Battery Production Process

How lithium polymer batteries are made

A photo walkthrough of the full production flow — from raw electrode slurry to a tested, sealed, and packed battery.

01Inside the Factory 02Electrode Preparation 03Electrode Creation 04Forming & Electrolyte Filling 05Formation Charging 06Battery Pack Creation 07Cylindrical Cell Covering 08Safety & QC Testing 09Large Battery Packs

Inside the Factory

A multi-building battery manufacturing campus, where each position along the assembly line has its own uniform, safety gear, and documented workflow.

Battery manufacturing campus with dedicated production buildings.

The step-by-step flow every LiPo cell follows.

Position-specific uniforms and safety gear on the line.

Electrode Preparation

Active material is mixed into a slurry, coated onto metal foil, cured in a long oven, pressed thin, and cut to width.

Mixing the coating material for anode and cathode.

Large rolls of raw foil loaded into the coating machine.

A thin layer of carbon-lithium slurry applied in swaths onto the foil.

A ~20 m oven cures the slurry onto the terminal material.

Two continuous coating lines: anode and cathode.

Calendaring press squeezes the sheets thinner, like a pasta machine.

Cutting the large sheets to the proper width.

Electrode Creation

Rolls become electrodes: terminals are welded on, sheets are cut to length, and anode, separator, and cathode are folded together.

Machines attach tabs and cut electrodes to length.

Rows of electrode machines running in parallel.

Anode, semi-permeable membrane, and cathode folded together many times.

Semi-automatic wrapping: the operator aligns electrodes, the machine does the rest.

Forming & Electrolyte Filling

The pouch housing is formed, electrodes are sealed inside on three sides, electrolyte is pumped in under tight humidity control, and the fourth side is welded shut.

Pouch housings formed in a separate room.

Machines cut and form the slightly flexible protective housing.

Electrodes inserted and thermally welded on three sides.

Electrode stacks in their housing, one side left open.

Electrolyte pumped into the cell in a humidity- and temperature-controlled room.

The fourth side is thermally welded to seal the battery.

Formation Charging

Sealed cells get their first charge, then are heavily compressed and baked to force out air, and excess electrolyte is trimmed away.

First charging cycle — clips clamp onto the exposed tabs.

Racks of chargers running the formation cycle.

An entire floor dedicated to charging cells.

After first charge, cells are strongly compressed.

Heavy compression forces out any remaining air.

Cells bake under compression for several hours.

Excess electrolyte in the side pillow is removed.

A finished single cell — protection circuit still to come.

At scale: tens of thousands of cells per day.

Battery Pack Creation

The protection circuit (PCM) guards against overcharge, over-discharge, and short circuit. Wires, tape, and structure turn a cell into a battery.

The protection circuit prevents overcharge past 4.3 V, discharge below ~2.8 V, and short circuit.

A formal battery: PCM under kapton tape, with positive and negative leads.

A two-part battery design for split device layouts.

Each battery model runs on its own dedicated line.

Cylindrical Cell Covering

On a separate line, LiFePO4 cylindrical cells get their heat-shrink labels and pass through a heat tunnel.

LiFePO4 cells being made — the process is nearly the same as LiPo.

Heat-shrink labels applied automatically, then through the heat tunnel.

Safety & QC Testing

Every production batch sends samples to the torture lab: oven, crush, puncture, stake, and fold tests verify the cells fail safely.

The materials engineer leading the QC walkthrough.

A caged room with eight failure-testing machines.

The oven that pushes batteries to their limit.

The battery crush tester squeezes cells laterally until failure.

Puncture test: a 10 kg mass drops 1 m onto a 10 mm rod.

The stake test — poking until ignition behavior is known.

The fold test bends cells over triangular steel at extreme angles.

After testing, cells are unrolled and the failure vector evaluated.

Large Battery Packs

In a separate room, very large packs — up to 100 Ah, nearly 5000 Wh — are built and tested for applications like electric buses.

Large-format packs built and tested in a dedicated room.

3.7V at variable capacity and voltage, with certification to our customer

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