How moisture infiltrate Lithium-ion battery Packs?

Moisture on Lithium-ion Cells

 Moisture can infiltrate lithium-ion battery packs through several primary mechanisms:

• Condensation: When warm, humid air encounters a colder surface within the battery pack (such as the cells or enclosure), the moisture in the air transitions into liquid water. This phenomenon is particularly prevalent in environments where temperature and humidity levels fluctuate significantly.

• Leaks: Imperfections in the battery pack's casing, including cracks, faulty breather plugs or inadequate seals, can create pathways for external moisture to penetrate. These vulnerabilities can arise from manufacturing defects, physical damage during transport or usage, or the natural wear and tear associated with the battery pack's lifespan.

• Coolant Leaks: In battery packs equipped with liquid cooling systems, leaks within the coolant lines can introduce moisture into the pack. Coolants often contain water or possess hygroscopic properties, meaning they readily absorb moisture from the surrounding air.

• Manufacturing Process: While less frequent, moisture can be inadvertently introduced during the battery pack's manufacturing process if proper drying and sealing procedures are not strictly adhered to.

The presence of moisture within a lithium-ion battery pack can have detrimental consequences:

• Diminished Performance: Moisture can corrode the internal components of the battery pack, leading to an increase in internal resistance and a subsequent reduction in energy capacity.

• Safety Hazards: Moisture can interact chemically with the battery's constituents, generating heat and potentially culminating in fires or explosions.

• Accelerated Aging: Moisture can expedite the aging process of the battery pack, resulting in a shorter overall lifespan.

To mitigate moisture ingress, manufacturers employ a variety of strategies:

• Hermetic Sealing: Utilizing high-quality seals and gaskets to establish a moisture-tight barrier.

• Desiccants: Incorporating moisture-absorbing materials within the battery pack to minimize the impact of any residual moisture that may enter.

• Regular Inspections: Conducting periodic inspections to identify and address any potential leaks or damage.

• Controlled Manufacturing Environments: Maintaining a low-humidity environment throughout the manufacturing process.

By comprehending the pathways through which moisture can infiltrate lithium-ion battery packs and implementing effective preventative measures, manufacturers and users can contribute to ensuring the safety, performance, and longevity of these critical components.