期刊
CHEMPHYSCHEM
卷 23, 期 15, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/cphc.202200248
关键词
rechargeable magnesium batteries; iron diselenide; Mg2+ intercalation cathodes; fading mechanism; cathode dissolution
资金
- Intergovernmental International Science and Technology Innovation Cooperation Project [2019YFE0100200]
- National Natural Science Foundation of China [22179101, 52172266]
The study synthesized nanorod-like FeSe2 as a cathode for rechargeable Mg batteries, demonstrating high capacity and good rate capability. In situ characterizations revealed the Mg2+ intercalation mechanism for FeSe2 and considered the fading mechanism caused by the dissolution of Fe2+ and selenium in the electrolyte during cycling.
Rechargeable Mg batteries (RMBs) are advantageous large-scale energy-storage devices because of the high abundance and high safety, but exploring high-performance cathodes remains the largest difficulty for their development. Compared with oxides and sulfides, selenides show better Mg-storage performance because the weaker interaction with the Mg2+ cation favors fast kinetics. Herein, nanorod-like FeSe2 was synthesized and investigated as a cathode for RMBs. Compared with microspheres and microparticles, nanorods exhibit higher capacity and better rate capability with a smaller particle size. The FeSe2 nanorods show a high capacity of 191 mAh g(-1) at 50 mA g(-1) and a good rate performance of 39 mAh g(-1) at 1000 mA g(-1). Ex situ characterizations demonstrate the Mg2+ intercalation mechanism for FeSe2, and a slight conversion reaction occurs on the surface of the particles. The capacity fading is mainly because of the dissolution of Fe2+, which is caused by the reaction between Fe2+ and Cl- of the electrolyte during the charge process on the surface of the particles. The surface of FeSe2 is mainly selenium after long cycling, which may also dissolve in the electrolyte during cycling. The present work develops a new type of Mg2+ intercalation cathode for RMBs. More importantly, the fading mechanism revealed herein has considered the specificity of Mg battery electrolyte and would assist a better understanding of selenide cathodes for RMBs.
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