Lithium Battery & EV Manufacturing in Vietnam: Cleanrooms for Gigafactories

VinFast is building a lithium-battery plant in Hà Tĩnh, Pegatron is expanding its line in Hải Phòng, and many other businesses are riding the wave of investment into electric vehicles and stationary energy storage. Unlike ordinary electronics cleanrooms, lithium-battery plants demand an extreme requirement: an absolute dry room with a -40°C dew point. This article reviews the industry-specific cleanroom architecture.

1. Why do lithium batteries need a special dry room?

Lithium-ion batteries contain metallic lithium — which reacts strongly with water vapour. Even small amounts of moisture during cell assembly can cause:

• Chemical reactions producing LiOH and Li₂O — corroding the cell structure.
• Hydrogen generation — risk of fire or explosion.
• Reduced capacity and life — premature cell failure after few cycles.
• Cell "swelling" incidents — dangerous to end users.

Industry standards for battery cells require:

• -40°C dew point (equivalent to ~0.13 g of water vapour per m³) in cell-assembly rooms.
• -60°C dew point for electrode-handling rooms after drying.
• For comparison: ambient air at 30°C and 60% RH has a dew point around +22°C, containing 18 g/m³ of water vapour — 140 times the lithium-battery limit.

2. Lithium-battery plant zoning

A complete production line has 6 main zones:

Zone 1 — Electrode coating

• Coats graphite (anode) or NMC/LFP (cathode) mixtures onto copper/aluminium foil.
• Requirement: Class 10,000 (ISO 7), low RH 20-30% is sufficient.
• Filter train: Pre G4 + Medium F8 + HEPA H14.

Zone 2 — Calendering & slitting

• Compresses electrodes to densify them, then slits to size.
• Requirement: Class 10,000, RH 10-20%.
• Filter train: same as Zone 1.

Zone 3 — Drying

• Vacuum-oven drying at 100-120°C to remove NMP and water.
• Requirement: room with NMP (solvent) recovery system.

Zone 4 — Dry room (cell assembly)

• Winds the jelly roll, puts it into a steel/aluminium can, welds the tabs.
• Requirement: Class 10,000 + -40°C dew point (the biggest distinguishing factor).
• Filter + humidity handling: Pre G4 + Medium F8 + HEPA H14 + desiccant dehumidifier (silica-gel rotary).

Zone 5 — Electrolyte filling

• Pours LiPF₆ in organic solvent (EC/DMC/EMC) into the cell.
• Requirement: Class 10,000 + -40°C dew point, with solvent-vapour management.

Zone 6 — Formation & aging

• Initial low-current charging to stabilise the cell structure.
• Requirement: room with thermal management and fire-safety systems.

3. Dry room — distinctive architecture

The dry room is the soul of the battery plant. Unlike ordinary cleanrooms, dry rooms feature:

a. An ultra-airtight envelope

• 100 mm PU sandwich panels with 304 stainless-steel skins on both sides.
• All joints sealed with specialised silicone.
• Double-leaf airlock doors with twin gaskets and pressure sensors.

b. A two-wheel desiccant dehumidification system

• Wheel 1 (silica gel) — dehumidifies incoming fresh air from 18 g/m³ to 1 g/m³.
• Wheel 2 (zeolite) — further from 1 g/m³ down to 0.1 g/m³ (-40°C dew point).
• The wheels rotate continuously; part of each wheel is reactivated with hot air at 120-140°C to release adsorbed water.

c. Ultra-dry supply AHU

Pre G4 → Medium F8 → Desiccant wheel 1 → Deep-cooling coil → Desiccant wheel 2 → Reheater → HEPA H14 → Supply to room

d. High differential pressure

• Dry room +50 Pa relative to surroundings — ensures moist air does not leak in.
• Intermediate airlock +25 Pa.

e. Dry-room entry procedure

• Personnel: wear a dry bunny suit (no sweat); pass through an airlock with dry-air blowers.
• Materials: pass boxes with vacuum dehumidification before the inner door opens.

4. Heat load and energy

Dry rooms are very energy-intensive:

• Desiccant dehumidification: 5-10 kW per 100 m³/h of supply.
• Deep-coil cooling: 3-5 kW per 100 m³/h.
• Reheat after the wheels: 1-2 kW per 100 m³/h.
• Total HVAC: 50-80 kWh/m² per month — 5-10× a normal cleanroom.

Therefore:

• Minimise dry-room volume.
• Use heat recovery between exhaust and supply.
• Use AGVs and robots to reduce headcount in the room → less heat and moisture from people.

5. Filters for lithium-battery rooms

Dry-room filters have special requirements:

• Dry filter media — no media with water-based additives.
• 304/316 stainless-steel frames — resist solvent vapours.
• Silicone gaskets that endure long-term dryness without hardening.
• Dry-panel Pre Filters — no batting rolls with water-based antifungal additives.

6. Fire and explosion safety

Lithium batteries and electrolyte solvents are flammable. Special fire-safety design:

• Hydrogen-gas sensors in every zone.
• Photoelectric smoke detectors (safer than ionisation types in solvent atmospheres).
• Aerosol fire suppression (Stat-X, FirePro) rather than sprinklers — does not react with lithium.
• Isolation rooms for cell testing — cells inside blast-resistant chambers.
• Emergency ventilation exhausts smoke and toxic gases via HEPA + tall stack.

7. Vietnamese case: VinFast Gigafactory in Hà Tĩnh

VinFast is investing in the VinES battery plant at Vũng Áng, Hà Tĩnh, with an initial capacity of around 5 GWh/year, with technology partnership from Gotion High-tech. The plant features:

• LFP cell production lines for EVs and stationary storage.
• A dry room of tens of thousands of m² at -40°C dew point.
• An HVAC + desiccant system rated in tens of MW.
• Dedicated fire-safety system for lithium hazards.

8. Opportunities for Vietnamese businesses

Batteries and EVs will be the next big FDI wave after semiconductors. Vietnamese suppliers can win in:

• Materials: graphite, copper, aluminium, steel cans.
• Hardware: bolts, connectors, high-voltage cables.
• Structures: battery-pack frames, armour casings.
• BMS and BMU modules — relatively simpler assembly.

All of these require ISO 7-8 cleanrooms with HEPA H13/H14 filtration.

9. Design considerations for dry rooms

• Design margin for northern Vietnam's humid "nồm" days (outdoor RH >95%).
• Panel-leak testing with smoke generators before commissioning.
• Dew-point sensor calibration every 3 months.
• Stock HEPAs and desiccant wheels — overseas lead times typically 8-16 weeks.
• Preventive-maintenance programme — one day of dry-room downtime can cost billions of VND in re-drying energy.

Conclusion

Lithium-battery and EV manufacturing demands the most specialised cleanrooms — not just clean from particles but ultra-dry. Investing properly in the dry room, desiccant systems, dedicated HEPAs, and explosion safety is the prerequisite for Vietnam to join the global EV and new-energy supply chain.

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About Green Filter

Green Filter supplies HEPA H13/H14, Medium F8/F9, and stainless-steel-framed Pre Filters suitable for dry rooms and lithium-battery cleanrooms. Products are manufactured from dry materials without water-based additives, ensuring no secondary moisture release in a -40°C dew-point environment.

📞 Contact Green Filter for filter consulting for your lithium-battery / EV project: [insert hotline / email / website]

See also: Cleanrooms for electronics & semiconductors · Bắc Ninh - Bắc Giang industrial parks · Energy savings for cleanrooms.