Polymer-assisted yttrium surface-enrichment doping of O3-type NaNi1/3Fe1/3Mn1/3O2 cathodes to enhance high voltage and air stability in sodium-ion batteries

Y-surface-doped NaNi 1/3 Fe 1/3 Mn 1/3 O 2 was used as a cathode for a Na-ion battery. A uniform Y surface-enriched region was successfully formed with the assistance of PVA.