By 2030, more than 100 million electric vehicles are expected to be on roads worldwide. To make e-mobility more sustainable for the future, nearly all manufacturers are focusing on increasing range and reducing charging times. A key area of development is high-performance battery cells.
A sealing provider supports manufacturers with solutions that improve the reliability of battery cells. These solutions not only contribute to longer lifespan but also offer greater design flexibility and advance cell design. Freudenberg Sealing Technologies has brought two products, Cell Caps and Cell Envelopes, to market maturity, which meet these exact requirements.
The Cell Envelopes are made from nonwoven fabrics that encase the cell stack and, like conventional films, protect the stack during assembly and electrically insulate it. They form a three-dimensional porous structure. The fibers themselves are permanently wettable for the electrolyte due to surface treatment. This reduces the risk of gas bubble entrapment during cell filling and ensures the stack remains wetted.
Functioning like a sponge
Thanks to their higher thermal conductivity, electrolyte-filled nonwoven fabrics offer better thermal management within the battery cell compared to films. Additionally, the wettable porous structure of the envelope – similar to a sponge – serves as an additional electrolyte reservoir. When compressed, the electrolyte is released, which is especially beneficial during the aging process of the cells when additional electrolyte is needed.
As a compression element, envelopes made of thicker nonwoven layers can partially compensate for the thickening of the cell stack within the cell. This allows the compression elements between cells to be designed narrower. At the same time, the pressure distribution within the cell stack becomes more uniform, reducing the risk of dendrite formation and lithium plating.
Manufactured according to automotive standards
To increase the safety and performance of electric vehicles, Freudenberg Sealing Technologies offers customer-designed Cell Caps, developed in collaboration with cell manufacturers. These caps integrate all required functions, including rupture discs that release gases in the event of a thermal runaway. Cell Caps are produced locally for the regional market with the lowest possible CO2 footprint and in compliance with automotive standards such as IATF 16949.
“In these customer projects, we combine state-of-the-art materials with intelligent design, as well as our expertise in sealing technology and technical plastics with our knowledge in stamping technology. This allows us to set new standards to ensure perfect sealing and long life for the Cell Caps,” says Giulia Richard, Global Marketing Director at Freudenberg Sealing Technologies.
Compatible with various electrolytes
The Cell Caps are gas-tight tested and maintain this ability throughout the battery's life, ensuring optimal performance under various operating conditions, minimizing the risk of gas leaks, and enhancing safety. Additionally, the Cell Caps exhibit mechanical resistance to peak loads and fatigue.
Their compatibility with different electrolytes, potentially external cooling fluids, and gases enables seamless integration into various electric vehicle systems. All materials used are electrochemically tested.
“Mobility is changing, and Freudenberg Sealing Technologies is keeping pace. As a market leader in technology, quality, and service for the automotive sector, we have the expertise to develop and manufacture innovative, forward-thinking products for the mobility of the future,” emphasizes Ulrich Huth, President of Automotive Sales at Freudenberg Sealing Technologies.
