Battery capacity degradation of new energy vehicles under low temperature

According to statistics, the sales of new energy vehicles in March this year, year-on-year growth rate of 100.9%, while the retail of traditional fuel vehicles fell by 15.0% year-on-year. However, there are still some concerns about new energy vehicles, including the problem of battery degradation at low temperatures, which should be considered by consumers.

According to the test, under the simulated low-speed urban road conditions, -7℃ outside temperature and 20~22℃ inside temperature, the actual range is less than half of the nominal range. The simulated conditions of the test are harsh, but more suitable for winter driving scenarios, which shows that in the winter low temperature environment, the actual range of new energy vehicles (especially pure electric vehicles) will be greatly reduced, which will also have a greater impact on the driver’s experience.

The lithium battery, for example, which is widely used in new energy vehicles, has five main structural parts: positive electrode, negative electrode, electrolyte, separator, shell and electrode leads. In the winter low temperature environment, the viscosity of the electrolyte increases or even partially solidified, and the compatibility between the negative electrode and the diaphragm deteriorates, resulting in a decrease in battery activity, battery capacity and charge and discharge efficiency, resulting in the attenuation of the battery of the new energy vehicle.

In order to cope with this problem, most car companies are committed to optimizing the battery management system (BMS), in the low temperature environment, part of the electricity into heat energy, heating the entire battery pack, to some extent to improve the problem of low temperature battery degradation. In winter, it is recommended that consumers get into the habit of turning on the heating and air conditioning before driving and charging, which can raise the temperature of the battery itself to get higher mileage and charging efficiency.