Abstract :
[en] Tin based intermetallic compounds proposed as negative electrode materials for Li-ion
batteries not only suffer from capacity fade during cycling due to volume variations but also
from aging phenomena in lithiated states. By using FeSn2 as a model compound, we propose
an analysis of this process by combining electrochemical potential measurements, 119Sn and
57Fe Mössbauer spectroscopies, magnetic measurements and impedance spectroscopy. We
show that the Fe/Li7Sn2 composite obtained at the end of the first discharge is progressively
transformed during the aging process occurring within the electrochemical cell in open circuit
condition. The Fe nanoparticles are stable while the Li7Sn2 nanoparticles are progressively
delithiated with time leading to Sn-rich LixSn nano-alloys without observable back reaction
with Fe. The deinserted lithium atoms react with the electrolyte and modify the surface
electrode interphase (SEI) by increasing its thickness and/or decreasing its porosity
chamas, mohamad; Southwest Petroleum University,
Tang, Junlei; Southwest Petroleum University,
Sougrati, Moulay Tahar; Université de Montpellier
Stefania, Panero; Universita di Roma « La Sapienza »
Pierre-Emmanuel, Lippens; Université de Montpellier
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