High-Voltage Stabilization of O3-Type Layered Oxide for Sodium-Ion Batteries by Simultaneous Tin Dual Modification

O3-type layered oxide materials are considered to be a highlysuitable cathode for sodium-ion batteries (NIBs) due to their appreciable specificcapacity and energy density. However, rapid capacity fading caused by seriousstructural changes and interfacial degradation hampers their use. A novel Sn-modified O3-type layered NaNi1/3Fe1/3Mn1/3O2cathode is presented, withimproved high-voltage stability through simultaneous bulk Sn doping and surfacecoating in a scalable one-step process. The bulk substitution of Sn4+stabilizes thecrystal structure by alleviating the irreversible phase transition and lattice structuredegradation and increases the observed average voltage. In the meantime, thenanolayer Sn/Na/O composite on the surface effectively inhibits surface parasiticreactions and improves the interfacial stability during cycling. A series of Sn-modified materials are reported. An 8%-Sn-modified NaNi1/3Fe1/3Mn1/3O2cathode exhibits a doubling in capacity retention increaseafter 150 cycles in the wide voltage range of 2.0-4.1 VvsNa/Na+compared to none, and 81% capacity retention is observed after200 cycles in a full cellvshard carbon. This work offers a facile process to simultaneously stabilize the bulk structure and interface forthe O3-type layered cathodes for sodium-ion batteries and raises the possibility of similar effective strategies to be employed forother energy storage materials