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07.10.2026 | Story

What you need to know

Renewable Energies Energy Generation

By 2030, 80 percent of the electricity produced in Germany is expected to come from renewable energies. In the “intelligent electricity grids” (smart grids) of the future, energy storage systems are an essential means of absorbing peak loads and ensuring flexibility in terms of space and time. Safety standards are indispensable in this area so that decarbonization can also function across borders. Which legal framework conditions apply where? Here is an overview that does not claim to be exhaustive:

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Standards and Guidelines

Which standards and guidelines apply to seals in the process chains for battery energy storage systems?

DIN (German Institute for Standardization)

German Standardization Roadmap Energy Storage Version 2; provides an overview of the standardization of energy storage systems

WEBSITE  ›

GB 44240-2024

Chinese standard, secondary lithium cells and batteries for electrical energy storage systems – safety requirements, English version

WEBSITE  ›

EU 2023/1542

EU battery regulation on batteries and waste batteries; component of the European Green Deal for the assessment, standardization and legal regulation of battery types and associated obligations in the EU countries

WEBSITE  ›

DIN EN IEC 62619 VDE 0510-39:2023-08

Secondary cells and batteries with alkaline or other non-acid electrolytes; safety requirements for secondary lithium cells and batteries for use in industrial applications

WEBSITE  ›

DIN EN IEC 62933-5-2:2025-08

Draft – Electrical energy storage systems (EES systems) - Part 5-2: Safety require ments for grid-integrated EES systems – electrochemical systems

WEBSITE  ›

NFPA 855 (National Fire Protection Association)

U.S. safety regulations for the installation of energy storage systems

WEBSITE  ›

UL9540

Basic safety standards for energy storage systems; safety standards for electrical energy storage technologies, including lithium-ion batteries, lead-acid batteries, fuel cells, flywheels and other electrochemical energy storage systems

WEBSITE  ›

Conclusion

Fabien Phong and Marcel Schreiner

Fabien Phong and Marcel Schreiner

Battery energy storage systems are a critical component of global energy infrastructure. The market for BESS is expanding rapidly: global installed capacity exceeded 300 GWh in 2025, representing a 51% increase over the prior year. This growth is directly linked to the expansion of wind and solar generation capacity, where BESS provides the flexibility and dispatchability that variable renewable sources cannot offer on their own.

For this growth to be safe, reliable, and compliant across jurisdictions, the safety-relevant components at the heart of every BESS — seals, thermal barriers, pressure equalization elements, and module barriers — must meet demanding and often conflicting requirements: extreme temperature resistance, long service life, chemical compatibility, mechanical robustness, and compliance with an evolving international regulatory landscape.

Freudenberg Sealing Technologies addresses these requirements through continuous material development, global testing infrastructure, and close collaboration with BESS manufacturers from the earliest design stages. Key innovations include the Quantix® Ultra 94-2 thermal barrier system for module-level thermal runaway containment, the DIAvent® pressure equalization valve for controlled venting, and a comprehensive portfolio of EPDM and FKM sealing solutions qualified for the full BESS operational temperature range.

This white paper provides the technical foundation for understanding BESS sealing requirements. Freudenberg Sealing Technologies welcomes feedback and questions to continue developing this series.

Marcel Schreiner
Global Segment Director Energy

Fabien Phong
Global Key Account Manager, Segment Energy

Checkliste

A checklist: What information do I need to select seals for use across the process chains of battery energy systems?

With this checklist, we want to support you in systematically determining a variety of key parameters required for optimal seal selection.
We wish you every success in working with our checklist!

Application location: Where is the seal used?

  • battery cell housing
  • module enclosure
  • cooling circuit
  • plug connectio
  • power electronics housing
  • thermal management system

Dimensional requirements: What are the dimensions, tolerances, and shape specifications?

  • inner diameter
  • cross-section
  • groove dimensions
  • compression ratio

Sealing surface condition

  • surface finish
  • roughness (Ra)
  • hardness

Media contact: What media does the seal come into contact with?

  • electrolyte type
  • coolant composition
  • lubricants
  • cleaning agents
  • gases

Environmental exposure: Are there requirements for resistance

  • UV radiation
  • ozon
  • oxidation
  • saltwater

Temperature range

  • minimum and maximum temperatures
  • which limit values will likely cause malfunctions? (include transient conditions and thermal runaway scenarios)

Pressure conditions

  • operating pressure
  • pressure peaks

Mechanical loads during operation or transport

  • mechanical forces
  • vibrations
  • shock loads
  • oscillations act

Electrical properties

  • electrically insulating
  • electrically conductive
  • EMI-shielding

Aging and service life: What are the aging and service life requirements for the seals?

  • target lifecycle in years
  • expected charge/discharge cycles

Material preferences or exclusions

  • material preferences
  • known incompatibilities
  • regulatory restrictions on specific material classes

Standards compliance: Which industry-specific norms, standards, or approvals must the seal meet?

  • UL 94
  • IEC 62619
  • NFPA 855
  • UL 9540
  • regionale standards
  • others

Quantity and logistics

  • batch quantities
  • delivery times
  • packaging formats
  • traceability
  • documentation requirements
  • Standards
    Batteries News Daily news and market information on lithium-ion batteries WEBSITE
    ESS News, powered by PV Magazine Global demand for battery storage systems rises by 51% in 2025; installed capacity exceeds the 300 GWh mark WEBSITE
    Battery Recycling Regulations Recycling requirements for sealing materials; limits for material recovery, valid since 2024/2025 WEBSITE
    The Battery-News One of the leading sources of information in the world of batteries; includes expert articles and industry news WEBSITE
    Blackridge Research & Consulting Top 5 Largest Upcoming Battery Energy Storage Projects in the World (2026) WEBSITE
    The Hindu BusinessLine Comprehensive market analysis and reporting on economic developments in India – BESS News: Latest & Breaking News on BESS WEBSITE
    CNESA – China Energy Storage Alliance China Energy Storage Alliance: China’s largest nonprofit organization for promoting and developing the energy storage industry WEBSITE
    Energy Storage News Industry news for professionals; includes events and academic research findings WEBSITE
  • Glossary
    BESS Battery energy storage system — a system of electrochemical cells that stores electrical energy for later use at grid or commercial scale
    BMS Battery management system — electronic system that monitors and controls battery cell voltages, temperatures, and state of charge
    DIAvent® Pressure equalization element — proprietary Freudenberg Sealing Technologies valve that allows controlled gas venting while maintaining ingress protection
    EPDM Ethylene propylene diene rubber — synthetic elastomer with excellent resistance to water, steam, ozone, UV radiation, and heat; commonly used in BESS housing gaskets and static seals
    FKM Fluororubber — high-performance elastomer with superior chemical resistance to hydrocarbons, fuels, and aggressive fluids; used in BESS components with electrolyte or coolant exposure
    LFP Lithium iron phosphate — a lithium-ion cell chemistry known for thermal stability and long cycle life; increasingly dominant in stationary BESS
    NMC Lithium nickel manganese cobalt oxide — a lithium-ion cell chemistry with high energy density; used in premium BESS and EV applications
    Quantix® Ultra 94-2 Proprietary Freudenberg Sealing Technologies thermal barrier material meeting UL 94 V-0 fire resistance classification; used in module and system-level thermal runaway containment
    Thermal barrier A component designed to impede heat transfer and contain thermal runaway propagation between battery cells or modules
    Thermal runaway An uncontrolled, self-sustaining exothermic reaction within a battery cell caused by overheating, overcharging, or physical damage; temperatures can exceed 1,200 °C
    Vessel-to-Grid A system in which a ship's battery provides shore-side power during port operations, reducing emissions from diesel auxiliary engines
    UL 94 Underwriters Laboratories flammability standard for plastic materials used in devices and appliances; V-0 is the most stringent classification

Requirements for seals and safety-critical components in large-scale battery storage systems

Which legal frameworks apply where?

Further information
Renewable Energies Energy Generation
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