A chance discovery in a Canadian lab could help extend the life of laptops, phones and electric car batteries.
Common adhesive tape on batteries may be responsible for many devices losing some of their power when turned off or not in use, according to scientists at Dalhousie University in Halifax. This is a phenomenon known as self-discharge.
“In our lab, we do a lot of very complicated experiments to improve our batteries, but this time we discovered something very simple,” said Dalhousie University’s Department of Physics and Atmospheric Sciences. said Michael Metzger, an assistant professor at news release“Commercially available battery cells have tape that holds the electrodes, like Scotch tape, and this tape chemically breaks down to produce molecules that lead to self-discharge.”
The solution is also simple, says Metzger. A more durable and stable replacement for the polyethylene terephthalate (PET) plastic tape commonly used in batteries.
“This is a commercially significant discovery,” said Metzger. “It’s a small thing, but it definitely helps improve battery cells.”
Metzger and his team are trying to understand why lithium-ion battery cells in inactive devices tend to lose some of their power and self-discharge.
“Every manufacturer of lithium-ion batteries around the world wants self-discharge to be as small as possible,” Metzger told CTVNews.ca in a joint statement with graduate student Anu Adamson. “All batteries have a small percentage of self-discharge that slowly drains the battery. This is very inconvenient for users and a major headache for the industry.”
The electrodes that power the battery are separated by an electrolyte solution, usually in the form of lithium. After exposing multiple battery cells to different temperatures, the researchers were surprised to find that the electrolyte turned bright red instead of normally clear. This discovery was made by Adamson and two other students of his.
Chemical analysis of the red electrolyte solution showed that at higher temperatures, new molecules were created within the battery due to the decomposition of the common PET adhesive tape often used to hold the components together in the battery. It became clear. Strong and lightweight, PET is also frequently used in plastic packaging, beverage bottles, and clothing fibers.
Researchers have noticed that the red molecule, dimethyl terephthalate, functions as a redox shuttle. This means that electrons can be transported between the positive and negative electrodes of the battery, causing self-discharge and power drain even when the battery is not in use. Ideally, the round trip of electrons in the battery should only occur when the device is on.
“It’s pretty simple. It’s in every plastic bottle, and no one would have thought it would have such a big impact on the aging of lithium-ion batteries,” Metzger said in a news release. said in “This is something we didn’t expect because no one has seen these inactive components, these tapes, plastic foils inside the battery cells, but if you want to limit the side reactions inside the battery cells, , should really be taken into account.”
The findings are outlined in a pair of studies published in. January 20th When January 23rd Published in the peer-reviewed Journal of The Electrochemical Society. Researchers are currently testing alternatives to PET tape.
“Because the PET in the tape is responsible for creating the redox shuttle, it should be replaced with a more stable polymer that does not break down in the harsh chemical reactions of lithium-ion batteries,” Metzger and Adamson told CTVNews. . about. “So far, the results look very promising. We will soon publish a new research paper on improved polymers for lithium-ion battery tapes.”
According to the researchers, their work has attracted interest from “some of the world’s largest computer hardware companies and electric vehicle manufacturers” who are looking to reduce self-discharge and improve battery performance.
“We visited some of these companies and they are planning to implement more stable polymers in battery cells,” Metzger said.
Metzger said in a release: So I explained to him that it was causing this self-discharge and asked, “What are you using in your cells?” He said, ‘PET tape’.”