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- Title
Mitigating Sodium Ordering for Enhanced Solid Solution Behavior in Layered NaNiO<sub>2</sub> Cathodes.
- Authors
Sada, Krishnakanth; Kmiec, Steven; Manthiram, Arumugam
- Abstract
The O‐type layered nickel oxides suffer from undesired cooperative Jahn–Teller distortion stemming from Ni3+ ions and undergo multiple biphasic structural transformations during the insertion/extraction of large Na+ ions, posing a significant challenge to stabilize the structural integrity. We present here a systematic investigation of the impact of substituting 5 % divalent (Mg2+) or trivalent (Al3+ or Co3+) ions for Ni3+ to alleviate Na+ion ordering and perturb the Jahn–Teller effect to enhance structural stability. We gauge a fundamental understanding of the Mg−O and Na−O or Mg−O−Na bonding interactions, noting that the ionicity of the Mg−O bond deshields the electronic cloud of oxygen from Na+ ions. Furthermore, calculations of the Van Vleck distortion modes reveal a relaxation of NiO6 octahedra from Jahn–Teller distortion and a reduced electron density at the interlayer with Mg2+ substitution. Long‐range (operando X‐ray diffraction) and short‐range (magic angle spinning nuclear magnetic resonance) structural analyses provide insights into reduced ordering, allowing a stable continuous solid solution. Overall, Mg‐substitution results in a high‐capacity retention of ~96 % even after 100 cycles, showcasing the potential of this strategy for overcoming the structural instabilities and enhancing the performance of sodium‐ion batteries.
- Subjects
SOLID solutions; MAGIC angle spinning; MAGNESIUM ions; NUCLEAR magnetic resonance; JAHN-Teller effect; CATHODES; ELECTRIC batteries
- Publication
Angewandte Chemie, 2024, Vol 136, Issue 25, p1
- ISSN
0044-8249
- Publication type
Article
- DOI
10.1002/ange.202403865