Preparation and process flow of 18650 lithium battery

Preparation and process flow of 18650 lithium battery

Preparation of pole pieces

(1) Ingredients

Positive electrode: put a proportion of polyvinylidene fluoride (PVDF) and nitrogen methylpyrrolidone (NMP) into the stir

Mix in the mixer and adjust the stirrer speed; then add the positive active material and carbon black, vacuum, adjust.

The speed of the agitator.

Negative electrode: Mix the latex and water in a blender and mix to adjust the stirrer speed; then

Add CMS, vacuum and adjust the stirrer speed.

(2) Coating.

The aluminum strip (the negative electrode is a copper strip) is placed flat on the coater, and the aluminum strip is not biased, wrinkle-free.

Smooth belt, no leakage, no slip. Spread the prepared slurry evenly on the machine and set the corresponding parameters.

These include the positive draw speed, the negative draw speed, the oven temperature, and the coating width. In the process of carrying.

Observe whether the slurry is straight, no inclination, no misalignment, and whether the thickness of the slurry coated on the aluminum strip (copper strip) is uniform,

Consistent.

(3) Vacuum drying.

The coated positive and negative electrodes were placed in a vacuum oven for drying, and the degree of vacuum was -0.09 MPa.

(4) Cut large pieces.

Cutting the coated positive electrode sheet into a certain length (depending on the specific battery design), the film cutting machine

The walking speed is 55mm/min, and the incision is required to be free of burrs.

(6) Scraper

The slurry at one end of the positive and negative electrode sheets was scraped off to prepare for ultrasonic spot welding, and the double-sided blade was used.

(7) Rolling

The strip piece is pressed into a certain thickness of the pole piece for winding, and the thickness of the pole piece is strictly controlled during the pressing, and the pressure is pressed

The deviation between the end and the end of the pole piece shall not exceed 0.010mm. At the same time keep the tablet machine clean and clean with alcohol every 2 hours.

One tablet press.

(8) cut small pieces

Cut the cut large piece into strips of a certain width (depending on the specific battery design), and ask to cut

No burr.

(1) Welding ear.

The positive electrode (aluminum strip) and the negative electrode (nickel strip) are respectively welded to the positive and negative electrodes by an ultrasonic welding machine.

The position of the blade. Pay attention to prevent welding deviation, welding misalignment, and virtual welding.

(2) Winding

Place the ion exchange membrane flush on the winding needle, and the front end protrudes 2-5mm from the needle, and the four corners of the pole piece are not

Can wrinkle, the pole piece cannot be dropped, the tape is inclined, the single-sided tape is too long, the double-sided tape is dislocated, the tape

Without covering the defects such as solder joints, the positive electrode material must hold the negative electrode material, the pole piece cannot be rolled, and the front end of the pole piece must

Must be inserted into the top.

Check the winding defects: the ion exchange membrane is not aligned, that is, the positive and negative electrodes are beyond the exchange membrane; the high sheet is low; the pole piece is not

Put it in place, the positive end of the outer ring does not hold the negative end, and the positive and negative inner sheets of the inner ring have the top of the exchange membrane.

Coincidence, there is still a distance; the exchange film holds the negative electrode tail too tight; the positive electrode aluminum strip and the negative nickel strip are too long and short;

Poor adhesive at the end of the core; the battery core is not rolled in place: the positive and negative ear spacing is wide or narrow; the exchange film is not flattened

Wrinkling; positive curling; positive sheet not curled, notched; exchange film not completely entangled negative tail; inner and outer pole

The piece is misplaced.

(3) Bottom welding

First put the insulating gasket into the steel shell, then put the wound electric core into the steel shell, and use the spot welder to turn the negative electrode

Soldered at the bottom of the steel shell. Check the outer surface of the bottom of the steel shell, and pick out the appearance of yellow, black, defects, and fire.

And try to pull the ear, pick the fire, solder, disordering and other spot welding is not strong battery.

(4) Sealing

First use a spot welder to weld the steel shell and cap of the battery, and then use laser welding machine for continuous laser welding.

Pick up. Laser welding should ensure accurate positioning, cleaned parts, no deformation or damage to the battery, post-weld inspection

Check and repair the defective batteries with solder holes and fire.

(5) Baking

Baking for 12 hours under the condition of constant temperature and vacuum of -0.09MPa, the main purpose is to dry the battery

Moisture.

(6) Injection.

The vacuum-baked battery fill into electrolyte in a glove box filled with Ar gas, and amount of liquid inject according to battery different design. Battery should be weighed before and after injection, and weight difference so we could know if liquid injected amount is enough or not.

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