Researchers at The Ohio State University (OSU) have unveiled a patent-pending design which combines a solar cell and a battery into a single device.
A report published in the Journal of the American Chemical Society says the design achieves 20 percent energy savings compared with traditional lithium-iodine batteries.
Yiying Wu, professor of chemistry and biochemistry at Ohio State, says the 20 percent comes from sunlight, which is captured by a unique solar panel on top of the battery.
Unlike previous solar panel designs which are mesh-like, the panel employed with the new battery is a solid sheet.
The battery is also different owing to the fact that it uses a water-based electrolyte within. It is an emerging class of batteries called aqueous flow batteries.
“The truly important innovation here is that we’ve successfully demonstrated aqueous flow inside our solar battery,” Wu said.
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According to Wu, the new battery is entirely compatible with the existing battery technology, environment friendly and easy to maintain.
Aqueous flow batteries are being considered the future of battery technology as they could theoretically provide affordable power grid-level energy storage someday.
Mingzhe Yu, lead author of the paper published in JACS and a doctoral student at Ohio State, says the solar flow battery design that the team has developed has the potential for grid-scale solar energy conversion and storage applications when its development is completed.
Earlier, Yu had designed solar panels out of titanium mesh which let air pass through to the battery. But the latest design employs a solid sheet solar panel as the aqueous flow battery doesn’t need air to function.
Another innovation applied in the battery design is a dye-sensitized solar cell. It is able to tune the wavelength of light best suited for capture and conversion to electrons.
The electrons thus released supplement the voltage stored in the lithium-anode portion of the solar battery.
And the battery uses a liquid electrolyte — lithium iodide as the salt, and water as the solvent — which offers high energy storage capacity with low cost.
Tests conducted by the researchers showed that the solar flow battery was able to produce output comparable with a typical lithium-iodine battery with less charging.
While a typical lithium-iodine battery has to be charged to 3.6 volts to discharge 3.3 volts, the solar flow batteries discharged around 3.3 volts.
In one test, the researchers charged two solar flow batteries 25 times at 2.9 volts and then discharged them. Each time, both batteries discharged around 3.3 volts.
The attached solar panel made up the difference, which is equivalent to energy savings of nearly 20 percent.
Solar flow battery researchers are working to further fine-tune the system to make it more efficient.
The team’s goal is to boost the solar cell’s contribution to the battery beyond the current 20 percent to even 100 percent.
Ajith Kumar S