A highly stable high-energy layered oxide cathode for rechargeable sodium ion batteries

Abstract

Large-capacity layered oxides are highly desirable cathode materials for high-energy rechargeable sodium ion batteries (SIBs); however, they generally suffer from poor cycling stability. Herein, a Li/Ti-dual doped nickel/manganese oxide is rationally designed by introducing Li dopant into NaNi_1/2Mn_1/4Ti_1/4O₂ composition as a new high-performance cathode material for SIBs. Its structural properties and electrochemical evolution are carefully investigated using X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, and galvanostatic measurements. The results reveal that the unique Li/Ti-dual doping structure enables it to undergo highly reversible structural evolutions and electrochemical reactions during Na⁺ extraction/insertion. As a result, it achieves a large practical capacity of 153 mA h g⁻¹ and an impressive coulombic efficiency of 95% at the first cycle and exhibits excellent cycling performance with 83% capacity retention after 200 cycles at 100 mA g⁻¹. The finding suggests that Li/Ti-dual-doped layered oxide is a promising cathode material for constructing SIBs with high energy and long lifespan.