Hosted by: Ignace Jarrige

An energy storage paradigm orthogonal to Li-ion battery chemistries can be conceptualized by employing anions as the primary charge carriers. F-ion conversion chemistries show promise but have limited cyclability as a result of the significant change in volume of active electrodes upon metal−metal fluoride interconversion. In contrast, the exploration of insertion chemistries has been stymied by the lack of hosts amenable to reversible F-ion insertion at room temperature. In this study, we showed reversible and homogeneous topochemical insertion/deinsertion and bulk diffusion of F ions within the one-dimensional tunnels of sub-micrometer-sized FeSb2O4 particles at room temperature. The insertion of F ions is evidenced by formal oxidation of the iron centers from Fe2+ to Fe3+ with a lattice volume contraction of