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Mitigating the P2-O2 phase transition of high-voltage P2-Na2/3[Ni1/3Mn2/3]O2 cathodes by cobalt gradient substitution for high-rate sodium-ion batteries
被引:56
|作者:
Hou, Peiyu
[1
]
Li, Feng
[2
]
Wang, Yangyang
[2
]
Yin, Jiangmei
[1
]
Xu, Xijin
[1
]
机构:
[1] Univ Jinan, Sch Phys & Technol, Jinan 250022, Shandong, Peoples R China
[2] Nankai Univ, Natl Inst Adv Mat, Sch Mat Sci & Engn, Tianjin 300350, Peoples R China
基金:
中国国家自然科学基金;
关键词:
LAYERED OXIDE CATHODES;
HIGH-ENERGY DENSITY;
LONG-LIFE;
ELECTROCHEMICAL PERFORMANCE;
ELECTRODE MATERIALS;
POSITIVE-ELECTRODE;
PHOSPHONATE;
CARBON;
FABRICATION;
MODULATION;
D O I:
10.1039/c8ta10980j
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
High-voltage P2-Na-2/3[Ni1/3Mn2/3]O-2 as a high energy density cathode for sodium-ion batteries (SIBs) has attracted considerable attention. But the unfavorable P2-O2 phase transition and electrode/electrolyte side reactions easily occur when charged above 4.2 V (vs. Na/Na+), resulting in the rapid decay of capacity. Here, for the first time, a nanoscale cobalt gradient substitution is introduced to build a Co-enriched surface and cobalt-substituted interior, in which the cobalt-enriched surface is expected to reduce the side reactions and improve the Na+ kinetics while the cobalt substitution is supposed to mitigate the P2-O2 transition. Correspondingly, this gradient cobalt substituted P2-Na-2/3[Ni1/3Mn2/3]O-2 delivers a large reversible capacity of 164.6 mA h g(-1) with a high median potential of 3.55 V, achieving a high energy density of approximate to 585 W h kg(-1) and is comparable to the LiCoO2 cathode in lithium-ion batteries. As anticipated, it shows a mitigated P2-O2 transition and thus exhibits an improved cycling stability. Besides, it delivers a much higher capacity of 110 mA h g(-1) at a high rate of 10C than reported pristine and modified electrodes by bulk doping and surface coating, indicating better high-rate properties. These gratifying achievements make this nanoscale gradient substitution an effective approach for suppressing the P2-O2 transition and improving the Na+ kinetics of P2-Na-2/3[Ni1/3Mn2/3]O-2 cathodes.
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页码:4705 / 4713
页数:9
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