Efficient Method of Designing Stable Layered Cathode Material for Sodium Ion Batteries Using Aluminum Doping

Despite their high specific capacity, sodium layered oxides suffer from severe capacity fading when cycled at higher voltages. This key issue must be addressed in order to develop high-performance cathodes for sodium ion batteries (SIBs). Herein, we present a comprehensive study on the influence of Al doping of Mn sites on the structural and electrochemical properties of a P2–Na 0.5 Mn 0.5– x Al x Co 0.5 O 2 ( x = 0, 0.02, or 0.05) cathode for SIBs. Detailed structural, morphological, and electrochemical investigations were carried out using X-ray diffraction, cyclic voltammetry, and galvanostatic charge–discharge measurements, and some new insights are proposed. Rietveld refinement confirmed that Al doping caused TMO 6 octahedra (TM = transition metal) shrinkage, resulting in wider interlayer spacing. After optimizing the aluminum concentration, the cathode exhibited remarkable electroc…