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Rate dependence of the reaction mechanism in olivine NaFePO 4 Na‐ion cathode material
Author(s) -
Saurel Damien,
Galceran Montserrat,
Reynaud Marine,
Anne Henri,
CasasCabanas Montse
Publication year - 2018
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.4078
Subject(s) - olivine , cathode , ion , cycling , synchrotron , phase (matter) , materials science , analytical chemistry (journal) , kinetics , thermodynamics , chemistry , chemical physics , mineralogy , physics , organic chemistry , quantum mechanics , archaeology , chromatography , nuclear physics , history
Summary When electrode materials are driven away from equilibrium conditions, significant differences occur in their (dis)charge mechanism. In this paper, the changes in the phase transformations of the olivine NaFePO 4 are examined as a function of the cycling rate from the thorough analyses of both the voltage‐composition profiles of galvanostatic cycling, and operando laboratory and synchrotron X‐ray diffraction experiments. While the charge mechanism remains unchanged at all C‐rates, high cycling rates enable to unveil 2 concomitant biphasic reactions appearing as a 3‐phase state at lower rates. This finding allows rationalising the asymmetries observed at low rates, which are rooted in different reaction kinetics.