SOH modelling of Li-Ion coin cells subjected to varying C-rates, depths of charge, operating temperatures and custom charge profiles

Portable consumer electronics devices continue to be one of electronics high-demand items, with rising interest in such products recently. Li-Ion batteries are the most popular power source choice of these products owing to a combination of high specific energy and specific power. In consumer electronics products, these batteries are generally employed in their coin form factor in biomedical devices, sensors, wireless earbuds, etc. These developments have boosted the research effort on Li-Ion power sources, and a major part of this effort is the prognostics of Li-Ion battery state of health (SOH) and predicting its remaining useful life. In addition to the common operation and environmental parameters such as the C-rate, the surrounding temperature and the depth of charge, additional parameters such as custom charge profiles employed by products need to be considered while modelling battery SOH degradation. This study focuses on the development of a SOH estimation model for two types of Li-ion coin cells subjected to accelerated life testing along with varying C-rates, operating temperature and depths of charge. Moreover, a custom charge profile wherein the charging current supplied to the battery was modified throughout its life cycle depending upon its instantaneous capacity was experimented to see its effect on the SOH degradation rate. Finally, regression models, focusing on the relation between SOH degradation and battery use parameters was developed.