Study on multimodal excitation infrared thermography for surface damage detection of lithium battery pole piece

The pole piece, as a key component of lithium-ion batteries (LIBs), is prone to the formation of defects such as scratches and pinholes during the manufacturing process, which poses significant risks to the safety of the batteries. To address this issue, we conducted a study on multimodal excitation infrared thermography (ME-IRT) method to identify defects on the surface of pole pieces, which includes pulse thermography (PT), lock-in thermography (LT), linear frequency modulation (LFM), and nonlinear frequency modulation (NFM) processing methods, and utilises an engineered diffuse reflector to eliminate the Gaussian characteristics of the heat source. Signal-to-noise ratio (SNR) was employed for the quantitative analysis of the detection results for different defects. The results show that the ME-IRT method can effectively suppresses background noise, yielding high-quality images that facilitate the detection of different pole piece defects. Compared to other ME-IRT methods, LFM demonstrated superior defects detection capability for the pole pieces. For all defects of the prepared specimen, the accuracy of size evaluation was greater than 90%. The study indicates that IRT method can effectively and reliably detect scratches and pinhole defects on the pole pieces.