Enhancing Structural of P2-Type Layered Cathode Material for Sodium-Ion Batteries through Cu Substitution

Abstract

Oxygen-redox-based layered cathode materials for Sodium-ion batteries (SIBs) have been recognized as a promising alternative to Lithium-ion batteries (LIBs) due to high energy density and additional capacity in the high voltage. However, their irreversible oxygen-redox activity during cycling leads to structural distortion and capacity fading. Herein, we introduce a layered P2-Na0.75[Li0.15Cu0.15Mn0.7]O2 cathode material, in which Cu substitution improves electro-conductivity and cyclability. Na0.75[Li0.15Cu0.15Mn0.7]O2 delivers a reversible capacity of 170 mAh g-1 at 0.1C in Na cell. Operando-XRD measurement display the material maintain the P2 structure even upon full Na+ extraction and insertion. Furthermore, magnetic susceptibility provide further information Cu2+/Cu3+, Mn3+/Mn4+, and O2-/(O2)n- ion distribution in Na0.75[Li0.15Cu0.15Mn0.7]O2. This research highlight the effect of Li and Cu doping in P2-type layered materials and the contribution of oxygen redox to additional capacity in high voltages, suggesting the potential for future development of cathode materials for Na-ion batteries with oxygen redox.