Film formation in LiBOB-containing electrolytes

Lithium bis(oxalato)borate (LiBOB), a new electrolyte salt for lithium batteries, is actively involved in the formation of the solid electrolyte interphase (SEI) at the anode. Part of this formation is an irreversible reductive reaction taking place at potentials of around 1.75 V versus Li/Li+ and contributing to the irreversible capacity of anode materials in the first cycle. Cyclic voltammetry has been performed on several carbon materials as well as on Li4Ti5O12 and pre-treated glassy carbon electrodes in order to achieve a better understanding of the underlying processes. It is found that the intensity of the 1.75 V peak depends on the BET specific surface area and the surface chemistry of the active material and increases with the amount of oxygen-containing surface functionalities. It is not specific to carbonaceous materials but is also observed on carbon-free anodes like Li4Ti5O12. In addition, the effect of several potential impurities and of film-forming additives on the filming behaviour of LiBOB-containing electrolytes has been investigated. (c) 2005 Elsevier B.V. All rights reserved.