Lithium-ion batteries have been a significant fire risk, in part due to the flammable electrolytes typically used. Image adapted from: adreas160578

Lithium-ion batteries are known to be risky—but not for much longer

Fire-extinguishing batteries

The invention of lithium-ion batteries brought a significant advance to battery technology. They are now used in almost all high-powered mobile devices such as mobile phones and laptop computers. However, the advance has not been smooth sailing, with numerous well-documented occurrences of lithium batteries catching fire or even exploding.

Fortunately, research published this week in Nature Energy suggests that we may have a solution to the fire problem.

One of the key issues in conventional lithium-ion or sodium-ion batteries is that the electrolytes typically used are highly flammable and can cause catastrophic fires or explosions. To make these batteries safer, the options include:

limiting their size (reducing capacity)
including physical barriers (which adds to weight)
including complex circuitry to try and isolate the battery before a problem occurs (which doesn’t work if there’s a short circuit or physical damage to the battery)
changing the battery electrodes.

However, all of these options make the batteries less useable, and don’t necessarily protect against risks associated with physical damage to the battery. As such, scientists have focused on addressing the electrolyte directly.

In the study, the researchers introduced a new electrolyte comprised of a concentrated salt (NaN(SO₂F)₂ or LiN(SO₂F)₂) dissolved in a flame-retardant liquid (trimethyl phosphate). This electrolyte can perform as well as or better than other electrolytes, and won’t catch on fire!

This isn’t the first time chemists and engineers have tried to introduce flame-retardants into the electrolyte, but previous attempts have usually resulted in degradation of the battery electrodes or the electrolyte itself, effectively shortening battery life. This doesn’t seem to be the case with the new electrolyte, however, with tests showing cycling of over a year leading to negligible degradation of the battery.

And one of the best bits … the researchers report that their electrolyte has comparable or superior performance to conventional electrolytes, meaning that we wouldn’t have to accept a drop in performance or lifetime with this new technology. It just may pave the way for safer, lighter, higher energy-density batteries and large-scale power storage options.