Reversible Degassing Valve for Vehicle Lithium-Ion Battery Systems
Freudenberg Sealing Technologies developed a profiled metal spring mechanism to manage thermal runaway through adjustable trigger pressure and rapid gas venting.
www.freudenberg.com
As energy densities in modern electric vehicle batteries increase, managing thermal runaway requires rapid gas evacuation mechanisms. Freudenberg Sealing Technologies introduced a degassing element designed to release sudden gas volumes while maintaining the physical isolation of the battery housing. The technology, which addresses thermal escalation in individual battery cells, was presented at The Battery Show North America in 2025.
Mechanical Actuation and Reversible Sealing
Traditional burst disks rupture under overpressure but remain open, allowing subsequent oxygen ingress and preventing non-destructive testing after installation. Instead of a conventional elastomeric umbrella or single-use burst disk, the new component utilizes a profiled metal spring. When internal pressure reaches a pre-configured threshold, the valve achieves instantaneous full-aperture opening rather than gradual expansion. This mechanism expels hot gases rapidly, mitigating further pressure escalation within the battery pack. Following depressurization, the spring autonomously reseals the opening, restricting ambient oxygen from flowing into the battery casing. This reversible operation secures the internal environment after a thermal event and allows manufacturers to perform non-destructive end-of-line pressure testing on fully assembled battery packs.
Technical Specifications and Integration Parameters
The unit achieves an emergency degassing rate exceeding 190 liters per second at a differential pressure of 300 mbar, representing a 2.5-fold flow increase compared to the company's previous high-flow elastomeric valves. Activation pressure is configurable between 50 and 200 mbar. The component footprint measures 86 by 86 millimeters with a constrained installation height of 12.1 millimeters. It carries UL94 V0 flammability certification and meets IPX9K and IP6KX ingress protection standards against water and dust. Installation options include a standard M6 bolt, alongside available clip or bayonet mounts. An integrated PIP seal accommodates housing surface irregularities of up to 0.2 millimeters to maintain structural sealing.
Operational Impact
Daniel Uhl, Head of Product Management at Freudenberg Sealing Technologies, indicated that the mechanism addresses the limitations of single-use venting solutions by consolidating high flow capacity, adjustable trigger pressure, and autonomous resealing into a single unit, allowing engineers to improve safety and operational parameters in battery development.
Additional Context: This section details technical specifications and competitive benchmarking not included in the original product announcement.
In the broader battery degassing sector, thermal runaway management typically relies on either single-use burst disks or dual-stage elastomeric valves. Components engineered by companies such as Gore, Eaton, and Donaldson frequently utilize ePTFE membranes for continuous pressure equalization, paired with an active mechanical override for emergency venting. While burst disks offer unrestricted gas flow during cell failure, their inability to reseal permits atmospheric oxygen to fuel internal battery combustion. Elastomeric umbrella valves provide resealing capabilities but often encounter flow rate limitations at lower differential pressures. By achieving 190 liters per second at 300 mbar within an active resealable architecture, the profiled metal spring design addresses the functional gap between high-volume rupture disks and standard reversible elastomeric valves.
Edited by an industrial journalist, Lekshman Ramdas, with AI assistance.
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