E-Mail Nanoengineers at the University of California San Diego have discovered new fundamental insights for developing lithium metal batteries that perform well at ultra-low temperatures; mainly, that the weaker the electrolyte holds on to lithium ions, the better. By using such a weakly binding electrolyte, the researchers developed a lithium metal battery that can be repeatedly recharged at temperatures as low as -60 degrees Celsius--a first in the field. Researchers report their work in a paper published Feb. 25 in Nature Energy. In tests, the proof-of-concept battery retained 84% and 76% of its capacity over 50 cycles at -40 and -60 degrees Celsius, respectively. Such performance is unprecedented, researchers said.