The FFU has become a mission-critical infrastructure throughout the new-energy sector, especially in lithium-ion battery and photovoltaic (PV) cell manufacturing, where sub-micron cleanliness, ultra-low humidity and strict electro-static discharge (ESD) control determine product safety, performance and yield. The following sections provide an in-depth analysis of FFU deployment in these processes.
I. Core Environmental Requirements in New-Energy Manufacturing
1. Ultra-High Particulate Cleanliness
- Lithium-ion batteries: Metal or polymer particles ≥ 1 µm trapped between electrode and separator can create internal micro-short-circuits, leading to self-discharge, heat build-up and thermal runaway.
- PV cells: Dust on wafer surfaces causes coating defects and reduces photoelectric conversion efficiency.
2. Low Moisture (Low Dew-Point) Control
- Lithium salts (e.g. LiPF₆) hydrolyse in the presence of moisture, generating corrosive HF and irreversible capacity fade. Electrode coating, drying and electrolyte filling therefore require dew points ≤ –40 °C, often –50 °C.
3. Electro-Static Discharge (ESD) Control
- Separators and PV films are high-dielectric materials that easily accumulate charge. ESD attracts particles, disturbs process equipment and can ignite flammable solvents.
4. Airborne Molecular Contamination (AMC) Control
- Acid gases, bases and VOCs adsorb on active materials, degrading coating adhesion and interfacial stability.
II. Technical Roles of FFU in New-Energy Production
1. Creation & Maintenance of Vertical Laminar Flow
- FFUs are ceiling-mounted at high coverage ratios above coating, calendering, slitting, stacking/winding and electrolyte-filling lines.
- A downward, non-turbulent air blanket continuously sweeps particles away from electrode foils and separators.
- The air supplied is pre-dried by desiccant de-humidifiers; FFU housings are gasket-sealed to prevent ingress of ambient moisture.
2. Achievement of ISO 5–7 (Class 100–10 000) Clean Zones
- Cell assembly halls typically target ISO 7; critical processes (coating, winding) require ISO 6 or ISO 5.
- HEPA H13/H14 (99.995 % @ 0.3 µm) is standard; ULPA U15/U16 filters are adopted where ≤ 0.1 µm control is mandatory.
- Zero-leak gel-seal or fluid-seal designs are validated by PAO/DOP scan-testing of every unit.
3. Anti-Static & Explosion-Proof Design
- In solvent-rich drying and filling rooms, FFU casings and perforated face plates are manufactured from conductive polymers or receive anti-static powder coating (surface resistivity 10⁶–10⁹ Ω).
- EC motors and junction boxes installed in Zone 1/21 or Zone 2/22 areas carry ATEX or GB-Ex certification, eliminating spark ignition sources.
4. Platform for Chemical Filtration (Optional)
- Chemical filter modules (activated-carbon or functionalised media) can be integrated into the FFU stack to remove SOx, NOx, NH₃ and amines, protecting sensitive electrode and photo-active layers.
III. Engineering Specification Checklist for New-Energy FFUs
1. Filter Efficiency: HEPA H13 minimum; ULPA U15–U16 for ISO 5 or better.
2. External Static Pressure: ≥ 120–150 Pa to overcome added resistance of chemical filters and airflow equalisation membranes while maintaining rated airflow.
3. Motor & Electricals: Electronically Commutated (EC) motors for high efficiency, low heat pick-up and stepless speed control; Ex-certified versions for hazardous areas.
4. Materials & Finish: SUS 304 or low-carbon zinc-coated steel with anti-static, corrosion-resistant powder coating; all internal surfaces low-shedding and smooth (Ra ≤ 0.8 µm).
5. Leak-Tightness: 100 % factory PAO scan plus photometer test; gel-seal knife edge flatness ≤ 0.5 mm.
6. Monitoring & Control: RS-485 / Modbus-RTU or TCP/IP for group control; integration into FMCS/BMS for remote speed adjustment, differential-pressure alarms and filter-life prediction.
Conclusion
In new-energy manufacturing the FFU has evolved from a simple air-cleaning device into a process-enabling life-line:
- For lithium-ion batteries it is the safety guardian, preventing particle-induced internal shorts while sustaining ultra-dry atmospheres.
- For PV cells it is the efficiency protector**, eliminating dust that degrades conversion efficiency.
Any compromise in FFU performance-whether in filter efficiency, housing leakage, dew-point integrity or ESD control-translates directly into elevated safety risk, yield loss and field failures. Consequently, plant designers must select high-reliability FFUs that combine high static-pressure capability, HEPA/ULPA filtration, anti-static construction, optional explosion-proof certification and intelligent network control.
