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It’s not unheard of for Li-ion batteries to catch fire or explode when damaged or poorly designed, just look at Samsung’s recent debacle with the Galaxy Note 7, and you can see why. The problem with most catastrophic failures in these types of batteries is heat, or rather a buildup of heat resulting from damage or short circuit, which causes a chain reaction that can’t be cooled sufficiently to stop it.
As the battery’s electrodes charge and discharge when ions move from one to the other, organic electrolytic chemicals help make it easy for those ions to travel back and forth. Unfortunately, those electrolytes have a tendency to become volatile when a crap-ton of heat is introduced, causing it, in some cases, to boil and catch fire.
Sounds scary doesn’t it, as failure/fire/explosions often happen when we least expect it, even more so when you consider Li-ion batteries are everywhere- mobile devices, jumbo jets, your favorite Tesla Model S, solar arrays and much more. Suffice it to say, we rely on these batteries to live our daily lives and would prefer them to be as fireproof as possible.
Researchers from the University of Maryland may have a solution to the pyro problem by replacing the organic-based electrolyte with a water-based version. Fireproof water-based electrolytes are nothing new, but they have an issue at producing enough volts to become relevant, meaning they’re not very powerful. UMD’s version however, is capable of producing 4-volts or enough juice as some organic-based electrolytes.
Water-based electrolytes aren’t without its problems either- Chunsheng Wang (co-author of a recent paper outlining the development of their new battery) and his team worked with the US Army to develop a 3-volt water-based electrolyte battery, and while it was successful, it degraded one of the electrodes, resulting in reduced energy storage capacity. Wang and his team overcame this issue for 4.0 by using a solid coating to protect the electrodes from degrading.
Li-ion batteries that feature organic-based electrolytes have some of the chemical decompose, creating a protective layer on the surface of the electrode- this is known as a SEI or Solid Electrolyte Interphase, which doesn’t happen with water-based electrolytes. The solution to that problem is literally in the solution as Wang and his team dosed that water with enough salt to kill slugs, thereby creating a SEI to protect the electrodes and thus- allowing it to hold more energy.
Alas, this new battery has one last issue to overcome, as it only lasts for about 70-cycles of recharging, whereas most commercial manufacturers require batteries that can last for 500-cycles or more. This is the issue Wang and his team are currently working to overcome, considering they solved the combustion issue, I have no doubt Wand will be successful in his endeavor.
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