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Exploring the Role of Crystal Water in Potassium Manganese Hexacyanoferrate as a Cathode Material for Potassium-Ion Batteries
| Content Provider | MDPI |
|---|---|
| Author | Morozova, Polina Trussov, Ivan Rupasov, Dmitry Nikitina, Victoria Abakumov, Artem Fedotov, Stanislav |
| Copyright Year | 2021 |
| Description | The Prussian Blue analogue $K_{2−δ}Mn[Fe(CN)_{6}]_{1−ɣ}∙nH_{2}$O is regarded as a key candidate for potassium-ion battery positive electrode materials due to its high specific capacity and redox potential, easy scalability, and low cost. However, various intrinsic defects, such as water in the crystal lattice, can drastically affect electrochemical performance. In this work, we varied the water content in $K_{2−δ}Mn[Fe(CN)_{6}]_{1−ɣ}∙nH_{2}$O by using a vacuum/air drying procedure and investigated its effect on the crystal structure, chemical composition and electrochemical properties. The crystal structure of $K_{2−δ}Mn[Fe(CN)_{6}]_{1−ɣ}∙nH_{2}$O was, for the first time, Rietveld-refined, based on neutron powder diffraction data at 10 and 300 K, suggesting a new structural model with the Pc space group in accordance with Mössbauer spectroscopy. The chemical composition was characterized by thermogravimetric analysis combined with mass spectroscopy, scanning transmission electron microscopy microanalysis and infrared spectroscopy. Nanosized cathode materials delivered electrochemical specific capacities of 130–134 mAh $g^{−}$1 at 30 mA $g^{−}$1 (C/5) in the 2.5–4.5 V (vs. $K^{+}$/K) potential range. Diffusion coefficients determined by potentiostatic intermittent titration in a three-electrode cell reached $10^{−13}$ $cm^{2}$ $s^{−1}$ after full potassium extraction. It was shown that drying triggers no significant changes in crystal structure, iron oxidation state or electrochemical performance, though the water level clearly decreased from the pristine to air- and vacuum-dried samples. |
| Starting Page | 895 |
| e-ISSN | 20734352 |
| DOI | 10.3390/cryst11080895 |
| Journal | Crystals |
| Issue Number | 8 |
| Volume Number | 11 |
| Language | English |
| Publisher | MDPI |
| Publisher Date | 2021-07-30 |
| Access Restriction | Open |
| Subject Keyword | Crystals Electrochemistry Tof Neutron Powder Diffraction Prussian Blue K+ Diffusion Coefficient Potassium-ion Battery |
| Content Type | Text |
| Resource Type | Article |
