Organic battery tech could work better than a woolly hat in the cold

Parky Prius? Frosty fondleslab? Help may soon be at hand

Brits may soon have one less thing to whinge about during cold snaps – thanks to research into the performance of Li-ion batteries in freezing temperatures.

Once the mercury drops below 0°C, commonly used electrolytes start to freeze and ionic conductivity becomes problematic.

In other words, a battery that seems to have plenty of charge will drain faster or suddenly go dead when things get a bit chilly.

Wrapping a phone up in a blanket goes some way to alleviating the problem. The Samsung approach to keeping batteries toasty is not advised.

Scientists Yongyao Xia and Yonggang Wang of Fudan University in Shanghai, China, have published the results of their research into alternatives to the electrolyte technology found in most commercial Li-ion batteries.

A previous 2017 study showed that using liquified gas as an electrolyte helped a battery function at 60 per cent efficiency down to -60°C, but keeping the gas as a liquid proved a challenge.

Xia and Wang looked for an alternative, and settled on the solvent ethyl acetate as an electrolyte, which has a freezing point of -84°C. The boffins also used organic compounds for electrodes with impressively unpronounceable names – a polytriphenylamine cathode and a naphthalenetetracarboxylic dianhydride-derived polyimide anode.

The resulting battery was shown to retain 70 per cent capacity at -70°C compared to a positively balmy 25°C and nearly 100 per cent capacity at -40°C. After 500 cycles, the capacity retention was a promising 83 per cent.

It isn't just Brits getting grumpy with smartphones that may benefit from the research. Satellite manufacturers have long struggled with issues of extreme cold wreaking havoc on spacecraft, requiring energy-sapping heaters to keep things working, and electric vehicle makers have difficulties getting their kit to work in colder regions.

Although the technology should not present manufacturers with too many problems, researchers still need to work on the energy density on the battery before it makes the jump from lab to production line. ®

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