Comparative investigation of the impact of fast charging at low temperature on commercial Li-ion cells

Abstract

This study addresses the challenges associated with lithium-ion battery fast charging at a low temperature. A number of commercially available 18650 Li-ion cells were selected and comparatively tested for fast charging at different temperatures. Whereas a majority of the cells were able to fast charge efficiently at 23 °C, their fast charging capabilities decreased significantly at lower temperatures. Interestingly, the five best cells included energy, balanced and power cells. The best cells were repeatedly charged at a 2C rate for 300 cycles, leading to varying performance profiles, strongly depending on the temperature. A post-mortem analysis was carried out for the cells fast charged at −10 °C to investigate the failure modes. Even though several degradation modes were observed, the main cause for performance decay and cell failure was a loss of lithium inventory caused by an abnormal growth of the anode solid electrolyte interphase (SEI). Lithium plating and graphite exfoliation were determined to be the main causes for SEI growth. Finally, a comparative analysis was performed on the battery component choices and manufacturing parameters, which provides guidance towards the manufacturing of cells more capable of sustaining repeated fast charges at ambient and low temperatures.