Why the power battery of new energy vehicle decay?

At present, the industry regulation is that the battery should be changed when its attenuation is up to 80. There are two mainstreams of power battery so far. Let's look at it separately:

One is the ternary lithium battery represented by tesla, which has higher energy density, small size and light weight. However, as heat dissipation is a big problem, it needs extra space and quality to install water-cooling cooling system, and its safety is not as good as that of iron battery.

In addition, its battery attenuation is relatively fast, about 800-1200 full charge cycle, on the attenuation of 20%.

Full charge means that only 0-100% charge is counted once, and if the charge goes from 50-100%, half charge is counted.

According to the mileage of 300 km, the replacement standard is between 240,000 km and 360,000 km, and according to the mileage driven by the family car every year, it will take more than ten years anyway.

The other is the lithium iron phosphate battery (iron battery), which is represented by byd. This kind of battery has the opposite performance as the ternary lithium battery, and its small density correspondingly results in large volume, high quality, good heat dissipation characteristics, and its safety is also better than the ternary lithium battery.

Its battery has a slower thermal decay, about 20 percent after 2,000 cycles, but because of its short range, its life is about the same as a lithium battery.

As for why the battery will appear attenuation, I will give a brief introduction.

I have read several research reports from American scholars. To put it simply, in a lithium battery, there is a layer of exchange membrane through which lithium ions pass back and forth to complete charging and discharging.

After multiple charges, a small fraction of the lithium ions become inactive and become "deposited lithium ions." they form an "electrical insulating shell" inside the battery, and the thicker the shell, the worse the battery's performance.

In addition, during discharge, some lithium ions will be consumed to supplement the damage of the exchange membrane. At this time, due to the reduction of lithium ions, the driving range will be reduced.

At present, this problem cannot be completely solved from the perspective of hardware. We can only start from the electronic control system and use various algorithms to figure out how to increase the range and reduce the attenuation. As far as I know, tesla is the best in the world in this aspect.

Of course, obviously, China's ZF is aware of the characteristics of lithium battery, so the provisions of electric car battery warranty as long as 8 years / 150,000 km, within this as long as the replacement standard, then 4S shop to be free of charge replacement, this point the country is very thoughtful.

Of course, it is not enough to protect the rights and interests of consumers by law. We should pay more attention to it in ordinary use and reduce the battery loss at the source. After I asked relevant engineers, I have two points to pay attention to:

1. Try not to step on the accelerator pedal (switch) every day, because when you step on the switch, the electronic control system will send a signal, let a large number of lithium ions in a short time to converge in the discharge end, in the long run this will reduce the activity of some lithium ions, and accelerate the loss of exchange membrane, thus increasing the loss of the battery.

2. Do not always use quick charging technology, because during quick charging, lithium ions quickly gather at the charging end and pass through the exchange membrane to complete the task, thus accelerating the generation of electrical insulation shell in the long run.

Actually, to put it bluntly, electric attenuation is not fearful because the replacement fee will be lower as along with the development of battery technology. Besides, it is not common that people would drive a car for more than ten years. Instead, most of the people would choose to get a new car after the usage of 6 or 7 years. Therefore, a  used car is OK, for its consumption only of 20%. A car of 10 years still has 20% after the power loss!

The page contains the contents of the machine translation.