Canadian team identifies alternative tape that prolongs life of most laptop, cellphone batteries

A team of Canadian researchers have identified a new way to prolong the battery life of most laptops and cellphones after discovering a power-drainage flaw last year.

The solution? A different kind of tape.

Typical laptop and phone batteries use tiny pieces of tape made of polyethylene terephthalate (PET), a synthetic resin, to hold its components together.

The team at Dalhousie University's battery lab in Halifax determined in November of last year that this type of plastic can dissolve due to a chemical reaction in the battery, causing its charge to deplete without sending out electrical current — a process called self-discharge.

This is why devices that are fully charged can slowly lose their charge even while they're turned off.

A metallic sheet from inside a cylindrical battery shows greenish tape strips that uses polyethylene terephthalate. (Brett Ruskin/CBC)

"Nobody, I think, thought that it could be the tape," Anu Adamson, a PhD student who helped lead the research, told CBC Radio's Mainstreet Halifax.

"Because to a degree, self-discharge is seen as something inevitable, really …  like we can't make totally perfect batteries. Most people thought that if there is a fix, then it can't be that simple, but it just turns out that it actually can."

Adamson said the team determined that using chemically stable polypropylene (PP) tape instead can increase battery life up to 10 per cent and decrease self-discharge by up to 70 per cent — a discovery that was published in the scientific journal Nature Materials last week.

She said the chemical bonds in polypropylene are a lot stronger, which make it more stable, while still being capable of holding the battery together.

Polypropylene is typically used to make more durable plastic items like outdoor furniture or reusable water bottles.

Adamson said the tape that is currently used in lithium-ion batteries is relatively cheap, but polypropylene tape costs about the same, so there's no reason to not make the switch.

She said battery researchers and manufacturers don't often think about these inactive components because they don't play a significant role in the battery's operation — but they're still important.

"This is really the first time we've seen that something that is generally regarded as very inactive in batteries, is essentially anything but," she said.

Jeff Dahn, a professor emeritus in the Dalhousie University's departments of physics, atmospheric science and chemistry, praised Adamson's discovery.

"This is really incredibly nice chemical detective work," said Dahn, who researches lithium-ion batteries.

"And it takes a very talented student to do this type of thing — to recognize all the connections between the various things that are going on in a lithium-ion battery and come up with this idea, is incredibly impressive."

Dahn, who wasn't involved in this research, said researchers have been puzzled as to why some lithium-ion batteries were self-discharging.

He said the tape dissolving has been a "very severe and an enormous problem" and switching to polypropylene will make a huge difference.

It makes sense, he said, as polypropylene is well known to be fully stable in both lithium-ion and sodium-ion batteries.

"It's something really simple that I think everyone should do, and I'm sure that most manufacturers will make the change," he said.

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