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Improving Safety of Lithium Ion Batteries

A team of Washington State University (WSU), Pullman, researchers has developed a gummy battery material that, they say, could dramatically improve the safety of lithium ion batteries.

High-performance lithium batteries have become ubiquitous these days because they can store a large amount of energy compared to other batteries. However, the biggest potential risk of all commercially available rechargeable lithium batteries comes from the battery’s electrolyte, which allow for the movement of ions between the anode and the cathode to create electricity. Liquid acid solutions can leak and create a fire or burn hazards. While commercial battery makers can add temperature sensors or flame retardant additives, they can’t solve the safety problem fundamentally, say the researchers.

The WSU group has developed a gum-like lithium battery electrolyte, which works as well as liquid electrolytes at conducting electricity but which doesn’t create a fire hazard. Modeling the electrolyte model specifically with gum in mind, the material is twice as sticky as real gum and adheres very well to the other battery components.

The material, which is a hybrid of liquid and solid, contains liquid electrolyte material that is hanging on solid particles of wax or a similar material. Current can easily travel through the liquid parts of the electrolyte, but the solid particles act as a protective mechanism. If the material gets too hot, the solid melts and stops the electric conduction, preventing fire hazard. The electrolyte material is also flexible and lightweight, which could be useful in future flexible electronics. It can be stretched, smashed, and twisted, but continues to conduct electricity nearly as well as liquid electrolytes.

While the researchers have shown good conductivity with their electrolyte, they hope to begin testing their idea soon in real batteries. The team was part of a group of WSU researchers that received support from the Washington Research Foundation last year to equip a battery manufacturing laboratory for building and testing lithium battery materials in commercial sizes. The research groups also are working together to combine their technologies into safer, flexible low-cost batteries.

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