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Lithium (Li) concentration-dependent mechanical properties are crucial to the performance and durability of lithium ion batteries. Here, we report an in situ measurement of the evolution of elastic modulus and partial molar volume of commercial graphite electrodes. A bending model is developed to analyze the relationship between large curvature changes and materials properties. The curvature changes of the electrode are captured using a CCD camera during electrochemical cycling. Composite graphite electrodes with different thickness ratios are chosen as the working electrode. The modulus and partial molar volume are extracted which are both associated with the stress evolution of electrodes. The results show that the elastic modulus increases during the second lithiation process, while the partial molar volume shows a stage change corresponding to the phase change of graphite materials. These results are important for the mechanical modeling and provide basic information for the commercial graphite electrodes. Image 1 • Lithium concentration-dependent mechanical properties were measured in situ. • A mechanics model was developed to analyze the curvature deformation of electrodes. • Elastic modulus and partial molar volume of the commercial graphite electrode were reported. [ABSTRACT FROM AUTHOR]

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. Image 107001 [ABSTRACT FROM AUTHOR]