How PID Sensors Mitigate Leak Risks in Lithium-Ion Production?

As lithium-ion battery manufacturing scales at an unprecedented pace, precision environmental monitoring has become critical to safety and compliance.

Global lithium-ion battery production is experiencing significant technological advancements. Capacity is expected to exceed 3 terawatt-hours (TWh) by 2024, with industry leaders such as CATL producing 670 gigawatt-hours (GWh) and BYD producing 157 GWh. As European and North American battery manufacturing accelerates, leaders like LG Energy Solution (520 GWh global capacity by 2025, 41% in North America, SPGlobal) and SK On (200+ GWh target, Reuters) are scaling next-generation facilities. Panasonic’s new 30 GWh 4680 cell plant in the US and Northvolt’s 150 GWh German gigafactory (2030 target, Beadszirconia) further signal a regional shift toward localized, tech-driven production.

Manufacturers face intensifying demands for environmental control precision. Three key drivers are reshaping quality protocols:

1. Stricter Emission Standards

To improve air quality, global regulations aim to reduce volatile organic compound (VOC) emissions to near-zero in various industries. This requires real-time monitoring that goes beyond traditional methods.

2. Next-Generation Battery Production

Emerging solid-state battery processes demand ultra-dry, oxygen-free environments throughout more manufacturing stages. Similarly, automated "dark factory" concepts necessitate closed-loop environmental control with zero tolerance for contaminants.

3. IoT-Integrated Manufacturing

Smart factories increasingly require continuous feedback systems that dynamically adjust air handling during critical operations like coating start/stop cycles or personnel movement.

This is where PID sensors become critical for early electrolyte leak detection – identifying ppm-level vapor emissions during formation, aging, or storage preventing thermal risks from arising.

PID sensors now emerge as a core safeguard — enabling:

▶ Early identification of ppm-level solvent vapor leaks

▶ Dynamic feedback integration with factory IoT systems

▶ Compliance with tightening global emission thresholds

From a technological standpoint, power lithium-ion batteries can be classified as follows:

By cathode material: ternary lithium batteries and lithium iron phosphate (LFP) batteries；

By packaging format: pouch cells, prismatic cells, and cylindrical cells；

By electrolyte type: liquid-electrolyte batteries and solid-state batteries

Why do lithium-ion battery leaks generate VOC emissions?

The release of VOCs from lithium-ion batteries primarily originates from multiple stages of their manufacturing process, including active material preparation, electrolyte production, coating, electrolyte filling, cell assembly, formation (electrochemical conditioning), and testing. The specific sources of VOC emissions and their typical constituents are as follows:

Active material preparation:

In this stage, off-gases consist mainly of particulate dust, metal oxides, and evaporated organic solvents (VOCs) such as N-methyl-2-pyrrolidone (NMP).

Electrolyte production:

Preparation of the electrolyte generates VOCs containing lithium hexafluorophosphate (LiPF₆) and carbonate-based solvents, which are both volatile and may present strong odors, flammability, and explosion hazards.

Coating and filling:

During electrode coating, solvents within the slurry volatilize and form VOCs; during electrolyte filling, leakage or evaporation of the liquid electrolyte can release further VOCs into the atmosphere.

Cell assembly and formation: Poor sealing of the cell enclosure can lead to leakage of internal gases; during formation (the initial charge/discharge cycles), electrochemical reactions inside the cell generate gases such as hydrogen and oxygen, as well as small amounts of organic vapors.

Testing:

In performance testing (cycling, capacity checks, etc.), charging and discharging can cause additional VOC emissions, which may include a mix of organic compounds, inorganic gases, and particulates.

How to detect a lithium-ion battery is leaking? --- PID-Based VOC Leak Detection Technology for Lithium Batteries

Photoionization detector (PID) sensors have become a transformative solution for detecting VOC leaks in lithium-ion battery manufacturing. At the core of a PID sensor is a high-energy ultraviolet (UV) light source. When VOCs enter the sensor’s ionization chamber, the high-energy photons emitted by the UV source interact with organic molecules. For a detailed explanation of this principle, see the article What is a PID Sensor. With ultra-high detection precision—sensitivity up to 1 ppb—a PID can accurately capture micro-leaks down to 0.01 mm in size, boosting leak-detection accuracy to over 99.9% and effectively solving the challenge of detecting extremely small leaks.

Efficient production-line integration:

With an integrated equipment design and automated inspection workflow, it perfectly aligns with customers’ high-volume manufacturing needs. Single-cell testing takes just 5 seconds, and when paired with a rapid loading/unloading system, overall production efficiency is greatly increased while labor costs are reduced.

Non-destructive inspection assurance:

As a non-destructive testing device, it inflicts no damage on the battery during inspection, ensuring that battery performance and service life remain unaffected—while also avoiding additional cost losses from improper handling.

Stable, reliable performance:

The system’s GRR (Gauge Repeatability and Reproducibility) is under 10%, providing outstanding stability and consistency. It runs continuously and fault-free over the long term, delivering dependable quality-inspection assurance for customers.

How to Use PID Detection

On the battery production line, install a dedicated inspection station and rapidly place the cell under test into the device’s fixture. With a single-button start, the equipment automatically seals around the battery and employs photoionization detection (PID) technology: a UV lamp irradiates the battery’s internal volume, ionizing any volatile organic compounds (VOCs) released by leaked electrolyte into charged particles. These particles generate a faint current signal, which is then amplified and processed linearly to yield a VOC concentration reading. This allows for an accurate, immediate determination of whether the cell is leaking— the entire process takes only a few seconds.

Summary

PID-based detection is currently the optimal solution for identifying VOC leaks in next-generation lithium-ion batteries. PID detectors can be built as compact, portable units that flexibly fit anywhere on the production line for more precise monitoring of VOC emissions during battery manufacturing. Compared with FID technology, PID offers faster response times and smaller form factors. Deploying a PID detection system for lithium-battery VOC leaks can reduce customer product leak-rate defects from 3% down to below 0.1%, effectively lowering after-sales recalls and repair costs while boosting market competitiveness. As solid-state battery mass production approaches, new polymer solvents (e.g., PEGDME) will drive a fresh wave of PID-technology upgrades.

For VOC-concentration monitoring in next-generation lithium-battery leak detection, the ION Science OEM gas-sensor portfolio delivers market-leading photoionization technology capable of detecting VOCs at extremely low levels (down to 1 ppb). Measurement ranges from 0 to 4,000 ppm are available, and sensors can be used standalone or seamlessly integrated into end products.