New energy electric vehicles give people the impression that the structure is simple and the manufacturing threshold is low, otherwise there will not be so many bigwigs in the industry who say that they can build electric vehicles.
For example, electric cars are considered simple to make because they are a bit like an enlarged version of a remote-controlled car that children play with.
The battery of the remote control car is also a lithium battery, which is the same as that of the electric car; the motor of the remote control car is the motor of the electric vehicle; the receiver of the remote control car is like the electronic control system of the electric car. So, electric cars are indeed not as complicated as traditional fuel vehicles seem.
But if you ask, what is the most important component of an electric car, and what is the answer?
I believe that everyone's answer is basically "battery". Because the battery determines whether the electric car can go, how many kilometers of endurance. The battery problem is also the most discussed topic, which sets off the importance of the battery.
Today's tasting play /tasting driving and everyone to discuss an interesting topic, do you know how the battery of electric vehicles comes from? What are the production steps for electric vehicle batteries? What tests have been tested for batteries installed in your car?
Let's talk about it today.
From the perspective of the composition structure of the power battery of the electric vehicle, it is basically made up of N single battery cells in series and parallel. The battery series between the same unit module, such as multiple 18650 cylinder batteries in series; and the parallel connection between different unit modules, which constitutes a full battery module on the chassis of the electric vehicle.
Figuratively speaking, the bottom of your car is covered with cylindrical batteries, and the electric car is like a huge remote control car. Therefore, the production process of such a single battery is the source of the electric vehicle battery. However, this part of the work is not what car manufacturers are good at, but the responsibility of battery suppliers.
So let's take a look at where the most basic cylindrical batteries come from, that is, what the production process of these batteries is.
Mix the ingredients and stir
The initial process of battery production is to mix and stir the raw materials that can make up lithium batteries, also known as homogenization. The raw materials of the battery include lithium manganate, lithium cobalt oxide, binder, graphite, etc., and stirring them together is the first step.
However, the mixing process seems simple, but the quality of the mixing directly affects the quality of the battery and the pass rate of the finished product. In the process of stirring, it is necessary to strictly control the dust to prevent the dust from affecting the consistency of the battery, so it is the basis in the battery production base.
Plate engineering
We all know that the battery is divided into positive and negative electrodes, after stirring the raw materials, it is necessary to make the positive and negative electrodes of the battery, and with the isolation film, they will form a complete battery.
The purpose of the plate project is to make the cathode plate (copper is the cathode) and the anode plate (aluminum is the anode) inside the battery, and in the manufacturing process of the positive and negative electrodes, it will go through coating, cold pressing, slitting and other processes.
After fully stirring the raw materials, it is necessary to evenly apply these stirred slurries to the copper foil or aluminum foil, which is the process of coating. The coating process must ensure that there are no impurities, otherwise the battery will discharge too quickly and even a safety hazard will occur.
After coating, the pole pieces with the positive and negative electrode materials attached need to be crushed. On the one hand, it is to make the coated material more compact and increase the energy density, and on the other hand, it is also to control dust and humidity.
Then, the cold-pressed pole piece is slitted according to the size of the battery produced according to the needs, which is the source of the battery size distinction. That is to say, whether the 18650 battery or the 21700 battery is distinguished here.
Winding and injection
The positive and negative electrode sheets of the battery are produced well, and in combination with the polar ear and the isolation film, they are combined into a bare battery cell in a winding manner, which basically forms a complete battery shape at this time.
After winding, the "blood" of the battery, that is, the electrolyte, needs to be injected. The electrolyte is the medium that provides energy exchange, that is, the exchange of charged ions. Charged ions are transported through the electrolyte from one pole to another electrode, which completes the process of charging and discharging.
The amount of electrolyte injection is exquisite, if the amount of injection is too large, it will lead to battery heating or even failure; if the amount of injection is too small, it will affect the cycle of the battery, resulting in poor work.
Chemical
The formation of lithium batteries mainly has two functions: one is to convert the active substances in the battery into substances with normal electrochemical effects with the help of the first charge; the other is to make the electrodes mainly negative to form an effective passivation film or SEI film.
Chemical formation first activates the battery cell after the electrolyte is injected. Through charging and discharging, the internal chemical reaction of the battery cell forms a SEI film to ensure the safety, reliability and long cycle life of the battery in the process of charge and discharge cycle.
After activating the battery cell, it also undergoes a series of monitoring such as X-ray monitoring, insulation monitoring, weld monitoring, and capacity testing. In addition, high and low temperature tests and charge and discharge tests are also completed in this link.
Finally, the battery needs to be coded and labeled in order to provide information such as the production batch and date, and if there are any quality problems with the battery, the cause can be found as soon as possible, and the batch can be further screened.
At this point, the small unit battery that makes up the electric vehicle power battery is completed. Grouping and stringing these batteries in parallel has become the foundation of the electric vehicle power battery system - the battery module.
Of course, the battery module is the core component that provides power, but this is not all about electric vehicle power batteries. It is also necessary to have battery management systems, thermal management systems, electrical systems, battery compartments and other components, which are indispensable components to ensure that lithium batteries can work normally and effectively.
These integrated assembly processes, which we usually call PACK.
If the car company completely purchases the finished power battery from the battery supplier, the supplier completes the PACK process. However, this has relatively fixed production requirements for the shape and thickness of the battery module.
In order to achieve the higher energy density of their own developed models and a more reasonable assembly shape, some car companies will also set up their own "PACK workshop", which can be completed by the car companies themselves.
After the power battery is assembled, the battery assembly of the electric vehicle also undergoes some necessary tests, such as static and dynamic detection, high voltage insulation test, water cooling system air tightness test, dustproof and waterproof performance test. Some even need to be assembled on a real car, continue to undergo safety crash tests, and so on.
The safety of lithium batteries is directly related to the safety of the owner's car. Therefore, these tests cannot be ignored, and car companies also attach great importance to it.
In the process of continuous research on the safety of lithium batteries, our independent brand car companies have further improved the thermal management of lithium batteries and protective measures under runaway through their respective patented technologies. Such as The Dayu battery of Great Wall Motors, the blade battery of BYD Automobile, the magazine battery of GAC Aean and so on.
From the mixing and mixing of raw materials to the PACK and testing of power batteries, the seemingly simple battery system has actually experienced too much.
Seeing this, do you also have a preliminary understanding of the birth of electric vehicle batteries? This is the consumer who buys an electric car, and the further understanding of their car. Of course, electric vehicles have many knowledge points that deserve your further understanding, and we will explore them together in the future.