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The Influence of PMS-Additive on the Electrode/Electrolyte Interfaces in LiFePO4/Graphite Li-Ion Batteries

K. C. Hogstrom ; S. Malmgren ; M. Hahlin ; H. Rensmo ; Frédéric Thébault (Institutionen för teknisk fysik) ; Patrik Johansson (Institutionen för teknisk fysik, Kondenserade materiens fysik) ; K. Edstrom
Journal of Physical Chemistry C (1932-7447). Vol. 117 (2013), 45, p. 23476-23486.
[Artikel, refereegranskad vetenskaplig]

The influence of a film-forming additive, propargyl methanesulfonate (PMS), on electrochemical performance and electrode/electrolyte interface composition of LiFePO4/graphite Li-ion batteries has been studied. Combined use of in-house X-ray photoelectron spectroscopy (XPS) and soft and hard X-ray photoelectron spectroscopy (PES) enabled nondestructive depth profiling at four different probing depths in the 2-50 nm range. Cells cycled with PMS and LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC) were compared to a reference sample cycled without PMS. In the first cycle, PMS cells showed a higher irreversible capacity, which is explained by formation of a thicker solid electrolyte interphase (SEI). After three cycles, the SET thicknesses were determined to be 19 and 25 nm for the reference and PMS samples, respectively. After the initial cycling, irreversible losses shown by the PMS cells were lower than those of the reference cell. This could be attributed to a different SET composition and lower differences in the amount of lithium between lithiated and delithiated electrodes for the PMS sample. It was suggested that PMS forms a triple-bonded radical on reduction, which further reacts with the electrolyte. The PMS additive was shown to influence the chemical composition at the positive electrode/electrolyte interface. Thicker interface layers with higher C-O and smaller LiF contributions were formed on LiFePO4 cycled with PMS.

Nyckelord: ray photoelectron-spectroscopy, surface-chemistry, electrochemical-behavior, functional electrolytes, graphite-electrodes, ethylene carbonate, thermal-stability, lithium, sei, mechanisms



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Denna post skapades 2013-12-17. Senast ändrad 2016-07-12.
CPL Pubid: 189439

 

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Institutioner (Chalmers)

Institutionen för teknisk fysik (1900-2015)
Institutionen för teknisk fysik, Kondenserade materiens fysik (1900-2015)

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Energi
Materialvetenskap
Transport
Materialteknik

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