Magnesium batteries show mettle

Researchers from Bar-Ilan University in Israel have developed rechargeable batteries made from magnesium, a cheap, abundant and relatively environmentally friendly metal.

The batteries can be recharged as many as 3,000 times, lose power slowly, and have a working temperature range of -40 to 100 degrees Celsius. They are also safe and maintenance-free, making them good candidates for large-size applications like powerplant load-leveling, according to the researchers.

The key to making batteries that use magnesium as a positive electrode was finding suitable negative electrode and electrolyte materials. Batteries use a cycle of chemical reactions between positive and negative electrodes to release energy stored in the electrolyte. The researchers' prototype uses a molybdenum sulfide negative electrode and liquid and solid electrolytes of organic, or carbon-based, and organo-metallic compounds.

The batteries have an energy density of 60 Watt hours per kilogram, which is higher than existing nickel cadmium and lead acid batteries, but lower than lithium batteries. The researchers are working to increase the energy density of the batteries.

The batteries could be used in practical devices in two to five years, according to the researchers. The work appeared in the April 9, 2003 issue of Advanced Materials.