The end of exploding gadgets? Researchers reveal lithium-ion batteries with built in flame retardant

Batteries have a tendency to catch fire due to the flammable liquids inside them
But researchers have developed new batteries with built in fire extinguishers
They use a flame retardant to separate the flammable parts of the battery
When the battery reaches a temperature of 150°C, a fiber layer coated in a fire retardant melts, releasing the chemical and extinguishing the fire

Published: 19:39 EST, 16 January 2017 | Updated: 19:41 EST, 16 January 2017

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In recent months, horror stories of exploding gadgets have dominated the news, from Samsung's Galaxy 7 fiasco to unexplained explosions of other handsets.

Now, researchers have revealed a new type of battery with a built in fire retardant to stop them from exploding.

The researchers based at Stanford University designed the battery with a built in fire extinguisher to stop the highly flammable contents of the battery from catching fire.

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A cross-sectional view of the flame retardant fibers arranged together in a layer. The layer separates the negative and positive electrodes of the battery. If the temperature inside the battery reaches 150°C, the fiber layer coated in the fire retardant chemical melts, releasing the chemical and extinguishing the fire

WHY ARE BATTERIES PRONE TO BURSTING INTO FLAMES?

Lithium-ion batteries are found in everyday items including laptops, mobile phones, iPods and other electrical products.

They are very common because they are one of the most energetic rechargeable batteries available.

The batteries do have the ability to burst into flames, and while it is uncommon, when they ignite they can cause an extreme fire.

Lithium-ion batteries are very sensitive to high temperatures. Heat can cause the battery packs to degrade much faster than they normally would.

If the battery fails there is a chance the pack could burst into flames.

They can pose a danger and safety hazard since they contain, unlike other rechargeable batteries, a flammable electrolyte and are kept pressurized.

They used a flame retardant compound called Triphenyl Phosphate to separate the flammable components of the battery.

A typical lithium-ion battery consists of two electrodes (one negative and one positive) and a liquid or gel electrolyte that carries charged particles between them.

Puncturing, shorting or overcharging the battery generates heat.

If the temperature reaches about 300 degrees Fahrenheit (150 degrees Celsius), the electrolyte could catch fire and trigger an explosion.

But with this new technology, when the battery reaches a temperature of 150°C, a plastic fiber layer coated in the fire retardant chemical melts, releasing the chemical and extinguishing the fire.

The fibre separator keeps the retardant from coming into contact with the electrolyte unless the battery reaches a temperature of 150°C, or else it would reduce the battery's performance when it's working normally.

In tests, the researchers found that the retardant merged with the flammable electrolyte in the battery in just 0.4 seconds, and fires were avoided.

The researchers took videos of their attempts at burning fibers that were not coated in the retardant and other fibers that were coated in the retardant to see how well the chemical works at preventing fires.

While the new separator technology has been successfully tested in a coin cell battery, the researchers say that more testing needs to be done to see if the flame retardant still works when larger batteries are crushed or damaged in other ways.

Samsung infamously ran into problems with lithium ion batteries with their note 7 model.

The brand was plunged into a global scandal after Note 7 phones caught fire last year, prompting a worldwide recall.

Koh Dong-jin, Samsung's mobile president told reporters in Seoul: 'The flaw in the manufacturing process resulted in the negative electrodes and the positive electrodes coming together.'

It is unclear how Samsung failed to discover the battery problem before launching the Note 7.

Some customers reported fixed phones overheated, leading Samsung to take back replacements as well.

The first report of a Note 7 explosion surfaced on August 24th, 2016 in South Korea.

A week later, Samsung announced a global recall of 2.5 million Note 7 phones, citing faulty batteries.

A typical lithium-ion battery consists of two electrodes (one negative and one positive) and a liquid or gel electrolyte that carries charged particles between them. Puncturing, shorting or overcharging the battery generates heat. If the temperature reaches about 300 degrees Fahrenheit (150 degrees Celsius), the electrolyte could catch fire and trigger an explosion

On September 8th, the U.S. Federal Aviation Administration advised passengers to not turn on or charge Note 7 smartphones aboard aircraft or stow them in plane cargo.

On September 15th, the U.S. Consumer Product Safety Commission formally announced the recall of about 1 million Note 7 phones.

In October, A Southwest Airlines plane in the US was evacuated due to smoke from a Note 7 device on board.

Finally on October 11th, Samsung asked its customers to stop using all Note 7 smartphones and halted its production, sales and exchanges of the device globally.

GALAXY NOTE 7 FIASCO

Ms Shedletsky and colleagues took apart one of the phones and found it did not leave enough space for the battery to swell when it expanded during charging.

'When batteries are charged and discharged, chemical processes cause the lithium to migrate and the battery will mechanically swell,' the blog says.

'Any battery engineer will tell you that it's necessary to leave some percentage of ceiling above the battery, 10% is a rough rule-of-thumb, and over time the battery will expand into that space.

'Our two-month old unit had no ceiling: the battery and adhesive was 5.2 mm thick, resting in a 5.2 mm deep pocket.'

The researchers said this flaw could have been overlooked when Samsung engineers developed the phone.