Cell Caps 2 is a next-generation battery cell cap technology for prismatic and cylindrical cells developed by Freudenberg Sealing Technologies. The new technology will be presented at The Battery Show Europe, which will take place in Stuttgart, Germany, on June 9-11, 2026.
Cell caps occupy a considerable portion of the cell volume – space that both the manufacturer and the customer would ideally prefer to use for energy storage to power the application. Yet, the function of the cell cap is undeniably demanding: it must reliably seal the cell chemistry off from the environment while simultaneously enabling the safe and reliable filling of the cell with electrolyte. Cell caps must facilitate fast charging, incorporate safety mechanisms in the event of thermal runaway and contribute significantly to the mechanical integrity of the cell.
Fewer parts, more energy
The core of the Cell Caps 2 development consists of integrating the terminal in molded rubber into the base plate of the cell cap.
To fix the terminals within the cell cap, liquid elastomer is injected into the gap between the poles and the cap base plate. The elastomer permanently bonds these components together, providing excellent gas tightness, mechanical robustness and electrical insulation – all with a minimal number of parts and very low mass, which can significantly reduce the overall battery weight.
The next-gen technology reduces the height of the cell cap by up to 30%, depending on customer requirements, enabling higher energy capacity and longer operating time.
Freudenberg is currently working on the mass production of a round cell cap that fully leverages all the advantages of the next-generation technology. The cell caps can be manufactured using the same technology as valve stem seals, which Freudenberg produces in the millions.
Expanded safety portfolio
As well as its battery cell caps, the company will also be showcasing a range of other technologies. Its cell-to-cell barrier range has been expanded to include additional thicknesses and material variants, ranging from compact multi-layer designs with foam or elastomer compression layers to UL94-V0-certified heat shields with adhesive backing.
These can be tailored to meet specific requirements for thermal resistance, mechanical stability, durability, compression behavior, cell swelling tolerance and compatibility with different cell chemistries, including NMC and LFP. The company is also displaying venting foam mats, which are positioned above battery cells and are designed to help protect neighbouring cells in the event of thermal runaway.
A demonstrator at the show will illustrate how the company’s busbar seals compensate for thermally induced changes in length and ensure a durable seal against media and the environment. At the same time, they permit defined movements of the busbar within the system. In addition, the company will also offer a preview of its advanced battery cooling program and its growing portfolio of components for heat pumps in electric vehicles.
“Whether it’s cell caps, thermal barriers or thermal management, we consistently turn standard components into high-performance solutions – exactly what our customers need across automotive and industrial applications,” said Andrea Giordano, head of battery cell caps and thermal barriers at Freudenberg Sealing Technologies’ Pinerolo site.
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