Reversible Li-Intercalation through Oxygen Reactivity in Li-Rich Li-Fe-Te Oxide Materialsстатья
Статья опубликована в высокорейтинговом журнале
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 8 декабря 2015 г.
Аннотация:Lithium-rich oxides are a promising class of positive electrode materials for next generation lithium-ion batteries, and oxygen plays
a prominent role during electrochemical cycling either by forming peroxo-like species and/or by irreversibly forming oxygen gas
during first charge. Here, we present Li-Fe-Te-O materials which show a tremendous amount of oxygen gas release. This oxygen
release accounts for nearly all the capacity during the first charge and results in vacancies as seen by transmission electron microscopy.
There is no oxidation of either metal during charge but significant changes in their environments. These changes are particularly
extreme for tellurium. XRD and neutron powder diffraction both show limited changes during cycling and no appreciable change in
lattice parameters. A density functional theory study of this material is performed and demonstrates that the holes created on some
of the oxygen atoms upon oxidation are partially stabilized through the formation of shorter O-O bonds, i.e. (O2)n– species which
on further delithiation show a spontaneous O2 de-coordination from the cationic network and migration to the now empty lithium
layer. The rate limiting step during charge is undoubtedly the diffusion of oxygen either out along the lithium layer or via columns
of oxygen atoms.