Research on the Detection of Capacity and Capacity Fading of Li-Ion Battery of Electric Vehicles Based on Tomographic Imaging

Abstract

It is difficult for us to use the conventional detecting method to obtain the capacity and fading of electric vehicle Li-ion battery in real-time, nondestructively and quickly. To solve the problem, the lithium iron phosphate (LFP) batteries are regarded as the research objects to study the relationship between their electrochemical performance and the structural parameters of theirs active materials based on Faraday's law, which reflects the relationship between capacity of a battery and the mass of its active materials. A capacity and fading detecting method of Li-ion battery based on tomographic imaging is proposed. A capacity and fading detecting system of Li-ion battery is established to carry out experiments with a batch of LFP batteries. The experimental results show that the actual capacity of a Li-ion battery is related to the total number of pixels of the active materials in its cross-sectional image, and the loss of its negative active materials is more than that of its positive active materials, when its capacity loses. Compared with the conventional methods, this method is superior in terms of being real-time, nondestructive and quick.