<p>The insertion and extraction of lithium ions in active materials lead to significant volumetric deformation, resulting in stresses that drive the mechanical degradation of these materials. This accumulation of mechanical degradation ultimately leads to mechanical failure in lithium-ion batteries (LIB). This paper summarizes the experimental characterization techniques used to observe the mechanical degradation of lithium battery cells, electrodes, and particles across macro, micro, and nano scales. Additionally, the mechanical failure model for LIB that spans from the microscopic to the macroscopic scale has been outlined. Finally, we analyze the current challenges and opportunities, including the standardization of battery measurements, the quantification of mechanical failures, and the correlation between mechanical failures and electrochemical performance.</p>