Ti-substituted O3-type layered oxide cathode material with high-voltage stability for sodium-ion batteries

O3-type layered transition metal oxides (Na_xTMO₂) have attracted extensive attention as a promising cathode material for sodium-ion batteries because of their high capacity. However, the irreversible phase transition especially cycled under high voltage remains a concerning challenge for Na_xTMO₂. Herein, a Ti-substituted NaNi_0.5Co_0.2Mn_0.3O₂ cathode with strongly suppressed phase transition and enhanced storage stability is investigated. The Ti substitution effectively inhibits the irreversible phase transition and alleviates the structural change even charged to 4.3 V during the repeated Na⁺ deintercalation process. After storing in air or water, the original O3 phase structure of the material is integrally maintained without the generation of impurity phase. As a result, the as-prepared material shows excellent long-term cycle stability and rate performance when charged to a high voltage of 4.3 V.