Is endurance ability for lithium battery of electric vehicles very bad in winter?

Is endurance ability for lithium battery of electric vehicles very bad in winter?

After heavy snow, the wet and slippery roads in Beijing bring a lot of inconvenience to people's travel, but for pure electric car owners, inconvenience brought to daily use cars in winter is not only the slippery road surface, but also the cruising range of the vehicles with the temperature. The reduction has been greatly reduced. For example, a famous electric pure electric car, had more than 80 kilometers of cruising range from the day before, and the next morning, only 30 kilometers were left, and the cruising range was reduced by more than 40 kilometers. Why?

The cruising range decreases at low temperatures, which is related to the structure of the battery.

The most fundamental reason for this phenomenon is that the viscosity of the electrolyte in the battery rises at low temperatures, which causes a series of problems, such as an increase in the internal resistance of the battery, a slow diffusion of lithium ions, etc., which eventually causes the discharge power of the battery to decrease. If you simply compare lithium-ion to a truck in a moving company, the charge on it is the cargo. Under normal temperature, just like a truck driving on a smooth highway, it is fast and efficient. After the temperature drops, it is equivalent to the truck driving in the center of the city at the early peak, and the journey that can be completed in 20 minutes is not sure that it can't be reached for one hour. However, because the number of trucks in the moving company is limited (the number of lithium ions in lithium-ion batteries is limited), the amount of goods shipped per unit time is less.

It is also the metaphor of this moving company. After the morning rush, the roads are unblocked, and the efficiency of trucks transporting goods has returned to normal. If the temperature rises, will the battery life increase again? The answer is yes, but because most of the cars are driving outdoors, they are not easy to detect in daily use, but they are more obvious on mobile phones.

Low-temperature charging is not a solution to the battery.

In theory: in an environment of minus 20 degrees Celsius, it is forbidden to charge the lithium battery (which will cause permanent damage to the battery). And even in a 0-degree environment, the discharge performance of the battery has dropped. In order to solve the problem of using the battery in a low temperature environment, each manufacturer will adopt different power battery low temperature protection measures. For example, some are installed around the battery, and some are heated by the battery to achieve the purpose of heating the battery.

We specially consulted BYD and Tesla's technical experts and learned that in the case of lower temperature, in order to extend the battery life, BYD will lower the upper limit of the charging voltage, and the amount of electricity that is flushed into the battery will be reduced accordingly. And Tesla's suggestion is: the car is plugged in when the vehicle is parked, so that the battery heating function on the car can work better, even if the outdoor temperature reaches minus 20 degrees, the vehicle can be used normally.

Things seem to be simpler. Warm up the battery before charging in the winter. Wouldn't it be better to heat it up? In fact, car companies do the same, the role of the "pre-charge" phase is basically to "warm up" the battery.

Although the principle is simple, it is not so easy to implement. Because most automakers are not like BYD, Wanxiang, and DuPont, and other automakers (polyfluorocarbon announced it holding of Hebei Red Star Motors in August this year, announced its own car-making plan, we will call it a car company for the time being) They started out as batteries, so they all rely on suppliers to provide battery systems. The supplier will specify a safe charging temperature range in the agreement with the car company, and if the car wants to change (such as from 0 degrees to minus 10 degrees), it will cost extra.

Solve the problem of battery in low temperature environment, and rely on technological breakthrough

Because of the material properties of lithium ion batteries, low temperature performance is very difficult to achieve. Lithium titanate batteries, which have satisfactory low temperature performance and charging speed, are not suitable for use on small passenger cars because of their low energy density (already applied to pure electric buses).

[Unveiled] The reason for the reduction of electric car winter battery life: all lithium batteries are funny

After all, compared to fuel cars, electric vehicles have not been widely promoted for a long time, and technology accumulation is not as advanced as fuel vehicles. However, with development of new technologies such as graphene batteries and air lithium-ion batteries, new technologies will soon be able to solve problems of short battery life and low-temperature charging restrictions.

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