A new polymer-based electrolyte made Li-ion batteries non-flammable
Researchers from Stanford University developed a type of non-flammable electrolyte for lithium-ion batteries.
The new polymer-based Solvent-Anchored non-Flammable Electrolyte, abbreviated as SAFE, allows electronic devices to function at high temperatures without starting a fire.
Most of our electronic devices are charged by lithium-ion batteries.
However, they carry some risk of fire. This is because lithium-ion batteries have a heating issue.
If they get too hot, they can combust and can catch fire.
That’s partly because the electrolyte inside them, which is a substance that carries lithium ions between the two electrodes as the battery charges and discharges, is flammable.
“One of the biggest challenges in the battery industry is this safety issue, so there’s a lot of effort going into trying to make a battery electrolyte that is safe,” said Rachel Z Huang, a graduate student at Stanford University and first author of the new study.
An extra salty electrolyte
Conventional lithium-ion battery electrolytes are made of lithium salt dissolved in a liquid organic solvent, such as ether or carbonate. While this solvent improves battery performance by helping to move lithium ions around, it’s also a potential firestarter.
At temperatures above 140 degrees Fahrenheit (60 degrees Celsius), the solvent used in conventional electrolytes starts to evaporate, transforming from liquid to gas, and causing the battery to swell up like a balloon. The gas then catches fire, causing the entire battery to explode.
Researchers have been trying to develop non-flammable electrolytes for decades now. This includes polymer electrolytes, which use a polymer matrix instead of the classic salt-solvent solution to move ions around.
However, these alternative electrolytes underperform in comparison to conventional ones.
The team led by Yi Cui, a professor at SLAC National Accelerator Laboratory and Stanford, wanted to produce a polymer-based electrolyte that could offer both safety and performance.
And the trick that made the electrolyte safe and efficient was adding as much of a particular lithium salt (LiFSI) as possible to a polymer-based electrolyte, bumping the mix from less than half of the electrolyte’s weight to 63 percent.
The additional salt anchors the molecules of the electrolyte, preventing them from evaporating in high temperatures and thus stopping them from catching fire. In temperature tests, the lithium-ion battery continued functioning at temperatures as high as 212 degrees Fahrenheit (100 degrees Celsius).
“I just wanted to see how much I could add and test the limit,” Huang said. Usually, less than 50 percent of a polymer-based electrolyte’s weight is salt. Huang bumped that number to 63 percent, creating one of the saltiest polymer-based electrolytes ever.
Gooey flameproof batteries
One key feature of the team’s new electrolyte is that it has a gooey form similar to conventional electrolytes, which means it can be integrated with existing battery parts, unlike other experimental, non-flammable electrolytes.
The research team put forward that this could be used in electric cars. If the lithium-ion batteries in EVs were packed with this new electrolyte, then the risk of combustion would be much lower.
It could also lead to more efficiency in batteries, with less space dedicated to cooling systems and more dedicated to battery capacity.
“This very exciting new battery electrolyte is compatible with the existing lithium ion-battery cell technology and would make big impacts on consumer electronics and electrical transportation,” said Professor Yi Cui.
The study was published in the journal Matter.
See more here interestingengineering.com
Header image: Jian-Chiang Lai
Bold emphasis added
Please Donate Below To Support Our Ongoing Work To Defend The Scientific Method
PRINCIPIA SCIENTIFIC INTERNATIONAL, legally registered in the UK as a company 
incorporated for charitable purposes. Head Office: 27 Old Gloucester Street, London WC1N 3AX.
Trackback from your site.
Carmel
| #
Is the performance of the new electrolyte battery equal to a comparable conventional lithium ion battery?
So the new electrolyte battery continued to function up to 100°C instead of 60°C before becoming unsafe. And then what?
Lithium ion batteries in the fire prevention and safety industry are classed as a high hazard risk of fire and explosion with the potential to release toxic hydrogen fluoride gases.
So do these new electrolyte batteries carry an even greater fire and explosion risk than comparable conventional lithium ion batteries or less risk or the same risk?
Lithium ion/electrolyte batteries may also become hazardous when subjected to low temperatures, high humidity and exposure to water especially salt water, when exposed to unstable electricity/grid frequencies, when at zero charge, if hit by lightening and if damaged in production, transportation or installation and disposal.
There is always a percentage of battery cells that are damaged in the manufacturing process. The lower the quality of production the higher the percentage of damaged battery cells.
All it takes is for one damaged battery cell in a pack to auto-combust to trigger a thermal runaway in adjoining battery cells leading to a high risk of fire and explosion. When this happens temperatures can rapidly soar to around 1000°C. In this instance it matters little whether the electrolyte in a battery can withstand a temperature of 60°C or 100°C.
Reply
David O'Neill
| #
How much weight would this add to a typical EV battery and is the rate of charge/discharge reduced?
What temperatures could typically be reached during fast charge/discharge of a grid scale system?
Reply
T. C. Clark
| #
What about all the “new” batteries? The sodium ion?….the solid state?…..the glass battery?….the Elon Musk battery?…..the plastic one?…..the ad infinitum one?
Reply
Dave
| #
The denser these batteries become the more volatile they will be, it’s call physics.
Reply
Howdy
| #
Sounds like a kludge to me. Thermal runaway will still ignite the Lithium, and if the casing holding the cells is not up to snuff, same result. I don’t see it helping for a phone in your pocket for example. Nor do I see it of any benefit in vehicles, where wiring and electronics won’t stand it.
Reply