Universal Renaissance Strategy of Metal Fluoride in Secondary Ion Batteries Enabled by Liquid Metal Gallium

All-solid-state alkali ion batteries represent a future trend in battery technology, as well as provide an opportunity for low-cost metal fluoride electrode materials, if certain intrinsic problems can be resolved. In this work, a liquid metal activation strategy is proposed in which liquid Ga elements are generated in situ and doped into the LiF crystal structure by introducing a small amount of GaF3. Benefiting from these two Ga states of existence, in which the liquid metal Ga can continuously maintain conformable ion/electron-transport networks, while doped Ga in the LiF crystal structure catalyzes Li-F splitting, the lithium-ion storage capacity of MnF2 significantly increases by 87%. A similar effect can be obtained in FeF3, where the sodium-ion storage capacity is enhanced by 33%. This universal strategy with few restrictions can be used to realize a complete renaissance of metal fluorides, as well as offer an opportunity for the new application of liquid metals in the field of energy storage.