How are lithium batteries built?Three minutes to understand the lithium battery process and manufacturing process

When it comes to batteries, many people will know its basic structure, such as positive and negative electrode ears, positive and negative electrode pieces, diaphragm, electrolyte, etc., but for how the battery is made, very little is known.

And today, I will talk about how the battery is produced, of course, mainly about mobile phone computers and other lithium ion batteries, other equipment battery manufacturing process is much the same, here will not introduce.

First of all, I will talk about the basic manufacturing process of the battery, and then I will introduce each process step by step.

Ingredients coating, rolling and cutting (production) winding / lamination packaging / assembly baking PACK

The above is the basic manufacturing process of lithium-ion batteries. Of course, the large processes may contain a lot of small processes, which will be different because of the battery type, battery model, battery manufacturer, and battery customers.

One, ingredients

The main components of cathode tablet dressing are lithium, adhesive and conductive agent; while the main components of cathode dressing are carbon and adhesive.

This process is to mix the positive and negative materials into a slurry at high speed for the subsequent process to the copper foil.

Pictures are from the Internet

Two, coating

As the name suggests, the application of coating is to apply the positive and negative paste to aluminum foil and copper foil, where the positive aluminum foil and the negative copper foil.

Polar copper foil and its dressing

Three, rolling

Why crush it?

One is because the paste after coating is relatively loose, easy to produce material; the second is the lithium ion battery in order to improve the energy density, the volume of the battery is strictly controlled, and the control of the battery thickness control is naturally the most important.

Now the pole plate thickness control of cell phone batteries is generally controlled between 0.08 and 0.15 mm.

0.13mm

Four, cut

What is the function of the cut?

Mainly is a large volume of positive and negative electrode plate cut into small rolls of positive and negative electrode plate, is designed according to the battery model of the electrode plate width of the positive and negative plate, the negative electrode plate width is wider than the positive electrode plate width.

The purpose is to note that in case the diaphragm at the edge of the negative electrode is damaged and will not short contact with the positive and negative electrode.And if the cell negative electrode is not wider than the positive piece, even if you do not know will appear this case, it must be scrapped.

In addition, generally speaking, the three processes of rolling, cutting and (production) winding / lamination are vacuum fast turnover, that is, the pole film after the rolling day is sent to (production) rolling / lamination production line for production, and the midway is to be packaged to avoid the contact with the air for a long time.

However, some factories do not have this condition, so after the cutting, the pole sheet will be baked, only to the winding / laminated production line for production.

Why do you bake it?

Because the pole plate, especially the negative electrode plate after long-term contact with the air will absorb the water in the air, resulting in the pole plate thickness.

Baking is to remove water, in the later process there will be a baking process, but also to remove water.

Small roll negative used for winding

V. (Production) A winding / laminated film

Why production brackets?

Because in some process design, the production has been integrated with the winding into a process, and some are a separate process.

Here we want to talk about the design process of the battery pole ear, the battery pole ear has a unipolar ear and multipolar ear difference.

Monpolar ear refers to the positive and negative poles, while the multipolar ear has more than one positive and negative pole.

Generally, combined batteries are mostly used with multi-polar ears, and high current requirements for single batteries are also used with multipolar ears.

The production process of the multi-pole ear battery is separate, first welding the pole ear to the positive and negative electrode film, and then transfer to the subsequent process.

The subsequent process is winding and lamination, winding and lamination are only two different processes, the positive electrode plate, negative electrode plate, diaphragm winding and folded into the cell process.

If it is a monopolar battery, the production and winding can be done on the production winding in one automatic device, and the polar ear is also automatically welded on the winding machine.

As for the lamination process, whether it is uniolar or multipolar battery, the production process is separate, either in a separate production line or in the cutting workshop.It is the first slice according to the size of the slice, before the lamination machine folded into the core.

up-coiler

Vi. Packaging / assembly

Packaging and assembly are two different battery processes, packaging for soft packaging battery, assembly for hard shell battery, soft packaging is aluminum plastic film, hard shell battery is aluminum shell.

Soft packaging batteries will have film on the pole ear for packaging, while aluminum shell batteries are not.

Now smart phones are generally not removable battery design scheme, so soft packaging batteries will be more.

Packaging is to put the pole core into the aluminum plastic shell, and then use high temperature pressure on the side and top of the aluminum plastic film, so that the film on the polar ear of the positive and negative electrode and the material in the aluminum plastic film melt and then solidify, there is the role of sealing, only one air bag mouth for injection of electrolyte.

The assembly is the battery into the aluminum shell, with the positive and negative ear welded to the aluminum cover plate, and then use the laser welding welding cover plate and aluminum shell, cover plate on the injection hole for injection.

Soft packaging cell

Seven, baking

Baking can also be classified as a liquid injection process, and the effect of baking is to remove moisture.Because the water residue in the cell is easy to produce chemical reactions, resulting in the battery bulge.

Vacuum baking box

Eight, injection

After baking, the electrolyte can be injected.Electrolyte is only one of the electrolytes, but also has the semi-solid electrolyte and the solid electrolyte, which belongs to the polymer lithium battery, relatively few.

In the injection process, soft packaging battery and hard shell battery are different.

The hard shell battery will first inject a little electrolyte, and then the first short time of charging, charging after the second injection, and then seal the injection hole with steel beads.

Soft packaging battery is different, soft packaging battery once complete the injection, and then seal the side of the airbag bag with high temperature.This closure will be a little wider than the cell body, because there is a subsequent closure.

Nine, chemical composition capacity

Transformation is to charge and discharge the battery to form a passivation layer that covers the surface of the cathode material.The passivation film is called a solid electrolyte interface film (solid electrolyte interface), or an SEI film, acting as a conductor of lithium ions.

After the conversion, the soft packaging battery will have one more process than the hard shell battery.Because the soft packaging battery uses aluminum-plastic film, it will produce gas in the formation process, so it is necessary to puncture the airbag bag, and then pull the gas out, and then conduct the second sealing.The excess side and airbag bags will be cut off after the second closure.

After the formation is the capacity, the capacity is just the capacity to pick out the bad capacity.

Component capacity equipment

Ten, detection

After the capacity, the qualified products will be transferred to the testing process, will test the appearance and weight of the battery, and then voltage detection, internal resistance detection, high pressure detection, voltage detection, uniformity detection and so on.

eleven, PACK

First, in the battery manufacturing process, the monomer after laminating or winding process is called polar core; the monomer packaged or assembled until before the PACK is called electric cell, and the monomer after the PACK process is called battery.

But by the step before PACK, the cell completion degree is already very high, so some battery factories will outsource PACK to third-party manufacturers.

For single batteries, PACK just adds protective boards, connecting pieces and other items to the cells; for combined batteries, the cells are also combined together, but in the mobile phone industry few combined batteries, and there are many shanzhai charging banks.

Of course, there are a combination of batteries are combined in the assembly process, but that is not used for mobile phone products, this article will not say.

After the PACK process is completed, a normal usable battery is born.