Effect of lithium doping in P2-Type layered oxide cathodes on the electrochemical performances of Sodium-Ion batteries

Anionic redox reaction offers an effective way to design high-performance cathode materials for sodium-ion batteries. Here to trigger the lattice oxygen redox reaction, the effect of Li doping on the electrochemical performances of P2-type layered oxide cathodes are systematically investigated. Results show that the introduction of Li can not only induce oxygen anions to participate in the charge compensation under high operating voltage, but also suppress the unfavorable P2-O2 transition and facilitate the diffusion of Na+ and electrons during the sodiation/desodiation process. Therefore, Li-doped layered oxide cathodes show improved electrochemical performances with higher reversible capacity, better rate capability, and longer cycling stability. This study may provide a reference point for designing advanced cathode materials through activating the anionic redox reaction.