Meaning
Material failure resulting from parallel forces that cause one part of a component to slide past another. In battery technology, shear rupture often affects the separator or the thin metal foils used as current collectors. This type of failure can lead to an immediate loss of function or a hazardous internal short circuit.
Mechanical Load
External impacts or internal expansion during cycling create the forces that lead to failure. When the shearing stress exceeds the yield strength of the polymer or metal, shear rupture occurs. The integrity of the separator is the most vulnerable point, as it is the only barrier preventing contact between the anode and cathode.
Tear Propagation
Damage often begins at a point of stress concentration and spreads through the material. Once shear rupture has initiated, the structural stability of the cell is compromised. This can happen during the manufacturing process if the winding tension is not correctly controlled.
Safety Consequence
Electrical contact between the positive and negative electrodes causes a rapid release of stored energy. Shear rupture in the separator allows for this contact, leading to localized heating and potential thermal runaway. High-strength materials and ceramic coatings are employed to increase the resistance to this failure mode.
