A chance discovery in a Canadian lab could help extend laptop and cell phone battery life.
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 a tape, such as Scotch tape, that holds the electrodes together, and this tape breaks down chemically to produce molecules that lead to self-discharge.”
According to Metzger, the solution is also simple. 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. It has long frustrated and confounded consumers and manufacturers.
The electrodes that power the battery are held in 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.
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. That is, it transports electrons 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 very 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. increase. “This is something we didn’t expect because no one has seen these inert components, these tapes, plastic foils inside the battery cells, but if you want to limit 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 It was published in the Journal of The Electrochemical Society. Metzger said the research has attracted attention from companies keen to improve battery performance.
“Self-discharge is a very important indicator for them,” Metzger said of the US company he visited. 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’.”