期刊
ADVANCED FUNCTIONAL MATERIALS
卷 31, 期 51, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.202106923
关键词
anionic redox chemistry; density functional theory calculations; layered oxide cathodes; reaction mechanisms; sodium-ion batteries
类别
资金
- National Natural Science Foundation of China [21805007, 22075016]
- Fundamental Research Funds for the Central Universities [FRF-TP-20-020A3, FRF-TP-18-091A1]
- 111 Project [B12015, B170003]
A novel P2-Na0.76Ca0.05[Ni0.230.08Mn0.69]O-2 cathode material with joint cationic and anionic redox activities has been developed, showing enhanced energy density and cycling stability. This research provides new opportunities for designing high-energy-density and high-stability layered sodium oxide cathodes through tuning local chemical environments.
Triggering the anionic redox chemistry in layered oxide cathodes has emerged as a paradigmatic approach to efficaciously boost the energy density of sodium-ion batteries. However, their practical applications are still plagued by irreversible lattice oxygen release and deleterious structure distortion. Herein, a novel P2-Na0.76Ca0.05[Ni0.230.08Mn0.69]O-2 cathode material featuring joint cationic and anionic redox activities, where native vacancies are produced in the transition-metal (TM) layers and Ca ions are riveted in the Na layers, is developed. Random vacancies in the TM sites induce the emergence of nonbonding O 2p orbitals to activate anionic redox, which is confirmed by systematic electrochemical measurements, ex situ X-ray photoelectron spectroscopy, in situ X-ray diffraction, and density functional theory computations. Benefiting from the pinned Ca ions in the Na sites, a robust layered structure with the suppressed P2-O2 phase transition and enhanced anionic redox reversibility upon charge/discharge is achieved. Therefore, the electrode displays exceptional rate capability (153.9 mA h g(-1) at 0.1 C with 74.6 mA h g(-1) at 20 C) and improved cycling life (87.1% capacity retention at 0.1 C after 50 cycles). This study provides new opportunities for designing high-energy-density and high-stability layered sodium oxide cathodes by tuning local chemical environments.
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