Fluorine is known to be a key element for various components of batteries since current electrolytes rely on Li-ion salts having fluorinated ions and electrode binders are mainly based on fluorinated polymers. Metal fluorides or mixed anion metal fluorides (mainly oxyfluorides) have also gained a substantial interest as active materials for the electrode redox reactions. In this review, metal fluorides for cathodes are considered; they are listed according to the dimensionality of the metal fluoride subnetwork. The synthesis conditions and the crystal structures are described; the electrochemical properties are briefly indicated, and the nature of the electron transport agent is noted. We stress the crucial importance of the elaboration processes to induce the presence of cation disorders, of anion substitutions (mainly F–/O2- or F–/OH–) or vacancies. Finally, we show that an accurate structural characterization is a key step to enable enhanced material performances to overcome several lasting roadblocks, namely the large irreversible capacity and poor energy efficiency that are frequently encountered.
Fluorinated materials as positive electrodes for Li- and Na-ion batteries, at http://fluoridealert.org/wp-content/uploads/lemoine-2022.supplementary-info.pdf
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.chemrev.2c00247.
Tables gathering main electrochemical performances of fluorinated materials as positive electrodes in LIB and NIB configurations with their synthesis methods and the corresponding morphological characteristics (PDF)
All crystal structure projections were realized with Diamond software (Diamond – Crystal and Molecular Structure Visualization; Crystal Impact – Dr. H. Putz and Dr. K. Brandenburg GbR, Kreuzherrenstrasse 102, 53227 Bonn, Germany; http://www.crystalimpact.com/diamond). A list of fluoride compounds, listed by the X/M ratio (X = ligands linked to the metals M), has been created. Crystallographic data and crystal chemistry details are given, together with links to Diamond files for the structure representations and to the CIF files. This database can be downloaded, free of charge, at the following address: http://www.reseau-fluor.fr/en/angressources/telechargements.
*Original abstract online at https://pubs.acs.org/doi/10.1021/acs.chemrev.2c00247