A novel way to put flame retardant in a lithium ion battery

Source: phys.org

A team of researchers at Stanford University has found a novel way to introduce flame retardant into a lithium ion battery to prevent fires from occurring. In their paper published in the journal Science Advances, the team describes their technique and their results when testing it.

Reports of phones and hoverboards catching fire due to short circuits in batteries have caused alarm in the personal electronics industry—both by users and those that make the devices. Unfortunately, up until now, engineers have not been able to solve the problem completely. Most such efforts involve re-engineering devices to prevent short-circuiting and thus overheating, or attempting to put flame retardant directly in the batteries. Neither approach has proven to be entirely satisfactory. Rea-engineering does not always solve the problem and the addition of flame retardant greatly reduces battery efficiency. In this new effort, the researchers describe an approach that thus far appears to offer some help—it does not stop overheating from occurring, but it is able to prevent fire.

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The new approach involves encapsulating a common flame retardant called triphenyl phosphate in an extremely tiny sheath made of plastic fibers and then inserting several of them into the electrolyte that sits between the anode and cathode. The sheath keeps the retardant from actually coming into contact with the electrolyte material, which is flammable and the source of most battery fires. But the plastic fibers in the sheath have a melting point of 160° Celsius—if that temperature is reached, the plastic melts and the retardant is released into the electrolyte quashing a potential fire.

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Pinfa Newsletter N° 74

Pinfa Newsletter N° 74 is now available, Download: Click here

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New approaches to the development of fire-safe materials

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Authors: Alexander B. Morgan, Jeffrey W. Gilman, Marc Nyden, and Catheryn L. Jackson.

Abstract

Thermoplastic polyetherimide-clay nanocomposites were synthesized from 1,3-phenylenediamine and bisphenol A dianhydride using an in situ approach. Two types of organically treated clays were utilized to synthesize these nanocomposites. The two organically treated clays were montmorillonite clays treated with the ammonium salts of n-dodecylamine or 12-amino-1-dodecanoic acid. The dispersion of the clay in the polyetherimide was analyzed by wide-angle X-ray scattering and transmission electron microscopy. The results showed that the clay treated with the ammonium salt of 12-amino-1-dodecanoic acid gave a well-dispersed intercalated nanocomposite while the clay treated with the ammonium salt of n-dodecylamine gave a well-dispersed immiscible blend. Read more: click here

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