Thermal Behavior of a C∕LiCoO[sub 2] Cell, Its Components, and Their Combinations and the Effects of Electrolyte Additives

Abstract

Thermal behavior of a Li-ion cell, its components, and their combination was quantitatively investigated by the differential scanning calorimetry to understand its thermal runaway mechanism. The electrolyte reduction by the anode, the electrolyte oxidation by the cathode, and the combustion reaction based on the released oxygen from the cathode, were found to be important as main exothermic factors. The released oxygen burned even the polyethylene separator. The coexistence of the anode and the cathode caused some excessive heat generation, which was explained by “the shuttle effect.” The effects of the typical three electrolyte additives were examined in the same manner. The differential scanning calorimetry results suggested that the cathode plays a very important role for the thermal stability of the whole cell, because the thermal behavior of the cells is closely related to that of the cathodes.