Lithium Ion battery that runs on Salt Water?

Army, UMD researchers develop water-based lithium-ion batteries that don't explode

Researchers at the U.S. Army Research Laboratory and the University of Maryland have developed for the first time a lithium-ion battery that uses a water-salt solution as its electrolyte and reaches the 4.0 volt mark desired for household electronics, such as laptop computers, without the fire and explosive risks associated with some commercially available non-aqueous lithium-ion batteries.

From article, (Researchers at the U.S. Army Research Laboratory and the University of Maryland have developed for the first time a lithium-ion battery that uses a water-salt solution as its electrolyte and reaches the 4.0 volt mark desired for household electronics, such as laptop computers, without the fire and explosive risks associated with some commercially available non-aqueous lithium-ion batteries.

Their work appears Sept. 6, 2017, in Joule, Cell Press's new interdisciplinary energy journal.

This technology will bring the Soldiers a "completely safe and flexible Li-ion battery that provides identical energy density as the SOA Li-ion batteries. The batteries will remain safe -- without fire and explosion -- even under severe mechanical abuses," said co-senior author Dr. Kang Xu, ARL fellow who specializes in electrochemistry and materials science.

"In the past, if you wanted high energy, you would choose a non-aqueous lithium-ion battery, but you would have to compromise on safety. If you preferred safety, you could use an aqueous battery such as nickel/metal hydride, but you would have to settle for lower energy," Xu said. "Now, we are showing that you can simultaneously have access to both high energy and high safety."

The research follows a 2015 study in Science journal that produced a similar 3.0 volt battery with an aqueous electrolyte but was stymied from achieving higher voltages by the so-called "cathodic challenge," in which one end of the battery, made from either graphite or lithium metal, is degraded by the aqueous electrolyte. To solve this problem and make the leap from three volts to four, the first author, University of Maryland assistant research scientist Chongyin Yang, designed a new gel polymer electrolyte coating that can be applied to the graphite or lithium anode.

This hydrophobic coating expels water molecules from the vicinity of the electrode surface and then, upon charging for the first time, decomposes and forms a stable interphase -- a thin mixture of breakdown products that separates the solid anode from the liquid electrolyte. This interphase, inspired by a layer generated within non-aqueous batteries, protects the anode from debilitating side reactions. This allows the battery to use desirable anode materials, such as graphite or lithium metal, and achieve better energy density and cycling ability.)