Light energy stored in a battery at last


The problem with solar power is storing it. Unless you use connection to an electricity grid, the power has to be used immediately in your watch or a road sign. Now the chemists of Ohio State University have produced the first solar battery. A solar panel allows air to enter the device through a mesh so that a titanium dioxide gauze photoelectrode can combine with an oxygen electrode to charge a lithium-oxygen battery.

A triiodide/iodide shuttle is coupled with the electrodes to produce triiodide ions on the photelectrode which oxidise lithium peroxide. This means that in layman terms, the lithium-oxygen battery’s problem of overpotential is overcome at last by chemical oxidisation. Of course the aim has also been to cut costs, and this has been achieved, so far by 25%. Normally there is also a loss of energy (electrons) in the transition from solar cells to external batteries. By including the battery in the cell, almost 100% of the electrons make it to the battery and recharge it.

This is a breathing battery, according to Professor Wu, the professor of chemistry and biochemistry at the university. It even breathes out when it breaks down lithium peroxide into the metal. The titanium gauze has 200 micrometre holes with rods of titanium dioxide grown across them like grass b lades. Oxygen from the air can easily pass through. The lithium part of the battery is a thin plate, underneath a porous carbon sheet and layers of iodide electrolyte.

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