Directly detect micro-leaks in filled and sealed battery cells: precise, non-destructive, and automatable.
MACEAS develops customized test systems for direct electrolyte leak testing of battery cells. The test method, vacuum chamber, cell holder, part handling, and evaluation are adapted to the cell format, electrolyte, limit leak rate, and cycle time.
Unlike indirect test methods, electrolyte leak testing detects volatile components of the actually filled electrolyte. This makes it particularly suitable for quality testing of already filled and sealed lithium-ion and other metal-ion cells.
Direct Electrolyte Detection
Escaping solvent components are immediately detected.
Non-Destructive Testing
Intact cells can remain in the production process after testing.
Automated Series Processes
Chamber technology, handling, evaluation, and NIO sorting can be combined into a complete test process.
The result: a customized test system that combines cell quality, process reliability, and suitability for series production.
... and have your testing task evaluated
Advantages in Serial Production
Reliably test
filled cells
The method starts where many classic test methods reach their limits: after electrolyte filling and cell sealing. It does not just indirectly evaluate a possible leak path, but detects escaping electrolyte vapor.
Detect minute leaks
Under vacuum, volatile electrolyte components can escape from the cell through micro-leaks. A suitable analysis system detects these components even in very low concentrations.
Test all common cell formats
The test principle is suitable for: prismatic cells, cylindrical cells and button cells, pouch cells, lithium-ion and other metal-ion cells with liquid organic electrolyte.
Obtain objective good/bad decisions
The measurement provides a reproducible signal that is evaluated against a qualified limit value. Test programs, recipe management, and process data acquisition enable clear assignment to the respective cell type.
Test without additional test gas
The electrolyte components already present in the cell serve as the detection medium. No helium needs to be introduced into the fully sealed cell. This means the test does not interfere with the electrolyte filling process.
Automate test processes
From cell feeding to chamber loading and measurement, to marking and NIO sorting, the entire test process can be automated. Multi-chamber or batch concepts can increase throughput.
Typical Battery Cells and Applications
Pouch Cells
Detection of leaks at seal seams, current collector feedthroughs, and thermally or mechanically stressed areas. A flexible or contour-adapted chamber supports the cell during vacuum testing.
Prismatic Cells
Testing of housing joints, lid weld seams, filling openings, degassing and safety elements after filling and sealing.
Cylindrical Cells and Button Cells
Integral testing of fully sealed cells for leaks at crimps, lids, seals, and filling areas.
Possible Application Times
directly after electrolyte filling and sealing, after formation, after degassing and final sealing, before module assembly, as end-of-line testing, for random samples, failure analyses, and requalifications
Comparison of MACEAS Testing Methods
| Kriterium | Helium-Dichtheitsprüfung | Ultraschall-Dichtheitsprüfung im Wasserbad | Elektrolyt-Dichtheitsprüfung | Druckabfallprüfung |
|---|---|---|---|---|
| Besonders geeignet für | Sehr kleine Grenzleckraten und quantitative Serienprüfung | Erkennung und direkte Lokalisierung von Leckstellen | Befüllte und verschlossene Batteriezellen | Mittlere bis größere Grenzleckraten und Serienprüfungen |
| Prüfzeitpunkt | Komponenten- und Baugruppenfertigung | Bei druckbeaufschlagbaren, für das Wasserbad geeigneten Bauteilen | Nach der Befüllung und dem Versiegeln der Zelle | Komponenten- und Baugruppenfertigung |
| Leckstelle lokalisierbar | Ja, mittels Helium-Schnüffelprüfung | Ja | In der Regel nicht unmittelbar | Nein |
| Wasserbad oder Trocknung erforderlich | Nein | Ja | Nein | Nein |
| Besondere Stärke | Höchste Empfindlichkeit und objektiver Leckratenwert | Anschauliche Leckageortung | Prüfung mit dem tatsächlich austretenden Elektrolyt | Wirtschaftlich und gut automatisierbar |
When Pressure Testing and Helium Bombing Reach Their Limits
Pressure drop and differential pressure methods are economical and suitable for numerous production steps. However, for very small leaks, measurement results can be influenced by temperature, cell volume, deformation, and stabilization times. Furthermore, they do not provide direct evidence of escaping electrolyte.
Even so-called helium bombing is only of limited significance for liquid-filled cells. Helium can accumulate in the cell’s gas space, while leak points wetted with electrolyte are not reliably exposed. In contrast, direct electrolyte detection uses the escaping solvent itself as the detection medium.
The later in the production process testing is performed, the more important a method that evaluates the actually filled and sealed cell becomes.
Application Examples from Our Practice
Electrolyte Leak Testing of Prismatic Battery Cells
After filling and final sealing, the prismatic cells are automatically identified and placed in a component-specific vacuum chamber. During testing, the analysis system detects any escaping electrolyte components.
The test system combines:
- automatic cell feeding,
- reproducible positioning,
- vacuum testing,
- good/bad evaluation,
- traceability of measurement results,
- automatic NIO sorting.
By operating test chambers in parallel, evacuation, measurement, and discharge can be temporally overlapped. The system concept can initially be designed for one cell variant and later expanded to include additional formats or test modules.
Example System Concept
Prismatic Battery Cells
How Direct Electrolyte Leak Testing Works
Customized System Concept
Depending on cell format and production target, the test system consists of:
component-specific cell holder
rigid vacuum chamber or flexible pouch cell chamber
vacuum generation
electrolyte detection system
gross leak and contamination protection
automatic chamber cleaning or flushing
PLC control and test software
recipe and variant management
measurement data archiving and traceability
cell feeding and removal
NIO sorting
optional marking
interfaces to MES, master computer, or production line
MACEAS delivers not just a measuring device, but the complete, component-specific test process:
from cell handling to automated results processing.
From Test Task
to Finished Test System
MACEAS considers not only the detector but the entire production process – from the analysis of the battery cell to the integration of the finished test system.
Which leak test is right for your cell production?
Not every testing task requires direct electrolyte detection. For example, before filling, a helium test may be technically and economically more suitable. After filling, however, direct electrolyte detection offers the possibility to evaluate the finished cell under realistic conditions.
MACEAS analyzes the test time, the required sensitivity, and the production process, and from this develops the suitable test and automation concept.
... and discuss your requirements with us
Frequently Asked Questions
Application and Suitability
What is measured during electrolyte leak testing?
Volatile components of the electrolyte contained in the battery cell are measured, which enter the test chamber through a leak under vacuum. Depending on the electrolyte composition, the analysis system can be adapted to specific solvents or their characteristic mass signals.
Which cell formats can be tested?
When does the test take place?
Typical test times are immediately after filling and sealing, after formation, after degassing and final sealing, or at end-of-line.
Is the method non-destructive?
Yes, provided that the chamber, vacuum profile, and cell holder are correctly matched to the cell format. Especially for pouch cells, suitable support is necessary.
Can an electrolyte leak rate be directly converted into a helium leak rate?
Not exactly. The liquid leak rate depends on electrolyte composition, vapor pressure, wetting, cell internal pressure, and leak geometry. Displayed helium-equivalent values are therefore based on defined reference conditions.
How is the system protected against electrolyte contamination?
Can multiple cells be tested simultaneously?
Can the test be fully automated?
Does electrolyte testing replace helium testing?
Managing Director
Have your testing task evaluated
Whether feasibility study, manual test station, or fully automated series system: MACEAS develops the suitable system concept for your battery cells.
Together, we clarify cell format, electrolyte, test time, limit value, cycle time, and degree of automation, and derive the appropriate test process from this.
Leak Testing of Battery Cells with Direct Electrolyte Detection
Electrolyte leak testing is a specialized method for quality and safety testing of battery cells. It serves to detect minute leaks in already filled lithium-ion cells before electrolyte escapes, moisture penetrates, or safety-relevant consequential damage arises.
The method is particularly relevant in the manufacturing of pouch cells, prismatic cells, and cylindrical cells for electromobility, stationary energy storage, consumer electronics, and industrial battery systems.
Leak Testing of Battery Cells with Direct Electrolyte Detection
In direct electrolyte leak testing, the filled and sealed battery cell is placed in a test chamber. Under vacuum, volatile components of the electrolyte can escape from the cell if micro-leaks are present. These vapors are then detected metrologically, for example, with a quadrupole mass spectrometer or comparable sensor technology.
The advantage: It does not just test an abstract leak path, but the actual escape of relevant electrolyte components. This makes the method particularly suitable for fully filled cells where classic test gases can no longer be used or can only be used to a limited extent.
Good reasons for MACEAS
Classification in the Test Process
Electrolyte leak testing is primarily relevant for the later cell manufacturing process — i.e., after electrolyte filling and cell sealing. Before that, other methods are often used, such as helium vacuum testing or helium sniffing of cell housings, covers, cooling systems, or battery components. Expert sources also describe helium testing and direct electrolyte detection as different but complementary testing approaches in the battery environment.
What distinguishes MACEAS
and technologies
are our top priority
