A team of researchers at the U.S. Department of Energy's (DOE) Argonne and Lawrence Berkeley laboratories have developed a new material designed to overcome an important problem electrical vehicle batteries experience: the impact of cold weather on battery performance. The team’s new material is described in a recent article published in Advanced Energy Materials.
The push towards electrical vehicles is increasing. Electrical vehicle sales jumped from .2% to 4.6% in just a decade, between 2011 and 2021. Coupled with new tax incentives, electrical vehicles are becoming more popular and financially accessible among consumers, especially as a way to help reduce carbon emissions.
A constant problem electrical vehicles face, however, has to do with how traditional batteries tend to function in colder temperatures and climates. Typical lithium-ion batteries work by transferring charged particles (ions) to the battery’s electrodes. These batteries use a liquid substance called an electrolyte to facilitate this transfer. As a liquid, however, battery electrolytes are prone to freezing in cold environments, limiting their usability and raising concerns among consumers about whether to purchase an electric vehicle. The problem has to do with how tightly bonded lithium ions are in the electrolyte material, and they require more energy to be released in these colder temperatures.
The new electrolyte material developed by researchers contains fluorine, which could improve the functioning of electric vehicle batteries in colder temperatures. What makes this new material promising is the low energy threshold need to evacuate lithium ions from electrolyte materials, even in colder temperatures. In initial tests, the team found that the fluorine-based electrolyte material was able to maintain a charge even in temperatures approaching zero degrees Fahrenheit. And despite that cold temperature, the batteries seemed to perform just as well as traditional batteries at room temperature. The team’s findings also highlight a new method for looking at electrolyte fluids at an atomic level to best determine ways to design new, more efficient, materials for electric vehicle batteries.
Interestingly, the new electrolyte material also has an unexpected benefit: because of its low freezing level, it is also safer than traditional batteries because it won’t catch on fire.