In lithium ion battery research numerous surface science techniques have been used to analyze the solid-electrolyte interphase (SEI) between battery electrodes and electrolyte however many of these techniques cannot be used <i>in situ</i> under anaerobic conditions.  To address this problem and to try and better understand the SEI we used a commercially available electrochemical quartz crystal microbalance with dissipation (EQCM-D) technique in an Argon glovebox to probe not only the mass of lithium insertion/deinsertion and electrolyte decomposition but also the viscoelastic properties of these layers as a function of potential.  The SEI between Sn anodes and Gen 2 electrolyte was investigated with and without additives of 10-20% fluoroethylene carbonate (FEC).  The results show that during the first discharge process from open circuit potential to 0.4 V the mass formed on the Sn electrode behaves in a rigid fashion (low dissipation values) until ~0.4 V where the layer starts to take on viscoelastic characteristics until the final potential of 0.01 V.  Increasing the concentration of FEC inhibits the amount of electrolyte decomposition based on the mass adsorbed to the Sn surface with the SEI layer becoming less stiff and more viscous as the potential approaches 0.01 V.  In a general sense this method and analysis should be relevant to others attempting to characterize electrodes and their corresponding interphases.

Using quartz crystal microbalance with dissipation (QCM-D) measurements to characterize <i>in situ</i> Li-ion battery solid-electrolyte interphases

251st National Meeting (2016)

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Using quartz crystal microbalance with dissipation (QCM-D) measurements to characterize in situ Li-ion battery solid-electrolyte interphases