New materials in batteries help to prevent fire

Researchers at Oak Ridge National Laboratory - ORNL (Tennessee, USA) developed a solid electrolyte to replace flammable substances used in lithium-ion batteries.

Why is this problem important?

Batteries with safer, cheaper features are always needed to help make electric cars easier to compete with other cars.

The electrolyte developed at Oak Ridge National Laboratory could allow lithium batteries to store five to 10 times more energy and safer than batteries that recently burned the Boeing 787 Dreamliner.

While the cause of the fire on Boeing aircraft has not been determined, Boeing may reduce the risk of fire by choosing a safer chemical electrode. But there will be fewer options for electrolytic materials that only allow current to flow through a battery. Lithium-ion batteries, even those that use relatively safe electrodes, still use flammable liquid electrolytes.

This microscope image shows a powder material
Nano structure (right) improves battery conductivity.

Solid electrolytes will be safer, but it is difficult to make them have enough conductivity to be used in batteries. However, ORNL researchers, in a new study published recently in the Journal of the American Chemical Society, have developed a fairly easy way to create the nanostructures of solid electrolytes. Nanostructures improve the conductivity of materials by 1,000 times, enough to make it useful in making lithium-ion batteries. The researchers also showed that the new material is compatible with high-energy electrodes.

Solid electrolytes are not as highly conductive as liquid electrolytes, but researchers say they can overcome this in many ways, including a solution that makes the electrolyte very thin. Although it has been done this way, the battery still cannot charge quickly or energize quickly with a liquid electrolyte, but it has met the requirements in many applications, such as in electric cars, Where large numbers of battery rods allow easy full supply when a sudden increase in electrical current is required.

Solid electrolytes not only make the battery safer, it can also allow the use of higher energy electrode materials. As a result, although the power supply rate may be less than the current lithium-ion battery, the total energy they can store will be much higher. One only needs to use a much smaller battery - thereby saving space and weight on the aircraft and significantly reducing the cost of electric cars.

Solid electrolytes can be especially suitable for lithium sulfur batteries - this is a type of battery that can store a lot of energy but has a safety and charge problem many times over a car's lifetime. steam. Lithium-metal electrodes can cause the battery to short-circuit and burn. Solid electrolyte helps stabilize lithium metal and serves as a barrier to short circuit. Sulfur electrodes in these batteries are also degraded when used with liquid electrolytes - some of the sulfur can be dissolved in liquid and lost. Solid electrolyte prevents that.

Work is still at an early stage. Until now, researchers have only been able to test small, half-inch-sized test batteries, and the results of demonstrating compatibility with lithium-sulfur batteries have yet to be announced.