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Power-draining ‘flaw’ revealed in phone and laptop batteries

A new study from Canadian researchers has investigated why fully charged electronic devices such as iPhones can sometimes lose power when they’re not being used (Getty Images)
A new study from Canadian researchers has investigated why fully charged electronic devices such as iPhones can sometimes lose power when they’re not being used (Getty Images)

Have you ever wondered why your fully charged laptop or phone loses power even when they’re not being used?

Though the lithium-ion batteries inside our electronics deteriorate with age, there could be another culprit causing them to idly drain away.

In a new study, scientists claim the issue known as “self-discharge” is the result of a “manufacturing flaw” in widely used batteries.

The problem is caused by the strips of tape that hold the battery components together, according to researchers from Canada’s Dalhousie University.

Fortunately, that means it can be easily fixed, and the academics — who are already working with Tesla on a battery research partnership — claim they’ve been inundated with requests from electronics makers searching for a solution.


Rechargeable lithium-ion batteries are commonly used within phones and other electronics due to the large amount of energy they can hold within a small and light package. They are made up of an anode, cathode, separator, electrolyte, and two current collectors (positive and negative).

When plugged in, the  positive electrode gives up some of its lithium ions, which move through the electrolyte to the negative electrode. This allows the battery to take in and store energy. When the battery is discharging, the lithium-ions move back to the positive end, creating a flow of electrons to power the device.

During this process, the battery is running out without sending out an electrical current. This causes the power to drain on your phone or laptop when it is not in use.

As part of their tests, the researchers exposed lithium-ion battery cells to different temperatures, including environments as hot as 85°C. That’s 15°C higher than the heat required to fry an egg.

During one of these experiments, the electrolyte solution in the battery cell turned bright red — something the academics had never seen before.

After further investigation, they found that the thin strips of metal and insulation coiled inside the battery components were held together by tape. Those strips of tape were made of polyethylene terephthalate, or PET, a type of plastic that is used in everything from bottles to clothing.

They realised that when the tape decomposes, it creates a molecule that continuously shuttles back and forth between the positive and negative electrodes. The problem is that the molecule does this all the time in the background and doesn’t switch off, causing the self-discharge.

Since publishing and presenting their findings, the team claim they’ve been approached by some of the world’s largest computer hardware and electric vehicle manufacturers.

They even proposed a fix for the issue: use a different plastic compound that is a tad more expensive, but also more stable, reports CBC.

One option could be polypropylene, which is used in more durable plastics such as those used in outdoor furniture or reusable water bottles, as it doesn’t decompose like PET and doesn’t form unwanted molecules.