Impact of high-power charging on the durability and safety of lithium batteries used in long-range battery electric vehicles

Abstract

Battery electric vehicles with a range of more than 500 km are expected to become increasingly competitive in the future. The energy density of the currently available lithium batteries should be significantly increased to support the operation of such vehicles, and high-power charging is required to reduce the charging time. However, high-power charging may negatively affect the durability and safety of lithium batteries because of increased heat generation, capacity fading, and lithium plating, which can induce the risk of battery thermal runaway. Currently, there are no established boundary conditions for high-power charging or methods for evaluating its risks, especially in case of high-capacity lithium batteries. This study proposes a test procedure for examining the reaction characteristics of the capacity fading and thermal tolerance of lithium batteries that are subjected to high-power charging. Further, the migration characteristics of the temperature threshold of battery thermal runaway are investigated using the proposed procedure. The test results demonstrate that high-power charging significantly impacts the durability and thermal safety of the high-capacity lithium batteries. In particular, the capacity fading rate can reach up to 30% only after 100 charge cycles depending on the battery type. Furthermore, the thermal tolerance can decrease up to 40% by considering the change in the self-heating temperature as an indicator. Based on the study results, it can be concluded that the thermal management systems should be carefully designed to satisfy the high-power charging requirements. Otherwise, the high power charging only can be performed with limited range for battery electric cars with long all electric range.