In situ evaluation of mechanical and electrochemical degradation in silicon negative electrode for lithium-ion secondary batteries

Silicon is a promising anode material for lithium-ion battery application due to its high specific capacity. Unfortunately, silicon undergoes a volume expansion of 300~400% full lithiation and suffers from severe capacity fade, which limit its successful application in commercial cells. In this study, we used in situ acoustic emission and laser microscope observation method for detecting the volume change in silicon negative electrodes. It was shown that the long-term performance of the silicon negative electrode was dictated by its spallation during the discharge steps, while only the first lithiation caused its delamination and spoliation in the charge step. This strongly indicates that the energy of emission, and hence the amount of damage, is related to capacity loss. This study demonstrate that AE is a powerful tool to survey the real-time mechanical damage and electrochemical degradation in the electrode.