Gas Desorption Behavior of Graphite Anode in Lithium Ion Secondary Battery and its Effect on the Battery Performance

Abstract

As the anode material, natural graphite, polymer-coated natural graphite, carbon-coated natural graphite and artiˆcial graphite were employed. In order to examine the eŠect of solid electrolyte interface (SEI), these samples were exposed to the cycles of charge/discharge. The gas desorption behavior of these samples was investigated by using a technique of thermal desorption spectroscopy. The amount of desorbed gasses signiˆcantly increased after a charge/discharge cycle. The increase of the desorbed amount was associated with gas desorption from SEI formed in theˆrst cycle. The amount of desorbed gasses increases with an irreversible capacity in theˆrst charge/discharge cycle. The irreversible capacity of surface-coated graphite and artiˆcial graphite was lower than that of natural graphite. The surface coating resulted in the decrease of the amount of desorbed gasses and irreversible capacity. The atomic composition was measured by auger electron spectroscopy. Carbon, Oxygen, ‰uorine and phosphorus were observed after a charge/discharge cycle.