Meaning
Electrochemical analysis determines the presence of trace water in liquid or solid samples down to the microgram level. The method known as karl fischer coulometry utilizes an electrolytically generated iodine solution to react quantitatively with water in the test cell. In battery manufacturing, this technique is the industry standard for measuring moisture in electrolytes and electrode materials.
Keeping moisture levels below fifty parts per million is essential to prevent the formation of hydrofluoric acid.
Quality Control
Production lines for lithium-ion cells require continuous monitoring of moisture to ensure cell safety and longevity. Laboratory technicians use karl fischer coulometry to test incoming solvent batches before they are introduced to the mixing line. If the moisture content exceeds the specified limit, the batch is rejected or sent for further drying.
This rigorous testing prevents the degradation of active battery materials.
Testing Method
The analytical procedure involves injecting a precise volume of sample into a sealed titration cell filled with anode and cathode solutions. Electric current generates the exact amount of iodine needed to consume the water present. The system calculates the water content from the total electrical charge consumed during the titration.
This precise calculation provides reliable results for high-purity chemicals.
Manufacturing Standard
Battery manufacturers include trace moisture limits in their procurement contracts. Adhering to karl fischer coulometry as the reference testing method ensures that both suppliers and producers use the same evaluation criteria.
