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New 'Iron' Battery Lasts 50 Percent Longer
by Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - A new iron-based battery not only lasts much longer than conventional batteries, but contains fewer toxic metals and is thus "greener" when thrown away, Israeli researchers said.

The new "super-iron" batteries are rechargeable and could be used anywhere from portable CD players to medical implants, the researchers wrote in the journal Science.

"Super-iron, compared to conventional alkaline batteries, have over 50 percent energy advantage, and in the important high-drain region provide a 200 percent higher energy capacity increase," lead researcher Stuart Licht of the Technion-Israel Institute of Technology in Haifa, Israel, said Thursday.

Licht defined a "high-drain rate" as the rapid use of the electrical energy stored in the battery such as in cameras, portable CD players and cellular phones.

"For example, a conventional AAA size alkaline battery may last only a few minutes at high drain rate, but under the same conditions an AAA super-iron battery discharges for well over an hour," added Licht. Licht's team said its patented batteries offer the first big change in battery technology since alkaline batteries were invented in 1860.

Licht said he was looking for a battery that lasted longer and worked better than standard batteries.

"I enjoy today's high-tech gadgets as much as anyone, yet they are wasteful of batteries," he said in an e-mail interview.

"I was specifically searching for materials to cut down on this wasteful disposal, compatible with existing battery systems, and which are environmentally 'clean' materials."

He said no one had tried to use iron in a battery for generations because it rusts so easily.

"We found we are able to stabilize them in the caustic solution commonly used in today's primary and metal hydride batteries," Licht said. "The caustic solutions not only stop the super-iron from decomposing, but are basically the same as that used in alkaline batteries and therefore excellent for electrical energy storage."

Licht said about 60 trillion primary batteries are used each year. Both dry and alkaline batteries use manganese dioxide and zinc.

"The new super-iron battery replaces the heaviest portion of these batteries (which is the manganese dioxide) with a very unusual material, super-iron, which has a much higher electrical energy storage," Licht said.

"These batteries appear to be suitable replacements for all alkaline batteries. The super-iron battery is rechargeable, and is a suitable replacement for rechargeables such as Ni-Cds (nickel-cadmium batteries)."

Batteries use chemical reactions to convert chemical energy from metals at its two electrodes, the positive cathode and the negative anode, into electrical energy. A battery dies when the metals at either electrode are used up.

Licht's "super-iron" is ferrate, an unusual form of iron combined with oxygen. It is usually unstable but he found that if it is kept very pure, it stays in a stable and usable form.

The batteries, which use either potassium ferrate or barium ferrate cathodes, release no toxic chemicals into the environment, unlike alkaline batteries, Licht said.

"The super-iron cathode eventually turns into environmentally "green" iron rust, which is preferable over the often poisonous compounds, varying from mercury, cadmium, manganese and nickel oxides that remain in many of the batteries presently used," he said.

12 August 1999