Meaning
Adhesives and heat-sealed polymer interfaces can separate from their metallic substrates over time. For lithium-ion cells in pouch formats, seal delamination is a serious failure mode that compromises the hermetic integrity of the cell housing. This allows electrolyte to leak out and moisture to enter the cell.
Degradation Process
Moisture acts to weaken the chemical bond between the polymer and the metal surface. In a pouch cell, seal delamination can also be accelerated by chemical attack from hydrofluoric acid in the electrolyte. High temperatures or physical stresses from cell swelling put additional tension on the sealed edges.
This tension causes the polymer and metal layers to pull apart.
Sourcing Consequence
Sourcing teams analyze the rate of adhesive failure when evaluating different cell suppliers. Sourcing a cell that is prone to seal delamination can lead to high failure rates in the field, resulting in expensive product recalls. Procurement contracts must include peel strength and thermal aging tests to ensure that the seals are durable.
This reduces the risk of long-term liability for the battery pack manufacturer.
Material Solution
Primers and surface treatments on the aluminum foil are used to strengthen the bond. Modern cell manufacturers use chromate-free conversion coatings to improve the adhesion of the pouch cell laminate. Sourcing agreements should specify that the supplier must use these advanced treatment methods to guarantee seal reliability.
This ensures that the batteries can be used in demanding automotive or industrial applications.
