Lithium Battery Separator Thickness Measurement

New Energy02.Lithium Battery Separator Thickness Measurement with Chromatic Confocal Sensors

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New Energy02.Lithium Battery Separator Thickness Measurement with Chromatic Confocal Sensors

Aug 19, 2025

1. Importance of Separator Thickness Measurement

In lithium-ion battery manufacturing, the separator plays a critical safety and performance role:

Uniform ion transport – thickness consistency ensures balanced lithium-ion movement.
Battery safety – overly thin separators risk short circuits, while overly thick ones reduce energy density.
Production yield – precise measurement minimizes defects and improves reliability.

Accurate separator thickness measurement is therefore essential for stable, safe, and high-capacity batteries.

2. Common Measurement Methods

Method	Principle	Advantages	Limitations
Contact micrometer	Direct probe measures thickness	Simple, low cost	Contact may deform soft separator material
Beta-ray / X-ray gauge	Radiation absorption through material	High accuracy, inline applicable	Requires radiation safety, limited material contrast
Laser triangulation	Reflection angle detects distance	Non-contact, fast	May struggle with transparent/semi-transparent films
Chromatic confocal sensor	Wavelength dispersion focuses at different depths	High resolution, non-contact, works on transparent films	Cost higher than contact methods

3. Principle and Process of Chromatic Confocal Measurement

The chromatic confocal displacement sensor projects white light through a lens system, which separates wavelengths by focal position:

Dispersion – different wavelengths focus at different depths.
Reflection detection – only the wavelength in focus reflects sharply from the target surface.
Spectral analysis – the sensor detects this wavelength and calculates the exact distance.
Thickness calculation – by measuring both top and bottom surfaces of the separator, the system obtains thickness.

This principle makes it ideal for transparent and multilayer materials such as lithium battery separators.

4. TronSight’s Solution

The TronSight TS-C Series Chromatic Confocal Displacement Sensor is designed for precision thin-film and transparent material measurement:

Up to 32kHz sampling rate, suitable for inline inspection.
16-channel fully synchronized measurement, supporting multi-point evaluation.
Probe angle up to ±60°, adaptable to varied installation conditions.
Minimum probe diameter φ3.8mm, suitable for compact environments.
High-temperature and vacuum compatible, meeting advanced manufacturing requirements.
Supports multi-layer transparent measurement, perfectly fitting lithium battery separator inspection.

Application Example (conservative wording):
In lithium battery separator production, TS-C sensors measure top and bottom surfaces to determine separator thickness. The collected data can be used by inspection systems to verify uniformity and support production quality control.