'Super-iron' battery shows great potential - 26 Jan 2000

Researchers at Technion-Israel Institute of Technology in Haifa, Israel, are developing a new battery that looks set to replace conventional alkaline and NiCad batteries. The patented batteries are said to offer the first big change in battery technology since alkaline batteries were invented in 1860.

Cheap, nontoxic

Iron, being the second-most common metal in the earth's crust, is also one of the cheapest. The new battery promises to be far more environmentally friendly than the currently popular alkaline and NiCad cells. The super-iron cathode eventually turns into 'environmentally friendly' iron rust, which is preferable over the often poisonous compounds, including mercury, cadmium, manganese and nickel oxides that remain in many of the batteries that are used presently. This natural tendency to turn to rust is what has prevented battery designers from considering it as a sensible choice.

The super-iron part is the 'ferrate' in the potassium ferrate or barium ferrate which replaces the heaviest portion of the older batteries (the manganese dioxide). This iron-oxygen compound is in a form that is very unstable under normal circumstances. The Fe(VI) ions are missing six of their electrons - this would normally cause the iron to turn to rust rapidly on being exposed to the elements. The caustic environment inside the cell preserves the super-iron, where it performs its role as a cheap and effective cathode.

Performance

This results in a chemical combination that is potentially able to store more energy than conventional alkaline cells. The reported capacity is around 50% higher than typical alkaline cells (13 August issue of the journal Science). Besides promising greater energy storage capacity, the new technology also shows signs of performing very well under high load conditions. Current batteries ex- hibit a significant loss of capacity when operating under high load conditions, the new battery appears to be less affected by a high rate of discharge. This is something that model car and aircraft enthusiasts might look forward to. The cells will look the same as standard AAA, AA, C and D cells.

Around 60 billion alkaline cells are disposed of all around the world every year. The potential for relief on the environment, together with the lower cost and the performance of this new technology seems to leave no doubts as to the sense in pursuing its development.

There are still aspects that require further testing, such as the shelf life, how many charging cycles they will endure, etc. So do not rush out and look for them yet - it may be some time before development reaches the commercially viable stage.