Quantitative studies on thermal stability of a FeF₃ cathode in methyl difluoroacetate-based electrolyte for Li-ion batteries

The thermal behaviors of FeF₃ cathode in 1 mol dm^-3 LiPF₆/methyl difluoroacetate (MFA) electrolyte are quantitatively investigated by differential scanning calorimetry. MFA-based electrolyte shows great thermal stability without heat generation up to 500 C. The cycled electrodes are studied and find to become more thermally stable after lithiation. Furthermore, the lithiated electrode shows a superior thermal stability in the electrolyte compared to the delithiated electrode. Although the heat generated by the mixtures of cycled electrodes and MFA-based electrolyte is larger, the lithiated and delithiated electrodes coexisted with MFA-based electrolyte are about 140 and 230 C higher than that of EC + DMC-based electrolyte, respectively. Therefore, the safety of FeF₃ battery is enhanced by using MFA-based electrolyte instead of EC + DMC-based electrolyte. Crown