Lithium battery performance at freezing temperatures was something of a side show a decade ago. However, that reality is changing with more extreme weather, and space exploration in sub-zero conditions. Scientists at Beijing Jiaotong University in China discovered a practical way to improve lithium battery sub-zero performance.
Lumpy Anodes Improve Lithium Sub-Zero Performance
The Chinese scientists set themselves the target of improving sluggish lithium battery performance at low temperature. That’s because they currently take days to fully recharge below freezing, and store far less energy according to New Scientist. And moreover this can also reduce an electric vehicle’s driving range by up to 30%.
The team decided to experiment with the shape of a lithium-ion battery anode to see if this would make a difference. Now anodes play a vital role during battery charging and recharging, but are traditionally flat. This may be for manufacturing convenience. However, the Chinese scientists chose to break ranks and design a curved and bumpy one instead.
An Irregular Anode Performed Far Better Below Freezing
New Scientist explains conventional lithium-ion batteries only hold around 3% of their energy at -20° C (-4° F). Whereas, the alternative design at Beijing Jiaotong University in China retained around 86% of its energy at low temperatures. Moreover, the modified anodes lasted longer than standard lithium-ion batteries between -20°C and -25°C (-4° to -13° F).
The Science Behind This Remarkable Step Change
As we discharge and recharge a battery, active particles flow from and to the anode. New Scientist confirms most particles in regular lithium batteries “don’t have enough energy to make the trip near freezing”. And this means the battery is unable to deliver.
But “making the anode bumpy and rounded puts charged particles closer to each other” they explain. And this in turn “lowers the overall amount of energy they need to move”. The scientists successfully modified small, coin-shaped batteries, and are now developing larger ones.
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