Rhombohedral Potassium-Zinc Hexacyanoferrate as a Cathode Material for Nonaqueous Potassium-Ion Batteries

Jongwook W. Heo, Munseok S. Chae, Jooeun Hyoung, Seung Tae Hong

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46 Scopus citations

Abstract

Rhombohedral potassium-zinc hexacyanoferrate K 1.88 Zn 2.88 [Fe(CN) 6 ] 2 (H 2 O) 5 (KZnHCF) synthesized using a precipitation method is demonstrated as a high-voltage cathode material for potassium-ion batteries (PIBs), exhibiting an initial discharge capacity of 55.6 mAh g -1 with a discharge voltage of 3.9 V versus K/K + and a capacity retention of 95% after 100 cycles in a nonaqueous electrolyte. All K ions are extracted from the structure upon the initial charge process. However, only 1.61 out of 1.88 K ions per formula unit are inserted back into the structure upon discharge, and it becomes the reversible ion of the second cycle onward. Despite the large ionic size of K, the material exhibits a lattice-volume change (3%) during a cycle, which is exceptionally small among the cathode materials for PIBs. The distinct feature of the material seems to come from the unique porous framework structure built by ZnN 4 and FeC 6 polyhedra linked via the CN bond and a Zn/Fe atomic ratio of 3/2, resulting in high structural stability and cycle performance.

Original languageEnglish
Pages (from-to)3065-3072
Number of pages8
JournalInorganic Chemistry
Volume58
Issue number5
DOIs
StatePublished - 4 Mar 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 American Chemical Society.

Funding

This work was supported by the Creative Materials Discovery Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT and Future Planning (Grant 2015M3D1A1069707). J.W.H. was also supported by the Korea Institute of Energy Technology Evaluation and Planning and the Ministry of Trade, Industry & Energy of the Republic of Korea (Grant 20174030201590).

FundersFunder number
Ministry of Trade, Industry and Energy20174030201590
Ministry of Science, ICT and Future Planning2015M3D1A1069707
National Research Foundation of Korea
Korea Institute of Energy Technology Evaluation and Planning

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