Solar cells that can also store energy were revealed last October by the team from Ohio State University (OSU). The design was pretty unique- it had three electrodes instead of four, a lithium plate base, thin sheet of carbon separating the layers of electrodes, and a dye-sensitive titanium dioxide photoelectrode, which was kept inside a titanium gauze mesh. This set up used to have a conventional salt-solvent electrolyte, and required air in order to work, however it did not perform as well as they hoped.
The researchers behind it, did not give up on the technology, and only a few months later, they were already ready with the new-and-improved version. The new battery, which is now introduced in the current issue of the journal of the American Chemical Society, uses water instead of the solvent, and lithium iodide instead of the salt. It is the so-called “aqueous solar flow battery“, which can be easily topped with a single solid sheet that is the solar panel. The solar cells that were used in the earlier version, are still there, and they are ruthenium-sensitized (red-dye-sensitized), which adjust and fine-tune the wavelength of light.
The performance of the aqueous solar flow battery was tested against the commonly used lithium-iodine battery. The researchers repeated charge-discharge cycles 23 times and measured the release of electricity. The results were striking. The lithium-ion battery was charged to 3.6 volts and discharged 3.3 volts. To discharge the same 3.3 volts, the solar flow battery needed to be charged only to 2.9 volts, and the remaining 0.4 volts were made up by the solar cells.
As great as this is, the researchers think that they can make it even better. Making it more efficient, could eventually lead to a practical solution of a very pressing problem within the solar industry- that of energy storage. The team is convinced that their battery can easily be upscaled to grid-size. They also foresee application of their technology in solar-powered vehicles.
Image (c) Ohio State University