Published on May 17th, 2013 | by James Ayre2
Improved Quality Control During Lithium-Ion Battery Production Thanks To New System
A new tool has been created by researchers at Purdue University that is able to detect flaws in lithium-ion batteries while they are still being manufactured, potentially greatly improving the quality and reliability of the batteries and also cutting down on waste/inefficiency.
Specifically, the new tool is able to flag defects and inconsistencies in the thickness of electrodes that can limit the battery’s life and reliability. As a result of the inconsistencies being spotted right there during manufacturing, they can be fixed then and there, potentially saving a great deal of time and material.
The press release explains:
The electrodes, called anodes and cathodes, are the building blocks of powerful battery arrays like those used in electric and hybrid vehicles. They are copper on one side and coated with a black compound to store lithium on the other. Lithium ions travel from the anode to the cathode while the battery is being charged and in the reverse direction when discharging energy.
The material expands as lithium ions travel into it, and this expansion and contraction causes mechanical stresses that can eventually damage a battery and reduce its lifetime.
The coating is a complex mixture of carbon, particulates that store lithium, chemical binders and carbon black. The quality of the electrodes depends on this “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 Caruthers, Reilly Professor of Chemical Engineering and co-inventor of the new sensing technology.
Which is what the newly developed tool does. The new system utilizes a flashbulb-like heat source and a thermal camera in order to analyze how the heat moves through the electrodes. The process is fast, taking less than a second, and shows in detail the local differences in thickness and composition.
“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 technique is able to spot when the viscous compound is spread unevenly, to spot differences in the ratio of carbon black to the polymer binder and a variety of other flaws — such as scratches, air bubbles, contaminants, inconsistencies in thickness, etc.
This technique is ideal for a manufacturing line because of its speed and accuracy, allowing the quick detection of flaws prior to further assembly.
“For example, if I see a difference in temperature of more than 1 degree, I can flag that electrode right on the manufacturing floor,” Adams said. “The real benefit, we think, is not just finding flaws but also being able to fix them on the spot.”