Disrupting Sodium Ordering and Phase Transitions in a Layered Oxide Cathode. Issue 4 (1st April 2022)

• Record Type: Journal Article
• Authors: Grundish, Nicholas S.; Lyu, Hailong; Seymour, Ieuan D.; Henkelman, Graeme; Khani, Hadi
• Is Part Of: Journal of the Electrochemical Society. Volume 169:Issue 4(2022)
• Publication Date: 2022-04-01
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac60eb
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Layered Nax M O2 cathodes are of immense interest as rechargeable sodium batteries further their development as a lithium-ion battery alternative. However, two primary intrinsic structural issues hinder their practicality—sodium ordering and transition-metal layer gliding during cycling. These phenomena plague the electrochemical profiles of these materials with several unwanted voltage plateaus. A Na + and Fe 3+ substitution for Ni 2+ strategy is employed here to obtain a series of Na3+ x Ni2–2 x Fe x SbO6 (0 ≤ x ≤ 0.5) materials to suppress the structural phenomena that are apparent in O'3-layered Na3 Ni2 SbO6 cathode material. This strategy is successful in obtaining a sloping voltage curve without distinct plateaus—an indication of suppression of the underlying structural phenomena that cause them—at doping concentrations of x ≥ 0.3. The first-cycle coulombic efficiency of the doped compounds is much greater than the starting compound, presumably owing to a kinetic barrier to reforming the full O'3-layered starting materials within the voltage range of 2.5–4.3 V vs Na + /Na. Sodium doping into the M O2 layer thus remains a promising strategy for enabling commercial Na x M O2 cathodes, but further development is required to lower the kinetic barrier for sodium reinsertion into these materials in a useful voltage range to maximize their reversible capacity.