Fire extinguisher built into battery

Fire extinguisher battery

There is never a great deal of time pass between battery safety issues hitting the mobile phone news. We recently had Samsung withdraw the Samsung Galaxy Note 7 from sale, due to battery fires, and before this, similar claims have been made against the Apple iPhone.

Lithium-ion batteries, which are used in smartphones, are filled with highly flammable liquid organic electrolytes. Fire, or battery explosions, tend to happen when a battery is charged too quickly or if there happens to be a small manufacturing fault that could lead to a short circuit.

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The problem is that energy densities in batteries are increasing but safety technology has not moved along at the same rate. If this trend continues, then it will hinder the practical applications of the next generation of batteries.

How the battery fire extinguisher works

The battery fire extinguisher comprises of a smart non-woven electrospun separator, with flame retardant properties, that are thermally triggered. This basically means that the flame retardant sits inside a protective polymer shell, which itself sits within the liquid electrolytes.
 
Should a thermal runaway event occur, then the protective polymer shell will melt and the retardant will suppress any combustion, of the highly flammable electrolytes. 

Thermal triggering

A polymer shell was created so that it would not melt during normal battery operation. However the polymer shell would melt at relatively low temperatures, of less than 160°C, which is the temperature that is reached just prior to the moment of combustion.

What is crucial with this system is that there is no payoff in battery performance. The flame retardant is cheap and if triggered it will only release low levels of environmental pollution.

In tests, battery fires were extinguished within 0.4 seconds.

Bendable battery developed

Moving a proven model such as this, from the lab to production, takes time. However, battery fires in mobile phones is a burning issue, meaning that there is a demand for such a solution.

References

The thermal-triggered flame-retardant extinguisher for lithium-ion batteries is detailed in a peer-reviewed paper, from the Stanford University research team, and published in the Science Advances journal

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Written by: Michael Brown

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