Date: Feb 6, 2018
Like many humans, lithium-ion batteries typically don’t like the cold, which means they don’t perform well at freezing temperatures.
Now researchers in China may have solved this problem by developing a new lithium-ion battery system that can endure unprecedented temperatures even as low as minus-40 degrees Fahrenheit giving it potential for use as an EV battery that doesn’t succumb to cold weather.
A team from Fudan University in Shanghai has developed a cold-enduring hard-carbon anode and a lithium-rich cathode that integrates the important lithiation step in lithium-ion batteries in a way that hasn’t been done before.
Scientists long have known that so-called non-graphitizable, or “hard” carbon is a promising, low-cost material for cathodes, partially due to the fact that even at low temperatures, it demonstrates fast intercalation kinetics of lithium ions, according to the team, led by Yonggang Wang, a professor of physical chemistry at the university. However, carbon has posed a problem due to the prelithiation stage of the battery charge-and-discharge process, researchers said.
During charging/discharging of a battery cell, lithium ions migrate from the cathode through an electrolyte to the anode and vice versa. If the material used for the anode—often graphite–contains prestored lithium, the volume change by the incoming lithium ions is leveled out to ensure a longer cell life and a faster charge/discharge process. This is called prelithiation.
While prelithiated hard carbon has been proven a viable and strong material in lithium-ion capacitors, its prelithiation process–which involves a pure lithium electrode–is complicated and expensive, researchers said. This is why the explored alternative processes in their work.
