New fireproof lithium battery -Lithium - Ion Battery Equipment

The United States develops a new type of fireproof lithium battery -Lithium - Ion Battery Equipment

At the 256th National Conference and Exposition (ACS) organized by the American Chemical Society (ACS) on August 22, researchers at Oak Ridge National Laboratory and the University of Rochester exhibited a new type of fire-resistant lithium battery, Its electrolyte can spontaneously change from liquid to solid when struck, preventing lithium batteries from catching fire when they rupture.

Lithium batteries are generally composed of positive and negative electrodes and an electrolyte. Once a lithium battery placed in an electric vehicle is subjected to a violent impact, the thin layer of plastic used to separate the positive and negative electrodes is easily broken, and the heat released by the chemical reaction after the battery is short-circuited will cause the battery. The temperature rises, and it is easy to cause accidents such as fire. Over the years, researchers have taken a variety of measures to reduce the risk of lithium batteries catching fire, including using non-flammable solids and adding specific substances to the electrolyte.(Lithium - Ion Battery Equipment)

At present, lithium batteries with solid electrolytes usually use plastic or ceramic materials, but due to the poor fluidity of solid electrolytes, their charge and discharge efficiency is lower, and some companies are also trying to use semi-solid electrolytes or glass-like electrolytes. Battery.

In this study, Gabriel Veith, the leader of the experiment, and his colleagues produced an electrolyte that can undergo liquid-solid transition. During normal use, the electrolyte can be charged and discharged in the form of a liquid, and has good electrical conductivity. When under pressure, such as when the battery is crushed or penetrated, the electrolyte becomes solid, preventing a large amount of heat release caused by the mixing of positive and negative chemicals, thereby achieving the purpose of preventing fire.

The ability to change the electrolyte from a liquid to a solid, Gabriel Veith says, was inspired by cornstarch suspended in water. When people put cornstarch in water and stir it, it's easy at first, but it gets thicker and thicker, and the cornstarch granules stick together and gradually become a solid that's hard to stir. Fluids with this characteristic are called shear thickening fluids. The researchers added 200-nanometer-sized silica particles to a liquid electrolyte as a diluting solvent for lithium ions. When impacted, these spherical particles of silica "stick" together like cornstarch granules, becoming an impenetrable solid material.

"The particle size of the silica added needs to be consistent and precise," said Gabriel Veith, "but the purpose of silica is not only to form a solid, but also to absorb the heat given off by the battery, further reducing the possibility of a lithium battery catching fire."

The use of shear thickening fluids as electrolytes for lithium batteries is not a first for the lab. It is understood that the addition of irregularly shaped or rod-shaped silica particles to the electrolyte has previously been reported by research groups, but the researchers believe that the spherical silica particles used in this study are easier to prepare and less Regularly shaped particles have faster strain capacity.

In addition, this achievement also provides new ideas for the production process of lithium batteries. In the manufacturing process of traditional lithium batteries, the electrolyte is usually injected into the battery casing in the last step of the production process, and then the battery is sealed. If a shear-thickening fluid is used as the electrolyte, Gabriel Veith says, it will solidify before injection. The researchers solved this problem by using a new process in which silica nanoparticles are placed in the stationary part of the battery first, and then a liquid electrolyte is added.

It is reported that the research team plans to further improve the system, trying to make the part of the battery that is damaged after the collision remain stable, and the rest can continue to work. The team's initial goal was for drone batteries, but they eventually hope to enter the automotive market.



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