"Mars rovers have a low temperature specification that most existing batteries cannot meet. Our new battery technology can meet these specs without adding expensive and heavy heating elements," said researcher Cyrus Rustomji. "The low viscosity leads to high ion mobility, which means high conductivity for the battery or capacitor, even in the extreme cold," he said.
The thermal shutdown is also important. "This is a natural shutdown mechanism that prevents the battery from overheating," said Rustomji. "As soon as the battery gets too hot, it shuts down. But as it cools back down, it starts working again. That's uncommon in conventional batteries."
This also helps with safety, for example in a car accident when the battery is crushed and shorted, the electrolyte gas may vent away from the cell and so prevent the thermal runaway that has caused fires in electric vehicles.
Using a low viscosity electrolyte needed changes to the electrodes and a fluorinated electrolyte additive to protect the lithium metal electrode from dendrites. The design shows a highly uniform and dendrite free surface allowing for a high Coulombic efficiency of over 97% and improved battery conductivity for both lithium metal and classical cathode materials.
The team is commercialising the technology through a startup called South 8 Technologies Moving forward, researchers aim to improve the energy density and cyclability of both batteries and electrochemical capacitors and to run at even lower temperatures -- down to -100 °C for new technology to power spacecraft sent to explore the outer planets such as Jupiter and Saturn.