Title
Switching between solid solution and two-phase regimes in the <tex>$Li_{1-x}Fe_{1-y}Mn_{y}PO_{4}$</tex> cathode materials during lithium (de)insertion : combined PITT, in situ XRPD and electron diffraction tomography study Switching between solid solution and two-phase regimes in the <tex>$Li_{1-x}Fe_{1-y}Mn_{y}PO_{4}$</tex> cathode materials during lithium (de)insertion : combined PITT, in situ XRPD and electron diffraction tomography study
Author
Faculty/Department
Faculty of Sciences. Physics
Publication type
article
Publication
London ,
Subject
Physics
Chemistry
Source (journal)
Electrochimica acta. - London
Volume/pages
191(2016) , p. 149-157
ISSN
0013-4686
ISI
000371143200018
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
The electrochemical properties and phase transformations during (de)insertion of Li+ in LiFePO4, LiFe0.9Mn0.1PO4 and LiFe0.5Mn0.5PO4 are studied by means of galvanostatic cycling, potential intermittent titration technique (PITT) and in situ X-ray powder diffraction. Different modes of switching between the solid solution and two-phase regimes are revealed which are influenced by the Mn content in Li1-xFe1-yMnyPO4. Additionally, an increase in electrochemical capacity with the Mn content is observed at high rates of galvanostatic cycling (10C, 20C), which is in good agreement with the numerically estimated contribution of the solid solution mechanism determined from PITT data. The observed asymmetric behavior of the phase transformations in Li1-xFe0.5Mn0.5PO4 during charge and discharge is discussed. For the first time, the crystal structures of electrochemically deintercalated Li1-xFe0.5Mn0.5PO4 with different Li content LiFe0.5Mn0.5PO4, Li0.5Fe0.5Mn0.5PO4 and Li0.1Fe0.5Mn0.5PO4 are refined, including the occupancy factors of the Li position. This refinement is done using electron diffraction tomography data. The crystallographic analyses of Li1-xFe0.5Mn0.5PO4 reveal that at x = 0.5 and 0.9 the structure retains the Pnma symmetry and the main motif of the pristine x = 0 structure without noticeable short range order effects.
Full text (open access)
https://repository.uantwerpen.be/docman/irua/4128b4/131911.pdf
E-info
https://repository.uantwerpen.be/docman/iruaauth/d7c76e/131911.pdf
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