The driving range of electric vehicles with lithium-ion batteries decreases in winter for several reasons. First, it is related to the internal electrodes and electrolyte of the battery. For the power lithium batteries of electric vehicles, the activity of the positive electrode material decreases as the temperature drops. The electrochemical characteristics of the battery will cause the battery activity to decrease rapidly, resulting in an increase in the internal resistance of the battery.
Inside a lithium-ion battery, all lithium ions are stored at the positive electrode, while the negative electrode is composed of graphite (carbon). Between the positive and negative electrodes lies the electrolyte and a separator. The discharge process of a lithium-ion battery is the movement of lithium ions from the negative electrode to the positive electrode, and this discharge provides the electrical energy needed for the operation of electric vehicles.
As temperatures drop, the charging and discharging process slows down. Consequently, the discharge current decreases, and the battery capacity also decreases. While lithium-ion batteries are rated for operating temperatures of 0-40°C, performance actually degrades to some extent below 25°C: battery capacity decreases, discharge speed slows, and battery output power is reduced.
