Case Western University: Using Solar Cells (Energy) to Charge a lithium-ion Batteries for Electric Vehicles


Berkley Electric Cars iStock_EV-small-628x418Consumers aren’t embracing electric cars and trucks, partly due to the dearth of charging stations required to keep them moving. Even the conservation-minded are hesitant to go electric in some states because, studies show, if fossil fuels generate the electricity, the car is no greener than one powered with an efficient gasoline.

Charging cars by solar cell would appear to be the answer. But most cells fail to meet the power requirements needed to directly charge lithium-ion batteries used in today’s all-electric and plug-in hybrid electric vehicles.

Researchers at Case Western Reserve University, however, have wired four perovskite solar cells in series to enhance the voltage and directly photo-charged lithium batteries with 7.8 percent efficiency–the most efficient reported to date, the researchers believe.

The research, published in the Aug. 27 issue of Nature Communications, holds promise for cleaner transportation, home power sources and more.

“We found the right match between the solar cell and battery,” said Liming Dai, the Kent Hale Smith Professor of macromolecular science and engineering and leader of the research. “Others have used polymer solar cells to charge lithium batteries, but not with this efficiency.”

In fact, the researchers say their overall photoelectric conversion and storage outperformed all other reported couplings of a photo-charging component with lithium-ion batteries, flow batteries or super-capacitors.

Perovskite solar cells have active materials with a crystalline structure identical to the mineral perovskite and are considered a promising new design for capturing solar energy. Compared to silicon-based cells, they convert a broader spectrum of sunlight into electricity.

In short order, they have matched the energy conversion of silicon cells, and researchers around the world are pursuing further advances.

Perovskite Film adma201304803-gra-0001-m

Dai’s lab made multilayer solar cells, which increases their energy density, performance and stability. Testing showed that, as desired, the three layers convert into a single perovskite film.

By wiring four lab-sized cells, about 0.1 centimeter square each, in series, the researchers further increased the open circuit voltage. The solar-to-electric power conversion efficiency was 12.65 percent.

To charge button-sized lithium-ion batteries, they used a lithium-ion-phosphate cathode and a lithium-titanium-oxide anode. The photoelectric conversion and storage efficiency was 7.8 percent. Through 10 photo-charge/galvanostatic (steady current) discharge cycles lasting nearly 18 hours, the technology maintained almost identical discharge/charge curves over all cycles, showing high cycling stability and compatibility of the components.

“We envision, in the not too distant future, this is a system that you could have at home to refuel your car and, eventually, because perovskite solar cells can be made as a flexible film, they would be on the car itself,” said Jiantie Xu, who, with Yonghua Chen, is an equally contributing first author of the study. Both are macromolecular science and engineering research associates in Case School of Engineering.

The researchers are developing small-scale prototypes and working to further improve the perovskite cell’s stability and optimize the system.

 

Story Source:

The above post is reprinted from materials provided by Case Western Reserve University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jiantie Xu, Yonghua Chen, Liming Dai. Efficiently photo-charging lithium-ion battery by perovskite solar cell. Nature Communications, 2015; 6: 8103 DOI: 10.1038/ncomms9103

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Tesla Motors CTO: Energy Storage Tipping Point Within 10 Years: One-MIllion EV Cars and 70 Giga-Watt Hours of Storage + Video


tesla-motors-gigafactory-statistics-from-feb-2014-presentation_100457895_lTesla Motors CTO JB Straubel was the headliner at Intersolar North America last week. He talked about the transition to lithium-ion batteries and how that opened the floodgates for electric cars and stationary storage (eventually); the synergy between EVs, solar, and grid storage; the growth of solar power and grid storage; blah blah blah.

I know, I actually love all that stuff as much as the rest of you — it’s what I read, edit, & write about every day(!) — but it’s basically all general history and trends we know all about. But then JB dropped the awesome-bomb:

“I think we’re at the beginning of a new cost-decline curve, and, you know, this is something where there’s a lot of similarities to what happened with photovoltaics. Almost no one [would have predicted] that photovoltaic prices would have dropped as fast as they have, and storage is right at the cliff, heading down that price curve. It’s soon going to be cheaper to drive a car on electricity — a pure EV on electricity — than it is to drive a gasoline car. And as soon as we see that kind of shift in the actual cost of operation in a car that you can actually use for your daily driver, you know, from all manufacturers I believe we’re going to see electric vehicles come to dominate the whole transportation fleet.

“Also, that same battery cost decrease is going to drive batteries in the grid. There’s going to be much faster growth of grid energy storage than I think most people expected. You suddenly get to have energy that’s 100% firm and buffered from photovoltaics that’s cheaper than fossil energy. And we’re within sort of grasping distance of that goal, which is very, very exciting.Tesla Home 050815 _1x519_0

“Because once we get to that, and there really is no going back, it will make sense to do this economically without any environmental consideration whatsoever. So that’s the amazing tipping point that’s going to happen within I’m quite certain the next 10 years.”

The next 10 years!

Word.

Mic drop.

(Though, he didn’t actually drop the mic.)

You can watch the highlights via Intersolar on YouTube — video below:

Intersolar North America Conference Opening 2015

Another great quote, however, was this gem: “It’s not going to be many years before Tesla will have a million cars, or 70 gigawatt-hours of storage.” (That quote wasn’t in the highlight video above for some reason!)

Berkley Electric Cars iStock_EV-small-628x418One million cars. Can you imagine? Will you have a Tesla by then?