# Li\-ion Cell Factory Manufacturing

By J

Topic: Engineering

[Open the interactive Jig](https://ask.jig.com/j/Up4h5w2jjPZO)

## Guide

### 1. A battery factory in miniature

Phone and electric\-car batteries are built from smaller units called cells\. Here a whole cell factory is shrunk onto one table\. Follow the line from left to right to see black powder become a working lithium\-ion cell\.

The line follows the EU GIGAGREEN project's 2026 guidelines for the cell factory of the future\. Drag to turn the view\.

### 2. Mixing the slurry

First, fine powders are stirred into a liquid to make a thick black paste called slurry\. It looks like paint, and it holds the materials that will store energy\. The factory of the future mixes with water instead of a toxic solvent called NMP\.

Two slurries are made, one for each side of the battery: the negative side \(here graphite and silicon\) and the positive side \(a lithium metal oxide\)\.

### 3. Painting the foil

A slot die, a nozzle as wide as the foil, spreads the slurry in one smooth, even layer\. Underneath runs metal foil thinner than a hair: aluminium for the positive side, copper for the negative\. Coated foil is called an electrode\.

Battery foils are about 6 to 20 micrometres thick\. A human hair is about 70\.

### 4. Drying in the oven

The wet electrode glides through a long, warm oven until the liquid is gone\. Dry it too fast and the coating can crack, so this slow step often sets the pace\. A factory runs only as fast as its slowest steady step\.

Water\-based slurry needs less energy to dry than the solvent it replaces, one way the future factory cuts waste\.

### 5. Pressing it flat

Two heavy steel rollers squeeze the dry coating, a step called calendering\. Like rolling out dough, it makes the layer thinner and denser, so more energy fits into less space\. The finished electrode is wound onto a big roll\.

Pressing shrinks the tiny air gaps in the coating from over half of it to about a third\.

### 6. Stacking in the dry room

In a dry room, with air drier than a desert, the rolls are cut into sheets\. A robot stacks them like a sandwich: negative electrode, separator, positive electrode, separator, again and again\. The separator is a thin plastic film that keeps the electrodes from touching\.

One electric\-car cell held 19 negative sheets, 18 positive sheets and 38 separators\.

### 7. Filling and sealing

The stack is closed in a soft foil bag called a pouch\. A needle adds a little liquid, the electrolyte, which lets tiny charged particles called ions travel between the layers\. Then the last edge is heat\-sealed shut\.

A cell is not a tank of liquid: the electrolyte simply soaks into the thin layers\.

### 8. The very first charge

Now every cell is charged for the first time, slowly, in big racks\. This step, called formation, grows a very thin protective skin inside the cell\. Then the cells rest for days, called ageing, so any weak ones show themselves\.

Formation and ageing take days and fill whole halls with racks, so they are a costly part of the factory\.

### 9. Tested and ready

Each finished cell is measured before it leaves the factory\. Hundreds of cells together can drive an electric car\. Designing every step to run smoothly, with less waste and cleaner materials, is the goal of the factory of the future\.

Look for the small maker's mark on the test stand\.