Quality Control Services for Li-ion Battery Products in Asia

Process 1. Electrode Coating

Key Processes:

Active materials (such as LiCoO₂ or LiFePO₄ for the cathode, graphite or Si-C for the anode) are mixed with conductive agents and binders to form a slurry, which is uniformly coated onto current collectors (aluminium or copper foil).

Main Equipment:

Coating Machine, Mixer, Drying Oven.

Common Issues:

Uneven slurry, uneven coating thickness, uneven coating area density, powder shedding/cracking, edge defects, and metallic impurities.

Process 2. Electrode Calendering

Key Processes:

Dried electrodes are calendered to achieve the desired thickness and density, improving energy density and uniformity.

Main Equipment:

Calendering Machine, Thickness Gauge.

Common Issues:

Uneven calendering thickness, substandard electrode density, surface indentations/scratches, electrode deformation/wrinkles, active material shedding.

Process 3. Slitting

Key Processes:

The calendered electrode rolls are slit into specific widths for subsequent winding or stacking.

Main Equipment:

Slitting Machine, Electrostatic Dust Removal System.

Common Issues:

Out-of-tolerance slitting width, edge burrs/powder shedding, slitting breakage, electrostatic adsorption, and uneven winding.

Process 4. Cell Assembly (Winding / Stacking)

Key Processes:

Cathode, separator, and anode are wound or stacked in sequence to form the cell core.

Main Equipment:

Winding Machine, Stacking Machine, Separator Unwinder.

Common Issues:

Alignment deviation, separator wrinkles/damage, electrode damage, foreign object contamination, over-tight/loose winding/stacking.

Process 5. Cell Enclosure & Welding

Key Processes:

The cell core is inserted into the housing, and tabs, leads, and safety vents are welded securely.

Main Equipment:

Laser Welding Machine, Spot Welder, Casing Machine.

Common Issues:

Cold solder joints/false welding, welding perforation/burn, poor sealing, tab breakage/damage, improper safety vent installation.

Process 6. Electrolyte Filling

Key Processes:

Electrolyte is injected into the cell under vacuum to ensure full wetting of the electrodes and the separator.

Main Equipment:

Vacuum Electrolyte Filling Machine, Vacuum Oven.

Common Issues:

Inaccurate electrolyte volume, electrolyte leakage, electrolyte contamination, incomplete wetting, and gas bubble residue.

Process 7. Formation & Aging

Key Processes:

Charge-discharge cycles form a stable SEI layer and stabilize electrochemical performance, while defective cells are eliminated.

Main Equipment:

Formation Cabinet, Aging Rack, Charge/Discharge Tester.

Common Issues:

Poor SEI layer formation, rapid capacity degradation, excessive self-discharge, abnormal voltage, abnormal temperature rise, low formation efficiency.

Process 8. Capacity Grading & Sorting

Key Processes:

Measure cell capacity, internal resistance, and voltage consistency, then sort by performance grade.

Main Equipment:

Grading Cabinet, Internal Resistance Tester, Sorting Machine.

Common Issues:

Insufficient sorting accuracy, inaccurate internal resistance test, inaccurate capacity test, misjudgment/missed judgment, and low sorting efficiency.

Process 9. Packaging & Final Inspection

Key Processes:

Qualified cells are packaged, labeled, wrapped with protective materials, and undergo final visual and safety inspection.

Main Equipment:

Packaging Machine, Labeling Machine, Withstand Voltage Tester.

Common Issues:

Appearance defects, incorrect/missing labels, packaging damage, missing accessories, substandard safety performance test, incomplete cleaning.