Inficon Touts Improved Battery Leak Testing

Problems caused by water and moisture leaking into a high-voltage lithium-ion electric vehicle battery are relatively rare.

But when they happen, the consequences can be dramatic—or even fatal.

In worse case scenarios, such leaks can trigger a fire or cause an explosion. At the very least, leaks can deteriorate performance and/or reduce the life of a battery, notes testing specialist Inficon.

The Switzerland-based company estimates that about 5% of the billions of lithium-ion battery cells produced each year for use in electrified vehicles, consumer electronic products and medical devices have undetected leaks.

New Process

Inficon says it has developed a new testing method that can identify leaks 1,000 times smaller than currently possible.

Inficon ELT3000 leak detector (Image: Inficon)

Currently, most battery companies use helium in a vacuum chamber to test for leaks. But such tests are conducted with empty hard-case battery cells prior to electrolytes being injected into the batteries, which can result in small leaks where the hole to inject the electrolytes is sealed.

Inficon claims its system is the only one that allows automakers and battery suppliers to accurately test battery cells already filled with electrolyte.

How It Works

Battery cells are placed into a vacuum chamber connected to Inficon’s new ELT3000 leak-detection unit with a mass spectrometer. The tests occur before the individual cells are packaged into a battery pack.

The battery system is based on a technology that has long been used to detect refrigerant leaks in appliances such as air conditioners and freezers.

In battery cells, the spectrometer can detect small molecules coming through a hole or defect. Such precise testing is needed to ensure moisture can’t seep into the battery, explains Thomas Parker, Inficon’s North American automotive sales manager.

In addition to driving through flooded streets or backing a boat trailer into the water, Parker says batteries are susceptible to leaks from humidity during normal operation.

The new test can be used for all types of common electrolyte solvents. It also can be used for the three main types of lithium-ion EV batteries: hard-cased prismatic, cylindrical cells and softer pouch cells.

What’s Next?

Inficon is introducing the technology, which took about four years to develop, this month for testing prismatic and cylindrical cells.

Capabilities for pouch cell testing will be added in late 2020 or early 2021. Pouch cells are more prone to leakage because they are pressurized, Parker notes.

The supplier hopes the new spectrometer eventually leads to a standardized process to help improve the reliability and safety of EV batteries.

 “As more EV cars populate roads, there will be more fires if we don’t address battery leakage problems,” Parker warns.

Citing industry figures, Inficon estimates the global market for battery cells will more than double from about $44 billion this year to nearly $95 billion in 2025. Annual lithium-ion battery-cell production is expected to more than triple from 280 gigawatt hours this year to 970 GWh in 2025, then jump to 2,600 GWh by 2030, Parker says.

More information about Inficon’s system is available in a recent SAE paper titled “Methods for Leak Testing Lithium-Ion Batteries to Assure Quality with Proposed Rejection Limit Standards.”