Real-time measurements of electro-mechanical coupled deformation and mechanical properties of commercial graphite electrodes

Abstract

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.