Revisiting Conversion Reaction Mechanisms in Lithium Batteries: Lithiation-Driven Topotactic Transformation in FeF2
- Brookhaven National Lab. (BNL), Upton, NY (United States). Sustainable Energy Technologies Dept.
- Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Condensed Matter Physics and Materials Science
- Univ. of Wisconsin, Eau Claire, WI (United States). Materials Science & Engineering
- Univ. College Cork, Cork (Ireland). School of Chemistry and the Tyndall National Inst.; Trinity College Dublin, Dublin (Ireland)
- Rutgers Univ., Piscataway, NJ (United States). Dept. of Materials Science and Engineering
- Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN); Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Materials Science and Engineering
Intercalation-type electrodes have now been commonly employed in today’s batteries as such materials are capable of storing and releasing lithium reversibly via topotactic transformation, conducive to small structural change, but they have limited interstitial sites to hold Li. In contrast, conversion electrodes feature high Li-storage capacity, but often undergo large structural change during (de)lithiation, resulting in cycling instability. One exception is iron fluoride (FeF2), a conversion-type cathode that exhibits both high capacity and high cycling stability. Herein, we report a lithiation-driven topotactic transformation in a single crystal of FeF2, unveiled by in situ visualization of the spatial and crystallographic correlation between the parent and converted phases. Specifically, conversion in FeF2 resembles the intercalation process but involves transport of both Li+ and Fe2+ ions within the F-anion array, leading to formation of Fe preferentially along specific crystallographic orientations of FeF2. Throughout the process, the F-anion framework is retained, creating a checkerboard-like structure, within which the volume change is largely compensated, thereby enabling the high cyclability in FeF2. Lastly, findings from this study, with unique insights into conversion reaction mechanisms, may help to pave the way for designing conversion-type electrodes for the next-generation high energy lithium batteries.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1492791
- Report Number(s):
- BNL-210929-2019-JAAM
- Journal Information:
- Journal of the American Chemical Society, Vol. 140, Issue 51; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Using nanoconfinement to inhibit the degradation pathways of conversion-metal oxide anodes for highly stable fast-charging Li-ion batteries
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journal | January 2020 |
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