A Japanese research institute says it may have come up with a nifty new solution to a key challenge facing developers of next-generation lithium-air batteries – clogging.

Researchers at Japan's National Institute of Advanced Industrial Science and Technology (AIST) report that they have come up with a way to separate the electrolytes within a lithium-air cell with a solid conductor glass film. That keeps solid byproducts from forming and clogging the air electrode, the researchers said.

The process could help solve a key challenge of lithium-air batteries, which like their zinc-air counterparts generate energy by exposing metal and an electrolyte to oxygen. The chemical process used to generate power is hard to reverse, in part because of the formation of solid materials that can clog the system.

It would be a good problem to solve, since lithium-air technology promises energy storage capacities of about 10 times those of lithium-ion batteries, according to backers.

AIST's researchers said their new experimental batteries could offer a tenfold or greater improvement on those other lithium-air technologies. But they also noted that "the lithium-air battery newly developed by AIST needs further technical improvement toward practical use."

The AIST researchers used an organic electrolyte containing lithium salt as the anode and an aqueous (water-based) electrolyte as the cathode, with a "lithium super-ion conductor glass film" in between.

The resulting byproduct wasn't a solid like lithium oxide, but a lithium hydroxide that dissolves in the water-based solution, avoiding the clogging that would come from a solid byproduct.

To avoid corrosion during recharging, the experimental battery would remove the water solutions with the dissolved byproduct from the system and replace it with fresh water-based solution.  

The result, researchers said, could be a car battery that can be "recharged" by removing the used aqueous gel solution and replacing it with fresh solution, as well as adding new cartridges of lithium salts for the anode side.

That would make the device more like a fuel cell than a traditional definition of a battery, in which materials aren't removed when it is recharged. That fuel cell concept sounds a bit like the product of Livermore, Calif.-based PowerAir Corp., which makes a zinc-air fuel cell that recharges by removing spent materials and adding fresh ones.

PowerAir, which is commercializing technology developed at Lawrence Livermore National Laboratory, is targeting the stationary market, however, with an eye to replace dirty diesel-fueled generators.

Other companies working on zinc-air batteries – which offer lower energy densities than lithium in exchange for using a far cheaper metal – include zinc-air battery developer ReVolt Technology, which announced this month that chemical giant BASF would help it commercialize its rechargeable zinc-air batteries (see Green Light post).

As for lithium-air batteries, Berkeley-based startup PolyPlus has developed what it calls "protected" lithium electrodes that don't chemically mix with the electrolyte to avoid the problems inherent in metal-air batteries.

And IBM's Almaden Research Center in San Jose, Calif., is seeking to apply water filtration technology it has developed to solve the lithium-air battery recharge challenge (see IBM Delves Into Lithium-Air Batteries, Water-Cooled Supercomputers).