In winter, the driving range of electric vehicles is significantly less than what manufacturers claim, sometimes by more than a third. Why is this?
This has to do with the principle of electric vehicle batteries. When an electric vehicle is parked outdoors in winter, the low temperature will directly affect the activity of the lithium battery. To restore the battery activity, electricity is needed to heat the battery and restore its temperature. This consumed electricity is the part of the range that is "reduced".
Generally speaking, the vast majority of electric vehicles and even electronic digital products on the market today use lithium-ion batteries, also known as lithium batteries. Common lithium batteries for electric vehicles are mainly lithium iron phosphate, lithium manganese oxide, and ternary lithium batteries.
Like other batteries, lithium-ion batteries have positive and negative electrodes. All lithium ions are stored at the positive electrode, while the negative electrode is made of graphite (carbon). Between the positive and negative electrodes are an 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. Lithium-ion batteries provide the electrical energy needed to operate various devices, including electric vehicles, through this discharge process.
In low-temperature environments, the reduced driving range of electric vehicles is primarily due to the impact of extremely low temperatures on the activity of lithium compounds. Currently, the most common lithium-ion battery compound is lithium iron phosphate, with others including lithium manganese oxide. The activity of these compounds at different temperatures determines the driving range of electric vehicle lithium-ion batteries at those temperatures.
For example, the most common lithium iron phosphate has excellent high-temperature resistance, thus exhibiting the best discharge capacity in the spring and summer when temperatures are between 20 and 40 degrees Celsius. However, in the northern winter, as temperatures drop, its activity gradually decreases, and its discharge capacity also gradually diminishes. Especially in the low-temperature environments common in Northeast China, such as -20 degrees Celsius, the capacity can even approach 50%.
The reason why the driving range of electric vehicles drops sharply in winter is now quite clear. Low temperatures significantly impact the activity of both the positive and negative electrodes of lithium batteries, thus the driving range of electric vehicles is obviously not as good as in other seasons.
To improve the activity of elements within lithium batteries, the battery temperature needs to be restored to its optimal operating temperature. Therefore, electric vehicle manufacturers take measures to "keep the temperature" of lithium batteries inside the vehicle.
In short, if an electric vehicle is parked outdoors in winter or in a low-temperature environment for a long time, the low temperature will directly affect the activity of the lithium battery. To restore the battery activity, electricity is needed to heat the battery and restore its temperature.
