Abstract: The present disclosure are directed to techniques for defect detection and identification inside batteries. In one aspect, a non-invasive method of identifying and labeling defects in a battery cell includes transmitting acoustic signals through a battery cell via one or more first transducers, receiving response signals in response to the acoustic signals at one or more second transducers, determining whether at least one feature of interest exists in the battery cell based on analyzing the response signals, performing an identification and labeling process on the at least one feature of interest to determine at least one defect in the battery cell, and outputting a result of the identification and labeling process.