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

O3-type layered transition metal oxides (Na x TMO 2 ) 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 x TMO 2 . Herein, a Ti-substituted NaNi 0.5 Co 0.2 Mn 0.3 O 2 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.