Lithium-ion (Li-ion) batteries widely used in electric vehicles (EVs) and hybrid electric vehicles 2 (HEVs) are insufficient for vehicle use after they have degraded to 70 to 80 percent of their original capacity. 3 Battery lifespan is one of the largest considerations when designing battery packs for EVs/HEVs. Aging 4 mechanisms, such as metal dissolution, growth of the passivated surface film layer on the electrodes, and loss of 5 both recyclable lithium ions, affect the longevity of the lithium ion battery at high-temperature operations. Even 6 vehicle maneuvers at low temperatures (T<0°C) contribute to battery lifetime degradation, owing to the anode 7 electrode vulnerability to other degradation mechanisms like lithium plating. Nowadays, only few battery 8 thermal managements have been properly considering with low-temperature degradation. This is due to the 9 lack of studies on aging of Li-ion batteries at sub-zero temperature. This paper investigates how load cycle and 10 calendar life properties affect the lifetime and aging processes of Li-ion cells at low temperatures. Accelerated 11 aging tests were used to determine the effect of the ambient temperature on the performance of three 100Ah 12 LiFeMnP04 lithium-ion cells. Two of them were aged through a normalized driving cycle at two temperature 13 tests (-20°C and 25°C). The calendar test was carried out on one single battery at-20°C and mid-range of state-14 of-charge (SOC) (50%). Their capacities were continuously measured every two or three days. An aging model 15 is developed and added to a preliminary single cell electro-thermal model to establish in future works a thermal 16 strategy capable of predicting how the cell ages. This aging model was then validated by comparing its 17 predictions with the aging data obtained from a cycling test at 0°C.

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