What Are The Secrets About Lithium Batteries?

There are two types of electric vehicle batteries known at present, which are divided into ternary lithium batteries and lithium iron phosphate batteries according to the difference of the positive electrode material. It is just that the activity of the lithium iron phosphate battery is poor, resulting in a low energy density and unable to provide longer battery life, so it gradually fades out of sight.

The current mainstream ternary lithium battery has the advantages of high battery activity and higher energy density, so new energy models basically use ternary lithium batteries as energy storage mechanisms.

No matter what kind of lithium battery, its basic structure is the same. They are composed of positive electrode, negative electrode, separator and electrolyte. The charging of a lithium battery is to generate charged lithium ions (equivalent) from the positive electrode and detach from the positive electrode, "swim" the electrolyte and the separator to reach the negative electrode, and embed it in the negative electrode material. The discharge process is just the opposite, with lithium ions "swiping" from the negative electrode to the positive electrode. In simple terms, the charging and discharging process of a lithium battery is achieved by lithium ions "swimming" between the positive and negative electrodes.

It is the electric current that pushes lithium ions to "swim" back and forth. So we can simply understand fast charging as a high-power propeller behind lithium ion, which quickly and forcibly pushes lithium ions to “swim” from the positive electrode to the negative electrode, while slow charging is a low-power propeller, with lithium ion slowly "Swim" from the positive to the negative.

So why does fast charging affect the battery? Quite simply, many lithium ions with high-power thrusters “crazyly swim” from the positive electrode to the negative electrode. Before the negative electrode has landed (embedded in the negative electrode), another lithium ion rushed over and two lithium ions hit Together "killed to death" inactivated. As a result, the battery loses one lithium ion. Over time, "dead" lithium ions will accumulate and form lithium dendrites. Many battery deflagrations occur, and most of them are caused by lithium dendrites piercing the separator and causing short-circuits inside the battery.

In addition, let's extend it again. Why does the battery life of electric vehicles shrink dramatically in the low temperature in winter? As mentioned earlier, the discharge process of the battery is that lithium ions are de-intercalated from the negative electrode, and then "liquid back" to the positive electrode through electrolysis. At low temperatures, the electrolyte can become "sticky" or even "freezing." This means that the process of lithium ions "swimming back" from the negative electrode becomes more difficult, and more powerful thrusters are needed to push the lithium ions, which means that the internal resistance of the battery increases.

Therefore, the battery itself needs to consume more power at low temperatures, which leads to a reduction in the power required to drive the vehicle. This is why the battery life of electric vehicles has shrunk sharply in winter.