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- Title
P2-type Fe and Mn-based Na0.67Ni0.15Fe0.35Mn0.3Ti0.2O2 as cathode material with high energy density and structural stability for sodium-ion batteries.
- Authors
Lan, Tianxiang; Wei, Wenfei; Xiao, Shuai; He, Gang; Hong, Jianhe
- Abstract
P2-type layered cathode materials containing Fe and Mn have attracted much attention due to their elemental abundance, low costs and high reversible capacities, and most related work have focused on attaining cathodes with extremely high reversible capacity. However, the extremely high capacity usually leads to several disadvantages, including extremely wide voltage range, fast capacity fading upon cycling, and inappropriate initial Coulombic efficiency. This work investigates P2-type Na0.67Ni0.15Fe0.35Mn0.5O2 (NFM) and Na0.67Ni0.15Fe0.35Mn0.3Ti0.2O2 (NFMT) as high-energy cathode materials by elevating average operating voltage with Ni2+/Ni4+ and Fe3+/Fe4+ redox couples but limiting (de)sodiation in the voltage of 2.0–4.4 V to obtain an medium reversible capacity. NFMT has high energy density of 471 Wh kg−1 with reversible capacity of 157.2 mAh g−1 and average operating voltage of 3.0 V. NFMT also has an initial Coulombic efficiency of 98.8% and a capacity retention of 85.1% after 50 cycles at 20 mA g−1 (0.1C), better than those of some high-capacity P2-type Fe and Mn-based cathodes, showing great potential for future practical application in the sodium full cells. Ti4+ ion acts as pillar ion in the fully charged NFMT cathode, effectively suppressing thickness reduction of the MO2 slab, volume shrinkage of the cathode, and thus inhibiting P2–O2 phase transition at high voltage, which contribute to the improvement of the structural and cycling stability P-type oxides.
- Subjects
ENERGY density; HIGH voltages; CATHODES; ELECTRIC batteries; PHASE transitions; MATERIALS
- Publication
Journal of Materials Science: Materials in Electronics, 2020, Vol 31, Issue 12, p9423
- ISSN
0957-4522
- Publication type
Article
- DOI
10.1007/s10854-020-03482-9