We often overlook the advances in technology that come from military research. The direct forerunner of autonomous cars and trucks was the competition sponsored by DARPA in the Mohave Desert, for instance. Global positioning technology was originally developed for the military, as was the internet. And the space program gave us Tang and mylar blankets.
Power is vital to any military operation. More American soldiers were killed in Iraq transporting gasoline and diesel fuel than in actual combat. The military is interested in solar energy so soldiers can operate independently anywhere in the world without the constraints imposed by supply lines.
Today’s soldiers carry many electronic devices with them in the field — night vision glasses, radios, computers, and satellite tracking devices, to name a few. Keeping all those systems powered up means lugging around lots of batteries, sometimes as much as 25 pounds of them. Making lighter, more energy dense batteries would free soldiers from some of that burden.
Researchers at the Army Research Lab in Adelphi, Maryland report they have created lighter batteries with high energy density that use no flammable electrolyte and operate without cobalt or nickel in their chemistry. If the breakthrough can be proven to be stable and durable in real world conditions outside the lab, the implications for batteries for everything from cell phones to electric vehicles to grid scale energy storage could be significant.
“Such a high energy, safe and potentially flexible new battery will likely give the soldiers what they need on the battlefield: a reliable high energy source with robust tolerance against abuse. It is expected to significantly enhance the mobility and lethality of the soldier while unburdening logistics requirements,” says Dr. Kang Xu, an ARL fellow and senior research chemist. The research was published recently in the journal Nature.
“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,” says lead author Chongyin Yang. “It gets about 25% extra energy density of an ordinary cell phone battery. The new cathode is able to hold, per gram, 240 milliamps for an hour of operation, whereas the kind of widely used cathode in cell phones, laptops, and tools provides only 120-140 milliamps each hour per gram.”
The research has gotten the attention of noted battery expert Jeff Dahn of Dalhousie University in Canada. Dahn is a principle adviser on battery technology for Tesla. “The paper by the University of Maryland and the Army team is the most creative new battery chemistry I have seen in at least 10 years,” he says. “The fact that the LiCl and LiBr reversibly convert and form halogen intercalated graphite is truly incredible.
“The team has demonstrated encouraging reversibility for 150 cycles and have shown that high energy densities should be attainable in 4-volt cells that contain no transition metals and no non-aqueous solvents. It remains to be seen if a practical long-lived commercial cell can be developed, but I am very excited by this research.”
Professor Gleb Yushin of Georgia Tech, who was not involved in the research, agrees.
“In their paper, Wang et al. demonstrated an absolutely remarkable progress in their development of nonflammable aqueous Li-ion batteries by simultaneously increasing cell voltage and utilizing cobalt-free and nickel-free cathodes.
“In contrast to traditional intercalation cathodes based on rare, expensive, and rather toxic transition metals such as cobalt and nickel, researchers demonstrated excellent cycle stability in a graphite-salt composite cathode coupled with a pure graphite anode. Their innovative solution enables the use of cheaper and environmentally safer graphite as a higher gravimetric capacity cathode that operates at a higher average voltage than state of the art.
“In yet another contrast to traditional Li-ion where Li ions do all the work, the new cells utilize both Li cations and halogen anions for charge storage. Overall, this work reports on multiple key milestones for aqueous ion batteries and provides a major leap towards their commercially viable use in stationary storage and possibly even electric transportation applications.” – Yushin
There are reports of new battery breakthroughs almost daily. This one sounds like it could be the real deal. Not quite the solid state battery everyone is dreaming of, but a significant step forward in the drive to electrify everything in order to limit the ravages of a warming planet.
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