Solid-state electrolytes could make for denser, safer batteries

— 7:39 AM on August 24, 2015

Anybody who's ever used a cell phone, tablet, or laptop with a rechargeable battery wants more—more battery life and more usable charging cycles. Owners would also prefer that the batteries powering their devices not catch fire. MIT researchers working in conjunction with the Samsung Advanced Institute of Technology in Cambridge, Massachusetts say they've solved all three issues with this one weird trick a practical solid-state electrolyte. The very nitty-gritty details have been published in the peer-reviewed academic journal Nature Materials

MIT visiting professor of materials science and engineering Gerbrand Ceder says using a solid-state electrolyte, rather than the liquids that today's rechargeable batteries use, is a "game changer." According to Ceder, conventional wisdom held that solid materials cannot conduct ions fast enough to make an efficient battery, but the material the researchers discovered shatters that view.

The researchers homed in on a group of materials known as superionic lithium-ion conductors. As of today, these conductors are made from compounds of lithium, germanium, phosphorus, and sulfur, but the researchers believe that more compounds could eventually be found based on the methods they employed.

It seems that solid-state electrolytes would be more expensive to produce at first versus existing technologies, but the benefits seem to be worth the added cost. Ceder told the MIT News Office that "all of the fires you’ve seen, with Boeing, Tesla, and others, they are all electrolyte fires. The lithium itself is not flammable in the state it’s in in these batteries. [With a solid electrolyte] there’s no safety problem—you could throw it against the wall, drive a nail through it—there’s nothing there to burn."

Along with the safety improvements, Ceder says solid electrolytes won't degrade over time, which would make for batteries that could last "hundreds of thousands of cycles." He also notes that batteries made with the new material could function in environments where traditional electrolytes fail, like extremely cold temperatures. MIT further believes that solid-state batteries could result in power density improvements of 20% to 30%.

Feature image: Yan Wang, via MIT

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