Widespread developments in the manufacture of electric vehicles have been accompanied by higher requirements for their safety. As an important test for the mechanical safety of power batteries, the nail penetration test needs further study in order to explore the impact of the puncture process on the internal structure, so as to evaluate the safety of power batteries. In this paper, by combining multi-methods including computed tomography, mechanics analysis and simulation, we characterize the evolution of the battery's internal structure. Furthermore, through dismantling analysis, the evolution of battery materials during nail penetration is also explored.