Li-ion electrochemical cells have shown marked improvements in capacity retention as well as safety using additives to polycarbonate electrolyte solutions.  In a similar approach aimed at fundamental understanding, we have doped electrolyte solutions with heavy alkali cations (Rb+ and Cs+) with the goal of incorporating these cations into the surface films formed on both the cathode and anode active material known as the solid electrolyte interphase (SEI).  These cations were chosen for their similar chemical reactivity as Li+ and surface selectivity due to their much larger ionic radii than Li+.  Chemical and local structure information is tracked using micro-probe Raman, X-ray photoelectron, and X-ray absorption spectroscopy as a function of electrochemical cycling.  Findings suggest this approach could be a promising method to track the formation, growth, and chemistry of the SEI.

Capturing the interface in Li-ion cells with heavy alkali dopants: Raman and X-ray techniques

246th National Meeting (2013)

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