Effect of thermal environments on fast charging Li-ion batteries

Battery thermal management systems (BTMSs) are expected to keep the battery temperature at a moderate level (similar to 30 degrees C) to minimize the thermally exacerbated degradation. However, during fast charging, a strong cooling system is required to restrict the temperature rise of Li-ion batteries (LiBs), which significantly increases the cost and weight of battery packs, and induces a large temperature variation inside the battery. In this work we find that all these drawbacks could be relieved by allowing LiBs to charge at higher temperatures. Since the fast charging of a LiB only takes a tiny fraction of its lifetime, the aging rate is limited even at a charging temperature of 60 degrees C. Three types of thermal environments are proposed: kept constant at 30 degrees C, preheated to 60 degrees C, and adiabatic fast charging. With an experimentally validated electrochemical-thermal (ECT) coupled model, we explore the interplay between thermal management and the fast-charging performance. It is found that a gradually increasing temperature profile is the best option to balance the lithium plating and thermal management of the battery. Combining adiabatic fast charging with a preheating step, we can achieve minimal cooling need, perfect temperature uniformity within a battery, and fast-charging capability simultaneously.

Automated summary

This study suggests that allowing Li-ion batteries to charge at higher temperatures can alleviate the issues of increased cost and weight caused by strong cooling systems during fast charging. By using an experimentally validated model, it is shown that a gradually increasing temperature profile can achieve a balance between fast charging and thermal management of the battery.