Comment by vel0city

IIRC it is the efficiency of the chemical process in the battery that is affected by cold temperatures. Different chemistries are affected differently.

This is a part of the reason why EVs will actually spend energy to warm up their battery packs in the cold, spending the energy to warm it up early will lead to better efficiency for the rest of the drive. Another reason why it's better to condition the car plugged in before starting a trip in the cold; the battery is already in its optimal temperature range.