Life prediction of lithium thionyl chloride batteries based on the pulse load test and accelerated degradation test

Abstract The lithium thionyl chloride (Li/SOCl 2 ) battery is widely used as an important long‐life backup power source. Accurate battery life prediction is essential to ensure the reliability of equipment and systems. In this paper, a novel method was proposed for the life prediction of Li/SOCl 2 batteries based on the pulse load test and accelerated degradation test (ADT). The proposed pulse load test method can estimate the primary battery capacity accurately and nondestructively, which solves the challenge of quantifying degradation due to unknown initial values. Furthermore, we noticed a new phenomenon that capacity loss was affected by electrolyte fluidity, and unexpected capacity loss was observed for batteries at different discharge angles. By analyzing the mechanism of this phenomenon, we avoided serious capacity measurement errors in the 24‐week ADT. A life prediction model with a satisfactory ability to approximate the measured data was established depending on the exponential influence of time and temperature on capacity degradation.