Temperature and battery life

Temperature is one of the strongest influences on battery ageing. Lithium-ion cells tend to age slowest around room temperature; heat accelerates SEI growth, while cold raises the risk of lithium plating during charging.

An ageing minimum near room temperature

Research on commercial cells found that the ageing rate is lowest around 25 °C, with different mechanisms dominating on either side. Above that range, SEI growth and other side reactions speed up with temperature. Below it, especially during charging, lithium plating on the anode becomes the main concern.

Work on LFP cells reached a similar picture: temperature-dependent SEI growth dominates when warm, while plating takes over at low temperatures and higher charging currents. The exact location of the minimum and how steeply ageing rises on either side differ by chemistry and cell design.

Heat: steady, cumulative stress

Calendar ageing follows the Arrhenius relationship: reaction rates rise with temperature, and the rise becomes steeper as it gets hotter. A battery that spends many hours warm, for example parked in the sun in a hot climate, ages faster than an identical battery kept cool. Fleet telematics data associates hot climates with faster average capacity decline.

Heat and high SOC reinforce each other. A full battery in a hot parking spot combines two calendar stressors, so in warm periods time at high SOC deserves extra attention.

Cold: mostly a charging issue

Cold itself does relatively little harm to a parked battery; it mainly slows the chemistry down. The risk appears when charging a cold battery, because lithium cannot enter the graphite quickly enough and may deposit on the surface instead. Low-temperature studies confirm that charging in the cold can cause substantial extra ageing.

This is why the BMS limits charging power when the pack is cold, and why preconditioning before winter fast charging is useful. Slow AC charging in the cold is generally less of a concern because the current is low.

Cell temperature is not air temperature

What matters is the temperature of the cells, which can differ considerably from the outside air. Thermal management, driving, charging and time of day all affect it. Voltgevity estimates pack temperature from your climate, parking situation and the vehicle's thermal management, and uses that estimate in both the calendar and the cycle ageing calculations.

Key takeaways

Ageing tends to be slowest near room temperature, around 25 °C.
Heat accelerates calendar ageing and amplifies the stress of high SOC.
Cold matters mainly during charging, when it raises lithium plating risk.
Cell temperature depends on climate, parking and thermal management, not just on outside air.