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Sat12202014

Technology

Finding flaws on the manufacturing floor for better lithium-ion batteries

Finding flaws on the manufacturing floor for better lithium-ion batteries
This thermal image was recorded using a new tool developed at Purdue that detects flaws in lithium-ion batteries as they are being manufactured, a step toward reducing defects and inconsistencies in the thickness of electrodes that affect battery life and reliability. (Credit: Purdue University)

Researchers at Purdue University have developed a technique to check the electrodes of a lithium-ion battery for defects as early as the manufacturing stage.

Defects and inconsistencies in the thickness of lithium-ion batteries electrodes can affect battery life and reliability. A lithium ion-battery has two electrodes, an anode and a cathode. Lithium ions travel from one to another while the battery is being charged and discharged.

Most anodes and cathodes are copper on one side and coated with a black compound or “battery paint” to store lithium on the other. Battery paint is a mixture of carbon particulates that store lithium, chemical binders and carbon black.

Battery paint expands and contracts as lithium ions travel and this can cause the material to deteriorate and eventually damages the battery, affecting its lifespan. The quality of an electrode depends on the battery paint being applied with uniform composition and thickness.

“A key challenge is to be able to rapidly and accurately sense the quality of the battery paint,” said James Crauthers, Reilly Professor of Chemical Engineering and co-inventor of the new sensing technology.

The Purdue researchers use a flashbulb-like heat source and a thermal camera to read how heat travels through the electrodes. This takes less than a second and reveals differences in battery paint thickness and composition.

Through the thermal image produced by their technique, they found that battery paint is sometimes spread unevenly, producing a wavelike pattern of streaks that impacts battery performance.

"This technique represents a practical quality-control method for lithium-ion batteries," said Douglas Adams, Kenninger Professor of Mechanical Engineering and director of the Purdue Center for Systems Integrity. "The ultimate aim is to improve the reliability of these batteries."

The process is ideal for the manufacturing line as it presents a fast and accurate way to detect flawed electrodes prior to assembly into a working battery, allowing the manufacturer to fix them on the spot.

Purdue has already applied for a patent on the technique. – EcoSeed Staff



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