Chinese scientists may now have solved the two weaknesses of lithium batteries (extreme cold and durability), with a new electrolyte for lithium batteries that withstands cold temperatures and could double the range of electric vehicles.
A team of researchers from Nankai University in Tianjin and the Shanghai Institute of Space Power Sources (SISP) has developed a hydrofluorocarbon-based electrolyte that significantly improves the performance of lithium batteries.
The invention was recently disclosed in a study published in , by this team of Chinese engineers.
As noted by , the new electrolyte more than doubles the energy density of existing batteries at room temperature, meaning that batteries of the same size can last twice as long.
O new electrolyte remains stable in extreme coldallowing the batteries operate smoothly in temperatures as low as -70°C.
As explained by , this type of battery uses electrolytes – a chemical medium that allows ions to flow between the positive and negative electrodes, converting the stored chemical energy into electrical current. In lithium batteries, electrolytes are typically ccompounds based on nitrogen and oxygenmainly due to its effectiveness in dissolving lithium salts.
However, these electrolytes are sensitive to operating temperatures. Low temperatures increase viscosity and slow ion mobility, reducing charge transfer efficiency. When this happens, the battery provides less power, takes longer to charge and even loses usable capacity, providing less autonomy than its stored energy would suggest.
In the new study, the researchers show how their solution, electrolytes synthesized based on hydrofluorocarbons (hydrogen, fluorine and carbon), eliminates this problem in lithium batteries. The cold-resistant electrolyte offers greater stability and lower viscosity at low temperatures, allowing batteries to continue functioning in extreme subzero temperatures.
Another notable feature of the electrolyte is its energy density – the amount of cargo it can store per unit of weight. In the study, the team created lithium metal pouch cells that achieved an energy density of 317 watt-hours per pound (Wh/lb) at room temperature. The cells still maintained a density of 181 Wh/lb at -46 ºC.
By comparison, conventional lithium batteries, like those found in Tesla electric vehicles, have an energy density of 73-136 Wh/lb at room temperature. This value is reduced to less than half when temperatures drop to just -20 ºC.
That is, the researchers’ electrolyte could triple autonomy of some electric vehicles with the same battery size.
“For the same lithium battery mass, the energy storage capacity at room temperature increases two to three times,” said one of the study’s authors. Li YongSISP researcher, cited by New Atlas.
