Army Researchers On the Hunt For Better Batteries

Credit: US Army

Scientists from the United States Army are working on creating a more efficient type of battery. In a new peer-reviewed publication from the American Chemical Society, researchers spoke at length about their efforts to improve current battery designs. The paper particularly focused on the team’s research regarding battery electrolyte structure and stability. The research was featured in a special issue of Accounts of Chemical Research, which was devoted to celebrating “the investigation of electrical energy storage over multiple length scales.”

“Lithium-ion batteries dominate energy storage for portable electronics and are penetrating automotive and grid-storage applications. Further progress depends not only on the development of a new high capacity electrode, but also on tailoring electrolytes in order to support fast and yet reversible lithium transport through the bulk electrolyte and across interfaces.”

Dr. Oleg Borodin, US Army Research Laboratory

Batteries rely on electrolytes in order to function. Electrolytes are a substance that is stuck between positive and negative electrodes. They conduct electric current in ionic form, while at the same time insulating any electron current. It’s the electrolyte’s properties that determine the speed at which a battery can deliver power, how long the battery can last, and how quickly it can absorb a charge.

In order to achieve electrochemical stability (the factor that determines the length of a battery charge), one of two factors has to be met. According to the team, the electrolytes need to be thermodynamically stable with electrodes. If that is not achieved, the electrolytes have to form a stable passivation layer. The layer should be electronically insulating, but also ionically conducting. At the same time it needs to accommodate mechanical stresses. This is due to the electrode volume changes that occur during battery cycling.

This isn’t the first such battery-based innovation by the team. Over the years, it has created a plethora of battery and electrolyte innovations. These include high-voltage aqueous electrolytes, produced in collaboration with scientists from the University of Maryland’s A. James Clark School of Engineering. And their work has not gone unappreciated: in 2017, the team was honored by the laboratory with the ARL Award of Science for their innovative work on 4-volt aqueous Li-ion Batteries.

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