Performance and the Characteristics of Thermally Stressed Anodes in Lithium Ion Cells

Abstract

A new laboratory lithium ion cell in two electrode arrangement has been developed in order to apply in-situ short-term thermal stress tests to both electrodes. Cells were made from commercially available LiCoO2 cathodes, graphite anodes and electrolyte. A 60 s thermal stress was applied with different temperatures ranging from 100 to 250°C at the anode side after the cell formation and capacity tests. By comparison of the charge-discharge behavior of the cells before and after the thermal stress, capacity losses, increasing overvoltages and self-discharge have been observed as a function of the stress temperature. For detection of changes in the anode properties scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and computed tomography (CT) characterizations were used, and changes in the morphology and composition of the solid electrolyte interfaces (SEI) layer were observed.