High-Entropy Na-Deficient Layered Oxides for Sodium-Ion Batteries

Sodium layered oxides always suffer from sluggish kinetics and deleterious phase transformations at deep-desodiation state (i.e., >4.0 V) in O3 structure, incurring inferior rate capability and grievous capacity degradation. To tackle these handicaps, here, a configurational entropy tuning protocol through manipulating the stoichiometric ratios of inactive cations is proposed to elaborately design Na-deficient, O3-type NaxTmO2 cathodes. It is found that the electrons surrounding the oxygen of the TmO6 octahedron are rearranged by the introduction of MnO6 and TiO6 octahedra in Na-deficient O3-type Na0.83Li0.1Ni0.25Co0.2Mn0.15Ti0.15Sn0.15O2−δ (MTS15) with expanded O–Na–O slab spacing, giving enhanced Na+…

• NN
  National Natural Science Foundation of China

  Awards: U21A20284, 52261135632
• NK
  National Key Research and Development Program of China

  Award: 2019YFC1907805