Meaning
Physical measurement metrics quantify the volume of a fluid that passes through a leak path per unit of time under specified conditions. To evaluate cell seals, the volumetric leak rate measures the amount of gas or liquid that escapes from a lithium-ion cell, typically in cubic centimeters per second. This metric provides a direct and standardized way to compare the sealing quality of different battery cells.
Measurement Standard
The measurement is typically performed by placing the cell in a test chamber and measuring the change in pressure or volume over time. Alternatively, tracer gas methods can be used to measure the rate of gas escape with high sensitivity. This metric is a key indicator of the physical integrity of the cell housing and seals.
Supplier Evaluation
Sourcing teams use this metric to define the quality requirements for incoming cell shipments. A cell with a high leak rate will eventually lose electrolyte, leading to premature capacity loss and potential safety issues. Defining clear, measurable leak limits in supply contracts helps to ensure that only high-quality cells are accepted.
Limit Constraint
The measured leak rate can vary depending on the temperature and pressure differences across the leak path during the test. For this reason, the test conditions must be carefully specified. In addition, the test must be performed before the cell is filled with electrolyte.
