Materials and Cost Benchmarking

Sticky Electrolyte Makes for Safer Li-Ion Battery

10 February 2014

Researchers at Washington State University (WSU) have developed a gum-like lithium battery electrolyte that works as well at conducting electricity as a liquid electrolyte but doesn’t create a fire hazard.

Electrolytes allow for the movement of ions between the anode and the cathode to create electricity. But the liquid acid solutions can leak and even create a fire or chemical burn hazard.

Protective measures such as adding temperature sensors or flame retardant additives “can’t solve the safety problem fundamentally,’’ according to Katie Zhong, Westinghouse Distinguished Professor in the School of Mechanical and Materials Engineering.

Commercially available rechargeable lithium batteries are able to store a large amount of energy compared to other batteries. Their biggest potential risk, however, comes from the electrolyte in the battery, which is made of either a liquid or gel and can be a fire or chemical burn hazard if leaked.

Solid electrolytes can address safety concerns, but they don’t conduct electricity well and it is difficult to connect them physically to the anode and cathode. The research team looked for a material that would work as well as liquid and could stay attached to the anode and cathode “like when you get chewing gum on your shoe,’’ according to Zhong.

Graduate research student Yu Wang designed an electrolyte model specifically with gum in mind. It 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 easily stops the electrical conduction, preventing any fire hazard.

The electrolyte material is also flexible and lightweight, which could be useful in future flexible electronics. It continues to conduct electricity nearly as well as liquid electrolytes even when stretched, smashed and twisted.

The gummy electrolyte should be easy to assemble into current battery designs, said Zhong. They hope to begin testing their idea soon in real batteries.

Zhong’s group 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 researchers have filed a patent and have reported on their work in the journal Advanced Energy Materials.

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