Rights statement: This is an author-created, un-copyedited version of an article accepted for publication/published in Journal of The Electrochemical Society. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.1149/1945-7111/ac4544
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - New Insight into Li+Dynamics in Lithium Bimetal Phosphate
AU - Savignac, L.
AU - Griffin, J.M.
AU - Schougaard, S.B.
N1 - This is an author-created, un-copyedited version of an article accepted for publication/published in Journal of The Electrochemical Society. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.1149/1945-7111/ac4544
PY - 2022/1/12
Y1 - 2022/1/12
N2 - Substitution of iron by other transition metals within the remarkably stable olivine framework is of interest considering the expected gain in energy density. However, manganese rich olivine materials suffer from sluggish redox kinetics, leading to electrochemical performances at high current densities which are below expectations. The source of the kinetic limitations is not clear, with multiple processes having been proposed, including low bulk electronic conductivity, structural instability of Mn3+ and a phase transition mechanism. This study employed 7Li MAS NMR relaxation techniques to indirectly probe Li+ dynamics using various stoichiometry of chemically prepared Li x MnyFe1-yPO4 (0 ≤ (x, y) ≤ 1). Focusing on the particle level, the aim was to understand how the different crystal phases, alongside the Mn structural contribution, influence Li+ transport at each stage of the oxidation process. Significantly, the formation of an olivine solid solution with vacancies within this progression gave rise to a faster 7Li transverse relaxation derived from superior Li+ motion.
AB - Substitution of iron by other transition metals within the remarkably stable olivine framework is of interest considering the expected gain in energy density. However, manganese rich olivine materials suffer from sluggish redox kinetics, leading to electrochemical performances at high current densities which are below expectations. The source of the kinetic limitations is not clear, with multiple processes having been proposed, including low bulk electronic conductivity, structural instability of Mn3+ and a phase transition mechanism. This study employed 7Li MAS NMR relaxation techniques to indirectly probe Li+ dynamics using various stoichiometry of chemically prepared Li x MnyFe1-yPO4 (0 ≤ (x, y) ≤ 1). Focusing on the particle level, the aim was to understand how the different crystal phases, alongside the Mn structural contribution, influence Li+ transport at each stage of the oxidation process. Significantly, the formation of an olivine solid solution with vacancies within this progression gave rise to a faster 7Li transverse relaxation derived from superior Li+ motion.
KW - Iron compounds
KW - Lithium compounds
KW - Manganese compounds
KW - Olivine
KW - Electrochemical performance
KW - Electronic conductivity
KW - Energy density
KW - High current densities
KW - Kinetic limitations
KW - Li +
KW - Multiple process
KW - Olivine materials
KW - Redox kinetics
KW - Structural instability
KW - Transition metals
U2 - 10.1149/1945-7111/ac4544
DO - 10.1149/1945-7111/ac4544
M3 - Journal article
VL - 169
JO - Journal of The Electrochemical Society
JF - Journal of The Electrochemical Society
SN - 0013-4651
IS - 1
M1 - 010510
ER -