NaCo(0.5)Mn(0.5)O2 can be considered as a potential positive electrode material for SIBs.