Scientists Unveil New ‘Super’ Battery
Experimental batteries based on an unusual form of iron deliver 50% more energy than regular batteries and decompose to nothing more threatening than rust, researchers in Israel reported Friday.
The researchers also developed a modified version of the cell that is 75% rechargeable. Experts hailed the discoveries as intriguing but remain uncertain about the practical applications.
Batteries now on the shelves always run out of one of three important components while they still have plenty of the other two. Researchers at the Technion Israel Institute of Technology solved that problem by using a different material for that one limiting component.
Batteries provide convenience and mobility, powering everything from flashlights and stereos to hearing aids and talking toys. Consumers in the United States used 4 billion batteries last year, according to statistics from the makers of the Energizer battery. This translates to about $1.3 billion in non-rechargeable batteries in this country.
With such a large market, the drive to develop new battery technologies is strong, and has resulted in such advances as batteries that can be reused. But non-rechargeable batteries still power the bulk of consumer electronics and, surprisingly, the dominant battery type (the alkaline battery) relies on the same chemistry that has been used for more than a century.
The secret of the new battery’s extra power, reported in Friday’s issue of the journal Science, is a new chemistry.
A battery’s three components are the anode, the cathode and the electrolyte, which allows current to flow between the anode and cathode. Electrons build up on the anode; when the battery is installed in a device, those electrons flow through the device to the cathode, powering the device. As this happens, the material at the anode changes to a form that cannot give up more electrons, and the material at the cathode changes to a form that cannot take any more electrons. Typically, the cathode is exhausted long before the anode or electrolyte.
Whereas traditional cathodes contain a chemical called manganese dioxide, the new batteries rely on what head researcher Stuart Licht dubbed a “super iron” because of its enhanced ability to store a charge and provide more juice.
Another advantage, Licht said, is that a spent super-iron battery contains relatively harmless materials. As the battery is used, the super-iron is processed into a form of ferric oxide: rust. For traditional batteries, the manganese dioxide turns into a somewhat poisonous chemical called manganese sesquioxide, though the material is trapped within the battery shell.
Researchers also developed a rechargeable version, which uses the super-iron cathode and an anode of the same material as in other rechargeable batteries. This is also a significant improvement over current technology, according to Licht.
He declined to comment on the commercial ramifications of the study, other than to say that “it is always the dream of the inventor to see his invention come to fruition and be useful to society.”
Duracell spokeswoman Ann Davin confirmed that Duracell is investigating Licht’s super-iron technology. “We believe a great deal of [research and development] would be required before we could get a consumer-viable product,” she said. “[However], we think it’s worth considering.”
Super iron wasn’t previously considered as a possible battery material because it was believed to be very unstable, decomposing in a short time to rust. Clearly, material with a short shelf life would make a poor battery. The cause of the speedy decomposition appears to be contaminants in the iron; the materials in Licht’s battery were carefully prepared to contain few contaminants. Also, the caustic electrolyte stabilizes the iron.
Licht believes his batteries could stand the test of time: They were extremely stable for a month and should last well.
Not everyone is convinced. Some scientists assert that the only way to see if a battery lasts for years is to make one and then test it years later.
Also, the wary point out, there is a significant difference between producing a single battery in a laboratory and producing billions of batteries in a factory. Synthesis of the super iron might be difficult to do on a large scale, for example. Davin also notes that the battery must perform over a wide range of temperatures, have a long shelf life and be economically feasible to produce.
“It’s a discovery that’s very interesting. Whether the materials will ever be commercially viable is still a question,” said professor Jeff Dahn of Dalhousie University in Halifax, Canada, who works on innovative battery technologies. “But it shows scientists around the planet the importance of the search for better battery materials.”
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More Juice, Please
A new type of battery is powered by a cathode made of an unusual form of iron that absorbs more electrons, boosting the battery’s power and providing
50% more power.
How a Battery Works
A battery stores chemical energy and converts it into electrical energy. Within its casing, it consists of two electrodes, a separator to keep the electrodes from coming in contact with each other and an electrolyte to allow ions to flow between them. A battery has a negative and a positive end. Electrons collect on the negative terminal and, when a circuit is completed, flow to the positive terminal.
Sources: Israel Institute of Technology; CD Innovations
