Nanotech

An electric car being charged. / Photo by: MikesPhotos via Pixabay

 

The efficiency of electric-powered vehicles depends on how many miles it can travel on a single charge. To improve the performance of the batteries, scientists at the University of Maryland developed a fluorine-based electrolyte for lithium-ion power cells.

According to the scientists, the current lithium-ion batteries for electric cars reach their natural limit based on the number of charges packed in a given space. This can reduce the maximum performance of the vehicle. Thus, the team created an electrolyte formulation with fluorine to increase the battery capacity. However, the electrolytes are aggressive and must be stabilized to prevent potential dangers.

"We have created a fluorine-based electrolyte to enable a lithium-metal anode, which is known to be notoriously unstable, and demonstrated a battery that lasts up to a thousand cycles with high capacity," explained Xiulin Fan and Long Chen, co-authors of the study.

In order to stabilize the electrolytes, the scientists collaborated with Chunsheng Wang, a professor from the department of chemical and biochemical engineering at A. James Clark School at UMD. Wang analyzed every variation of the chemical structure of the components that can be useful or harmful in a battery.

To test the performance of the new formulation, they applied the electrolytes to produce a coin-cell shape battery, similar to the ones used in watches. After that, they made contact with industry partners to use the formulation for a high voltage battery.

Initial results showed that the new batteries can charge and discharge several times without losing its reliability and high supply of energy. Moreover, the batteries still perform with 93 percent of its capacity even after a thousand charge cycles. But the power cells displayed problems with other battery components, such as lithium-metal anode and high-voltage cathode materials. The electrolytes have the tendency to consume any other elements partnered with it.

“You can find evidence from literature that either support or disapprove fluorine as a good ingredient in interphases. What we learned in this work is that in most cases it is not just what chemical ingredients you have in the interphase, but how they are arranged and distributed,” Xu added.

Wang and Xu have started the Center for Research in Extreme Batteries to continue working on the new formulation. The research group is also open to companies who have a need for batteries with unusual applications.