Water-in-salt electrolyte boosts energy density

Li-ion Batteries 18650 - Pouch Cell (Charged EVs)

Researchers at the University of Maryland (UMD) and the US Army Research Lab (ARL) are collaborating on a new type of lithium-ion battery that uses a high concentration of salt in an aqueous electrolyte. They hope to develop a battery that offers greater energy density and better safety than current designs.

“Lithium-ion batteries raise safety, environmental, and cost concerns, which mostly arise from their nonaqueous electrolytes,” write Liumin Suo and colleagues. “The use of aqueous alternatives is limited by their narrow electrochemical stability window (1.23 volts), which sets an intrinsic limit on the practical voltage and energy output. We report a highly concentrated aqueous electrolyte whose window was expanded to ~3.0 volts with the formation of an electrode-electrolyte interphase.”

The researchers demonstrated a full lithium-ion battery of 2.3 volts that cycled up to 1,000 times, with nearly 100% coulombic efficiency at both low (0.15 coulomb) and high (4.5 coulombs) discharge and charge rates.

The group’s initial findings, published in Science last November, won backing for a second phase of research, which will begin soon with $4 million in funding for three years. The researchers hope to lower the cost of the electrolytes, enhance energy density and cycle life, and bring out a commercial demonstration cell. Battery firms Liox and Saft will cooperate on commercializing aqueous batteries for use in EVs.

 

Source: University of Maryland via Green Car Congress