Understanding the Fluorination of Disordered Rocksalt Cathodes through Rational Exploration of Synthesis Pathways

We have designed and tested several synthesis routes targeting a highly fluorinated disordered rocksalt (DRX) cathode, Li1.2Mn0.4Ti0.4O1.6F0.4, with each route rationalized by thermochemical analysis. Precursor combinations were screened to raise the F chemical potential avoid formation of LiF, which inhibits fluorination targeted DRX phase. MnF2 was used as reactive source F, Li6MnO4, LiMnO2, Li2Mn0.33Ti0.66O3 alternative Li sources. Each procedure monitored using multi-modal suite characterization techniques including X-ray diffraction, nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry. From resulting data, we advance understanding oxyfluoride outlining key factors limiting solubility. At low temperatures, consistently reacts form LiF an intermediate phase, thereby trapping in strong Li–F bonds. can react Li2TiO3 lithiated (Li3TiO3F); however, MnO is not easily incorporated into this Although higher temperatures typically increase solubility, volatility above its melting point (848 °C) Based on these findings, metastable are suggested for future work fluorination.