Army researchers improve battery safety with new cathode chemistry

May 10 (UPI) -- Scientists with the U.S. Army have developed a new type of cathode chemistry that makes batteries safer and more efficient.

Currently, soldiers must regularly carry batteries weighing between 15 and 20 pounds. But thanks to a new type of cathode and electrolyte, soldiers could soon be carrying safer and more efficient batteries weighing half as much.

Army researchers were able to boost lithium-ion battery energy density by using a totally aqueous electrolyte. The electrolyte is free of transition metal and boasts high capacity energy storage.

"Such a high energy, safe and potentially flexible new battery will likely give the Soldiers what they need on the battlefield: reliable high energy source with robust tolerance against abuse," Kang Xu, senior scientist at the U.S. Army Combat Capabilities Development Command's Army Research Laboratory, said in a news release. "It is expected to significantly enhance the mobility and lethality of the Soldier while unburdening logistics requirements."

By using a completely aqueous electrolyte, researchers were able to pair high-voltage cathodes with low-potential graphite anodes. The new type of anodes enabled halogen conversion-intercalation chemistry.

"The energy output of water-based battery reported in this work is comparable to ones based on flammable organic liquids other than water, but is much safer," said lead researcher Chunsheng Wang. "It gets about 25 percent extra the energy density of an ordinary cell phone battery."

The successful pairing of a graphite-salt composite cathode with a pure graphite anode allowed scientists to keep their battery free of flammable and toxic elements, including cobalt and nickel.

Researchers suggest their new battery chemistry -- detailed this week in the journal Nature -- could be used in situations where battery safety is a priority, such as on airplanes or spacecraft.

"This work is mainly about a brand-new concept of Li-ion cathode chemistry, using the redox reactions of halogens -- Br and Cl in this case -- to store charges, and using their intercalation nature to stabilize their strong oxidizing products inside the interlayer of graphite, forming dense-packed graphite intercalation compounds," Yang said.