require dry cleanrooms, particularly at higher densities and micro-miniaturisation where airborne particles become even more important. Cleanroom and Dry cleanroom A properly designed dry cleanroom is firstly a “Clean Vapour Shield”. This is a vapour-tight cleanroom envelope to minimise moisture and outside airborne particle infiltration. Dedicated PALs and MALs, i.e. air locks for personnel entry/exit and material air locks for raw material and equipment movement control, are used to manage the routine passage of staff and materials. These are typically interlocked, and access controlled with swipe cards. Floors provide a vapour barrier that is static dissipative and, in some areas, conductive in order to eliminate static electricity as part of Fire and Safety control. These facilities require fire separation and segregation, and come in different room heights to suit process requirements and mini-environments. MALs and PALs must be kept at positive pressure to prevent contaminant infiltration and dry cleanrooms require airborne particle filtration, typically to meet ISO Class 6, 7 or 8 levels, according to ISO 14644-1 cleanroom standards, depending on the exact manufacturing process requirements.
process layouts is of critical importance in the design of the dry cleanrooms as the very nature of the manufacturing process generates contamination, both particles, gases and moisture.
Moisture Control
The key metric in moisture control is the dew point— the temperature at which water vapour in ambient air starts to condense. The lower the dew point, the lower the water vapour content in the air. Even small amounts of moisture in the air can affect the integrity and compromise the quality of the finished EV battery. This can impact anything from the cell performance to the lifetime of the battery. The generally accepted dew point for lithium battery production is below -40°C (< 1% relative humidity), and as low as -70°C with new battery chemistries that are more moisture sensitive. While traditional Glove boxes can be used for small-scale R&D laboratories, high-volume manufacturing requires large Clean & Dry rooms, with precise environmental control along with dedicated mini environments as cell production lines. The key to reach the necessary dew point for high- volume production is in using efficient dehumidification technology designed specifically to create these specialist Clean & Dry room controlled environments.
Careful consideration of airflow patterns around the
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