Evaluating bulk Nb2O2F3 for Li-battery electrode applications
2016 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 5, 3530-3535 p.Article in journal (Refereed) PublishedText
This investigation has the primary objective of elucidating the lithium intercalation process in the crystal structure of a new niobium oxyfluoride compound Nb2O2F3. The framework of the density functional theory was applied in a generalized gradient approximation together with the hybrid functional method. It is revealed that lithium atoms intercalate in this material in a maximum concentration of one Li atom per formula unit forming LiNb2O2F3. Moreover, octahedral positions in between the layers of Nb-O-F appear as the Li preferred occupancy resulting in a structural volume expansion of only 5%. Electronic structure evolution with the insertion of lithium displays a transformation from semi-conductor to metal when half of the lithium atoms are added. This transformation occurs due to a symmetry break induced by the transition from the + 8 to + 7 oxidation state of half of the Nb2 dimers. Then, after full lithiation the symmetry is recovered and the material becomes a semiconductor again with a band gap amounting to 1 eV. The evaluated average deintercalation potential reaches 1.29 V vs. Li/Li+ with activation energy for lithium ion migration of 0.79 eV. The computed low potential of the redox reaction Nb-2(8+) to Nb-2(7+) includes niobium oxyfluoride in the map of possible materials for the anode application of Li-ion batteries.
Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016. Vol. 18, no 5, 3530-3535 p.
IdentifiersURN: urn:nbn:se:kth:diva-183191DOI: 10.1039/c5cp06829kISI: 000369508100020PubMedID: 26751421ScopusID: 2-s2.0-84956939620OAI: oai:DiVA.org:kth-183191DiVA: diva2:908924
FunderSwedish Research CouncilStandUp
QC 201603032016-03-032016-03-032016-03-03Bibliographically approved