Electric vehicles currently use lithium-ion batteries, which have the highest energy density and a relatively long lifespan. However, most Li-ion battery cells can be dangerous when they overheat, requiring complex thermal management systems. Because they use highly flammable electrolytes, they can catch fire if the temperature is not controlled.
This phenomenon is known as thermal runaway, although from the outside, it appears like an explosion or a rocket engine firing. Since an electric vehicle battery is composed of thousands of individual cells, this process can affect neighboring cells unless it is stopped.
Scientists at Clemson University in the USA have developed a self-extinguishing electrolyte that could make battery fires a thing of the past. (Photo: Wikimedia Commons).
Worse still, burning cells generate their own oxygen, making it extremely difficult to extinguish the flames. The reaction continues at sufficiently high temperatures or as the electrolyte depletes. This is why firefighters dealing with electric vehicle battery fires focus on cooling the battery pack.
Researchers at Clemson University believe that inventing a non-flammable electrolyte is the simplest way to prevent battery fires. Instead of conventional electrolytes, which typically consist of lithium salts and organic solvents, they have developed an electrolyte based on materials found in commercial fire extinguishers.
This revolutionary electrolyte operates over a wide temperature range from approximately -100 to 175 degrees Fahrenheit (-75 to 80 degrees Celsius). During puncture testing, batteries produced in the laboratory with this fire-resistant electrolyte effectively extinguished internal fires.
Furthermore, the electrolyte is compatible with other chemistries besides Li-ion, including potassium ions, sodium ions, aluminum ions, and zinc ions.
Although non-flammable electrolytes are not new, most contain fluorine and phosphorus, are expensive, and can be harmful to the environment. Instead of using them, the research team focused on modifying commercially available coolants that are already widely used in fire extinguishers. The goal was to make them function as the electrolyte for batteries.
The affordable electrolyte produced by 3M, named Novec 7300, has low toxicity, is non-flammable, and does not contribute to global warming. The research team combined this liquid with other chemicals to enhance its stability. The result is an electrolyte that allows batteries to charge and discharge for an entire year without significant loss of capacity.
The most impressive aspect is that this electrolyte has similar physical properties to the electrolytes currently in use. This makes it easy to implement on existing battery production lines. Researchers are confident that companies will soon be able to manufacture non-flammable batteries using their existing lithium-ion battery infrastructure.
