@OhioState's Solar Battery - How KAir Energy Systems Solar Batteries might come to smartphones and Laptops

So rechargeable smartphones or Laptops with built in Solar Batteries that breath in oxygen to recharge? This innovation might be the next thing coming to the Apple iPhone 6S!

It might also make Solar Panels cheaper as you wouldn’t have to invest in Battery Backup to store excess energy generated when no-one is using electricity in the house.

A team at Ohio State University led by Chemistry Professor Dr. Yinying Wu has developed what is being billed as the world's first Solar Battery as reported in the article “A solar cell that stores its own power: World's first 'Solar Battery' runs on light and air”, published March 3 2014 by Pam Frost Gorder, Physorg. 

Their amazing breakthrough which was published in the October 2^nd 2014 issue of the Nature Communications Journal, was inspired by the teams past success in developing an Air battery whose power is based on the reaction of Potassium with Oxygen.

That same year, the team won a US$100,000 Clean Energy prize from the U.S. Department of Energy, which members of the team promptly used to set up a company called KAir Energy Systems, LLC to patent, license and market their battery design.

Their latest product, also funded by the U.S. Department of Energy, the Solar Battery is a hybrid combining the storage device with the power source, solar power. Because they're built together, in one manufacturing process, their technology represents an interesting way to lower the entry-level costs of going solar.

That’s because you no longer have to think about battery storage, to quote Chemistry Professor Dr. Yinying Wu: “The state of the art is to use a solar panel to capture the light, and then use a cheap battery to store the energy. We've integrated both functions into one device. Any time you can do that, you reduce cost”.

Because the Solar Cells are also the battery, the wiring losses between the external Battery Backup and the solar panels is reduced, as solar panel and battery are one and the same. So how did the team at Ohio State University achieve this marvelous feat? First, take a deep breath and grab some National bakery crackers and Guava Jam, as this is going to get complicated real fast!

Ohio State University Solar Battery - How KAir Energy Systems makes Solar Panels Cheaper and more Efficient

Armed with the previous success of the KAir battery, the research team realized that they had to find a way to make air flow though a Solar Panel. This was the initial design hurdle they encountered in modifying the KAir battery into a Solar Battery, which they solved in a rather interesting way; using a Mesh Solar Panel.

The Solar Battery works by first charging using this light from the Sun, which creates electrons, as in any solar panel. Those electrons are then used to decompose Lithium Peroxide (Li₂O₂) into Lithium ions (Li⁺) and Oxygen (O₂) as shown below:

Li₂O_2(s) + 2e^- → 2Li⁺_(s) + O_2(g)

The Oxygen (O₂) escapes into the air, leaving behind the Lithium Ion (Li⁺) in the Li-I battery holding onto the Charge, effectively stored for usage. In order to get that energy, Oxygen (O₂) from the outside is pumped through the battery, causing the reverse reaction that re-creates the Lithium Peroxide (Li₂O₂).

2Li⁺_(s) + O_2(g → Li₂O_2(s) + 2e^-

A Mesh Solar Panel was developed by Doctoral student Mingzhe Yu. He had some titanium drawn out as thin filaments and woven into a fine cloth-like fabric. Then using vacuum oxidization techniques, he then grew vertical rods of Titanium Dioxide (TiO₂) over the titanium cloth.

Then using the Mesh Solar Panel as the first electrode, they place a thin sheet of carbon below as the second electrode, albeit it really acts as more of an insulator to separate the two (2) active electrodes. This Solar Battery was finally completed with a third electrode that consists of a thin plate of powdered Lithium Peroxide (Li₂O₂), as pure Lithium is very reactive.

Completing the Solar Battery sandwich is looped cloth soaked in electrolyte, most likely silver iodide (AgI) in a complex with Sodium Chloride (NaCl). This provides extra electrons for the mobile ions in solution thereby making it easier to transmit charges between electrodes i.e. the Mesh Solar Panel and the thin plate of Lithium alloy, as shown below:

Because of its unique design, the normal four (4) electrode connections between a regular solar panel and battery was reduced to only three (3) electrodes:

1.      Positive

2.      Negative

3.      Common or Earth

Thanks to its reduced need for terminals and wiring because of its compact design, the Solar Battery worked increased the transfer of solar radiation to battery storage from 80% to close to 100%.

Solar Battery Improvements - A Little Rust makes Solar Battery go a long way

Interestingly the Mesh Solar Panel made of Titanium Dioxide (TiO₂) had to be attuned to red light, as its maximum radiation absorption only occurred in that spectrum of visible light.

This can be done by using a red filter made with a glass cover coated with a red dye that only passes red light through to the Mesh Solar Cells. It cans also be achieved by simply spraying on nano-particles of the red dye directly onto the semiconductor so that it only reflects red light and thus only absorbs light in that part of the visible spectrum.

Like typical solar panels, I suspect the finished Solar Battery, like regular Solar Cells will have the semiconductor sandwich sealed inside of a glass casing, making this Solar Batter a dye-sensitized solar cell.

The Researchers at the Ohio State University opted to use glass impregnated with Nano-particles of Ruthenium (Ru), somewhat like stained glass. This basically acts as a red light filter, so that the Mesh Solar Panel only absorbed red reflected light passed the Ruthenium (Ru) impregnated glass onto the Titanium Dioxide (TiO₂) forest growing on the Mesh Solar Panel.

Oddly, the Ruthenium became more reactive when exposed to sunlight, most likely transitioning to a different ionization state and thus resulting in scintillation effect when it began to produce a rainbow of other colours, a habit typical of transition metals when used in jewelry.

One of the researchers, doctoral Student Lu Ma, realizing that Ruthenium (Ru) was not stable when after eight (8) hours it began to show signs of transitioning when she examined it under an X-ray photoelectron spectroscopy.

So they had to unseal the Solar Battery and replace the glass filter impregnated with Ruthenium (Ru) with a glass filter impregnated with nano-particles of iron (II) oxide (FeO₂). This is also the same thing we generally call rust and was used by medieval glassmakers’ centuries prior to make red stained glass.

But drawing upon the wisdom of the Old Masters, they improved upon the lifespan of the rechargeable battery, which according to chemistry Professor Dr. Yinying Wu, makes it ready to hit the road in the next Laptop or Apple iPhone come 2017!