Formation of the Graphite/Electrolyte Interface by Lithium Bis(oxalato)borate

Abstract

Solid electrolyte interface (SEI) formed on graphitic anode in electrolyte containing a salt, lithium bis(oxalato)borate (LiBOB), was investigated using electrochemical means, and an irreversible reduction process was found for LiBOB on graphitic anode at ca. 1.6 V vs. Li. To ascertain whether this process is responsible for the unique LiBOB property in stabilizing graphene structure against propylene carbonate (PC), we systematically interrupted the lithiation of graphitic anodes in LiBOB-electrolytes at a series of potentials and then tested the survivability of these preformed anodes in PC solution of LiPF 6 , an electrolyte composition known to exfoliate graphite materials readily. The results demonstrate that the formation of a functioning SEI is completed at potentials around 0.50 V vs. Li, and confirmed that BOB-anion plays a critical role in the effectiveness of the formed SEI to protect the graphene structure from exfoliation even in PC.