Insights into the Improved High-Voltage Performance of Li-Incorporated Layered Oxide Cathodes for Sodium-Ion Batteries

By virtue of their prominent advantages in terms of capacity and voltage output and cost, O3-type layered transition-metal oxides are considered promising cathode materials for sodium-ion batteries (SIBs). However, their unstable electrochemistry at high voltages due to complex multiphase evolution in the bulk structure and continuous degradation of the electrolyte-cathode interphase hampers their practical viability. Here, we reveal a dual-stabilization effect of the cation dopants on the evolution of the bulk structure and electrode-electrolyte interphase of a Li-substituted O3-type cathode upon Na (de) intercalation. The incorporation of Li into the transition-metal layer could mitigate the Jahn-Teller distortion of the Ni3+ ion and prevent the loss of active transition-metal ions so that the unfavorable high-voltage phase transition and the degradation of the electrolyte-cathode interphase are suppressed. As a result, the Li-incorporated cathode material displays a high reversible capacity with good high-voltage durability to facilitate its service in high-energy-density SIBs.