Na2FeF4 as a stable cathode material for Na-ion batteries
Abstract
In the search of cathode materials for Na-ion batteries, iron-based compounds have attracted much attention due to the abundant resource, easy access, and environmental friendliness of iron. Herein, we report the synthesis, structure, and electrochemistry of a previously unknown compound in the Na–Fe–F system, formulated as Na2FeF4. It is prepared by an easy and mild hydrothermal reaction with oxalate as a Fe2+ protector. Based on the single crystal x-ray diffraction analysis, it crystallizes in space group Pmcb with a = 3.255 (3) Å, b = 5.591(7) Å, and c = 9.557(1) Å. The crystal structure features edge-sharing FeF6 octahedra to form [FeF4]∞ chains with Na+ ions located between chains. In electrochemical investigations, it is demonstrated that the material can deliver a reversible capacity of ∼90 mAh g−1 for 300 cycles in the window of 1.5–4.3 V with redox reactions at ∼3.0 V (vs Na+/Na). Such an activity originates from the Fe3+/Fe2+ redox couple, confirmed by x-ray absorption spectra and first-principles calculations.
Citation
Yan , Q , Xu , H , Hoang , K , Zhou , X , Kidkhunthod , P , Lightfoot , P , Yao , W & Tang , Y 2022 , ' Na 2 FeF 4 as a stable cathode material for Na-ion batteries ' , Applied Physics Letters , vol. 121 , no. 14 , 143902 . https://doi.org/10.1063/5.0111765
Publication
Applied Physics Letters
Status
Peer reviewed
ISSN
0003-6951Type
Journal article
Description
The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China (Nos. 52125105, 22005329, and 51972329), the NSFC/RGC Joint Research Scheme (Nos. 52061160484 and N_CityU104/20), the Shenzhen International Collaboration Research Project (No. GJHZ20210705141407023), the Shenzhen Science and Technology Planning Project (Nos. JCYJ20190807172001755 and JCYJ20200109115624923), and the Science and Technology Planning Project of Guangdong Province (Nos. 2019A1515110975, 2021A1515010184, and 2019TX05L389).Collections
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