Theoretical and experimental study on the interfacial adhesive properties of graphite electrodes in different charging and aging states

Abstract

The present study consists in the development of an analytical model and the performance of 180° peeling tests aimed at evaluating the interfacial adhesive properties of graphite electrodes of lithium–ion batteries in different charging/discharging states. In order to determine the interfacial peeling strength, uniaxial tensile tests were conducted and an analytical model was used to obtain the elastic modulus of copper foil and the graphite active layer in different charging/discharging states. Results of the application of the interfacial peeling strength analytical model indicate that the interfacial peeling strength between graphite active layer and current collector does not depend exclusively on the energy release rate but also on the strain energy stored in the collector as a consequence of the expansion of the active layer associated with the insertion within it of lithium ions. The results of the 180° peeling tests indicate that the interfacial peeling strength of the fully charged electrode is larger than the corresponding parameters measured in the fresh, soaked, and fully discharged electrodes. The predictions based on the analytical model and the experimental data collected on the interfacial peeling strength are in good agreement with each other.