Dry room handling of moisture-sensitive battery materials
Battery materials such as lithium salts, cathode active materials and electrolyte components are extremely moisture-sensitive. Even brief exposure to ambient air with a dew point of -20°C can lead to surface degradation, capacity loss and safety risks. Dry room bulk handling is therefore a core discipline in every GWh-scale battery factory.
What is a dry room and why is it necessary?
A dry room is a production space with a controlled low dew point, typically between -40°C and -60°C. At this moisture level, the relative humidity is so low that lithium-containing materials do not react with atmospheric moisture. Without a dry room, lithium would react with H₂O and O₂, causing HF formation, heat generation and capacity loss.
Dry rooms are expensive to build and maintain (energy consumption for dehumidification is significant). Every opening of the space — for material supply, discharge or maintenance — poses a risk of moisture ingress.
Challenges in bulk handling within the dry room
Standard bulk handling equipment is not designed for dry room environments. The specific requirements are:
- No mechanical seals with grease or oil: standard lubricants can evaporate or degrade at extremely low moisture levels
- Gas-tight connections: any leak introduces humid outside air into the process installation
- Dry cleaning: CIP with water is excluded — cleaning takes place dry (compressed air, vacuum) or with solvents
- Antistatic design: dry air increases the static charge on powders and equipment
- Compact installations: dry room space is costly — equipment must be as small as possible
Big bag discharge in the dry room
Big bags containing cathode material or lithium salts are often filled and transported outside the dry room. On entry into the dry room, the bag must be connected without breaking the dry room atmosphere. Solutions:
- Airlock: the big bag passes through an airlock that is pre-dried to the required dew point
- Contained connection via AAS/LAS: the bag is connected via a dust-free coupling already present in the dry room wall
- Endless liner system: the liner acts as a moisture barrier — the material is enclosed in PE until the moment of use
Pneumatic transport: dry gas as the transport medium
Pneumatic transport in the dry room uses dry compressed air or nitrogen (N₂) as the transport gas. The gas must be dried to the same dew point as the dry room. Leak points in the transport system are critical: even small leaks can introduce moisture locally. Hecht's gas-tight transport lines with contained rotary valves are designed for this.
Dosing in the dry room
Dosing screws and valves in dry room environments are built without standard sealing materials that absorb moisture. Weighing decouplers are dry-certified. The electrical components (frequency drives, load cells) are placed outside the dry room or built in a dry-room-compatible housing.
Maintenance and cleaning
Preventive maintenance in dry rooms requires planning: every maintenance entry temporarily raises the moisture level. Hecht supplies installations with minimal maintenance needs and maximum accessibility from outside (dry room wall pass-throughs for service access without entering the dry room).
Conclusion
Bulk handling in the dry room requires specially designed equipment that withstands extremely low moisture levels, is antistatic and dry-cleanable. Hecht Technology designs and supplies complete bulk handling systems for dry room environments in battery production.
More info: Complete guide to bulk handling in the battery industry.