Crystallographic structural changes in a commercial 5 Ah prismatic graphite–NMC battery were investigated during its operation using energy-dispersive X-ray diffraction. The characteristic diffraction peaks for the anode and cathode were identified, and their peak positions were linked to the charge–discharge cycle of the battery. The edge of the negative terminal of battery was shown to undergo irregular cycling behavior. Stresses developed at the battery layer interfaces were proposed to be the source for this deterioration, which limits the lifetime of the battery. The effect of pulse discharge on strain in cathode has also been studied.