VITRONIC has developed a process for the quality inspection of lithium-ion batteries for electric vehicles, to detect particle contamination in battery cells. In rare cases, particles can cause short circuits, as a result of which the battery can ignite during operation. As the production volume of Li-ion batteries will multiply in the coming years, this could result in a relevant safety problem. The new process offers a solution: it enables inexpensive, continuous inline inspection in mass production.

Particle contamination as a cause of battery fires

When electric vehicles catch fire as out of nothing, they could be responsible: production residues just micrometers in size in the cells of lithium-ion batteries. They stem from the electrodes and separator foils being cut to size or from the abrasion of mechanical parts in the production line. Despite cleaning systems, individual particles remain stuck on the foils of the battery cell. 

When particles are 10 micrometers and larger, they can penetrate the 10-40 micrometer thick separators between the anode and cathode. This usually happens only after the batteries have been in use for a while - perhaps during a car trip. The battery shorts, can ignite and set the entire vehicle on fire. 

The problem has been accepted so far

With the usual quality controls in battery production, such particle contamination cannot be detected; at the time of delivery, the battery is still functioning normally. Available inspection systems - industrial microscopes - must be operated manually. They are only suitable for spot checks, but not for mass production. 

Due to the relatively small number of units produced to date, the safety risk could be accepted up to now. However, the current figure of around 20 million e-vehicles worldwide is expected to grow into hundreds of millions in the coming years. The current individual cases could then become a relevant number of incidents. 

Inspection system for mass production is currently being tested

Seamless particle inspection will therefore soon become standard in battery production. The new process from VITRONIC, the specialists for industrial image processing, offers a solution for this. A high-resolution 16k camera sensor simultaneously takes several images of the electrode foils from different angles, with different illumination. This makes it possible to detect tiny particles that have hardly any contrast with the background and are practically invisible. The detected particles are measured and automatically classified. Other flaws can also be detected, such as position deviations, edge and cutting defects, or surface defects of the electrodes caused by transport. 

The inspection is performed directly in the production line, after laser cutting and before stacking the electrode and separator foils. The transport of the foils does not have to be interrupted for this. The inline inspection system is therefore suitable for use in mass production. It supports battery cell manufacturers in further increasing product quality and implementing a zero-defect strategy. 

At the Battery Show in Stuttgart from June 28-30, 2022, VITRONIC will present these and other innovations in quality inspection. Interested parties can find more information here.

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VITRONIC is a world leader in industrial machine vision. The owner-managed group of companies develops innovative products and customized solutions in the growth industries of automation, healthcare, photovoltaics, logistics automation, body scanning solutions, and traffic technology.

With over 35 years of experience, VITRONIC offers a unique portfolio of systems and software for image and sensor-based quality inspection, identification, traffic monitoring, and toll collection. Customers include renowned companies such as B.Braun, BMW, Daimler, DHL, UPS, Toll Collect, Fresenius, and Sanofi, as well as government agencies and public authorities.

VITRONIC systems play a major role in ensuring the highest levels of quality and efficiency in the production processes of the automobile, photovoltaic, and pharmaceutical industries.

In logistics centers and cargo airports worldwide, VITRONIC's Auto-ID solutions efficiently capture and integrate shipment data and ensure the transparent flow of packages.

In the traffic technology sector, VITRONIC offers high-performance technologies to increase road safety, improve traffic flow and secure tolling revenue.

Since its founding in 1984, VITRONIC has grown continuously, and currently has over 1,000 employees.  It is represented in four continents and in over 80 countries. VITRONIC supports its international customers through its subsidiaries in North America, Europe, Asia and Australia, as well as through a global network of sales and service partners.

VITRONIC systems are developed and manufactured at the company's headquarters in Wiesbaden, Germany. In 2020, the Group’s total revenue was 152,5 million Euros.

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