A novel battery microscopic stress model towards state of health estimation of lithium-ion batteries

Abstract

The study of battery health is closely related to battery safety. Accurately describing the status changes inside the battery can effectively prevent battery safety problems. In this paper, a novel method based on internal battery stress is proposed to improve the accuracy of health status assessment of lithium batteries. The dynamic equilibrium relationship of microscopic stress in the battery is obtained through the material transfer relationship and particle diffusion equation inside the battery material particles. Based on the mapping relationship between fatigue strength and stress of battery materials, the evaluation and prediction of battery health status are completed. The validity of the model is verified by the measured lithium battery data. The results show that the maximum stresses are 9.5/12/16 MPa respectively in 5 %/50 %/100 % DOD cycles. When the battery is in a static state, the initial stress is −0.5Mpa caused by structural differences in different areas. The model can track the cycle life of the battery well, and the overall prediction error is kept within 3.5 %.The method demonstrates high performance.