Fundamentals in lithium ion batteries: effect of surface modification on the bulk process

Fabio La Mantia 

Ruhr-Universität Bochum, Anal. Chem. - Elektroanalytik & Sensorik (ELAN), Universitätsstr. 150, Bochum 44780, Germany

Abstract

Lithium-ion batteries are now used in a wide range of applications, particularly in connection with portable electronic devices. The wide interest and application range is due to the high power and energy density of such a system, as well as its life time. The challenge of using these systems in larger applications such as for personal or public transportation requires improvements in energy and power density, and also cycle life. This challenge cannot be achieved without a proper understanding of the surface phenomena that occur at the electrolyte/active material interface.

Although the intercalation reaction, which ensures the storage of energy in lithium-ion batteries, is a bulk process, it has been observed and demonstrated that surface modifications of the bare active materials can influence strongly the coulombic efficiency of the ion storage and the cycle life of the battery itself. Moreover, during the charge and discharge processes, the active materials in the battery, and also the conductive additives, are subjected to surface modification, triggered by the oxidation or reduction of the components contained in the organic electrolyte. The oxidation and reduction products, that form the solid electrolyte interphase (SEI) between the active material and the electrolyte, are studied by differential electrochemical mass spectrometry (DEMS) and electrochemical impedance spectroscopy (EIS).

An overview on the fundamentals of the intercalation/deintercalation process in lithium-ion batteries will be given, with particular focus on the modifications that occur on the surface of carbonaceous materials and lithium metal oxides, due to their interactions with the organic electrolyte (ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate). The effect of surface modification on the SEI and on the performance of the lithium-ion battery will be addressed.
 

Presentation: Tutorial lectore at SMCBS'2011 International Workshop, by Fabio La Mantia
See On-line Journal of SMCBS'2011 International Workshop

Submitted: 2011-08-31 16:29
Revised:   2011-09-01 10:17