Role of solution structure in solid electrolyte interphase formation on graphite with LiPF6 in propylene carbonate
Date of Original Version
An investigation of the interrelationship of cycling performance, solution structure, and electrode surface film structure has been conducted for electrolytes composed of different concentrations of LiPF6 in propylene carbonate (PC) with a binder-free (BF) graphite electrode. Varying the concentration of LiPF6 changes the solution structure, altering the predominant mechanism of electrolyte reduction at the electrode interface. The change in mechanism results in a change in the structure of the solid electrolyte interface (SEI) and the reversible cycling of the cell. At low concentrations of LiPF6 in PC (1.2 M), electrochemical cycling and cyclic voltammetry (CV) of BF graphite electrodes reveal continuous electrolyte reduction and no lithiation/delithiation of the graphite. The solution structure is dominated by solvent-separated ion pairs (Li+(PC) 4//PF6-), and the primary reduction product of the electrolyte is lithium propylene dicarbonate (LPDC). At high concentrations of LiPF6 in PC (3.0-3.5 M), electrochemical cycling and CV reveal reversible lithiation/delithiation of the graphite electrode. The solution structure is dominated by contact ion pairs (Li+(PC) 3PF6-), and the primary reduction product of the electrolyte is LiF. © 2013 American Chemical Society.
Journal of Physical Chemistry C
Nie, Mengyun, Daniel P. Abraham, Daniel M. Seo, Yanjing Chen, Arijit Bose, and Brett L. Lucht. "Role of solution structure in solid electrolyte interphase formation on graphite with LiPF6 in propylene carbonate." Journal of Physical Chemistry C 117, 48 (2013): 25381-25389. doi:10.1021/jp409765w.