Battery start-up boosts energy density 2-fold on lithium-ion cells - Embedded.com

Battery start-up boosts energy density 2-fold on lithium-ion cells

Sakti3, Inc. (http://sakti3.com/), a University of Michigan startup has just announced that it has produced a lithium-ion battery cell on fully scalable equipment that delivers over 1100 Watt hours per liter (Wh/l) in volumetric energy density.

According to Dr. Ann Marie Sastry, CEO of Sakti3, this translates to more than double the usage time in a wearable device like a smartwatch, from 3.5 to more than 9 hours. It also translates to almost double the range in an electric vehicle (EV) like the Tesla Model S, from 265 mi to 480 mi.

“It’s clearly a breakthrough – it’s a world’s best, made on a mass-production platform,” said Professor Wei Lu from the University of Michigan, a battery expert knowledgeable about the process. “It’s not either/or in cost and performance in batteries anymore – Sakti3 has both.

“They built a really high performance device on a really low cost platform – like building millions of high end processors in a factory that produces ordinary plastic wrap. It was quite a scientific feat.”

Sastry said that the company demonstrated over 1000 Wh/l on a prototype over two years ago, and has since moved to a pilot tool, using all scalable materials and equipment. The technology development was guided by mathematical simulations, starting with materials, and continuing to full scale plant layout to avoid any high cost materials, equipment or processes.

The solid-state battery has been produced with a thin-film vacuum deposition process similar to that used for making flat panel displays and photovoltaic solar cells. In several respects, though, it is significantly different than the lamination process used in most lithium-ion batteries.

in the traditional approach chemical powders are blended into a wet slurry which is coaded onto metallic film sheets. These are then sliced segments of appropriate size and placed in pouches with the electrolyte and other components.

The approach Sakti3 uses instead is a solid state process that takes place in a vacuum where the layers of the thin-film battery are deposited sequentially, starting with the cathode, follwed by the current collector, then the interlayer, anode, …and so on.

The cell contains no liquid electrolyte and makes use of an interlayer that does double duty: as a separator to keep the positive and negative electrodes from coming into contact, and as the electrolyte that facilitates ion transfers that are necessary to the battery operation.

An advantage of the approach Sakti3 is using is that because solid-state does not have any aging requirements and cells come out fully charged and ready to test. By contrast current approaches need 30 to 60 days

Sastry said that along with having an ultra-low cost solution, the battery cells are also the safest ever demonstrated because of the all-solid-state construction and materials in the cells.

Sakti3's battery is an outgrowth of amost a decade of work by Sastry and her colleagues at the University of Michigan and grew out of investigations, using complex mathematical optimization algorithm to understand the inter-relationships between the many variables that go into an electric car battery—energy, power, mass, volume, cost, safety. That analysis indicated that liquid electrolyte found in conventional lithium-ion batteries was the wrong way to go for because of a variety of safety, production, lifetime and packaging limitations.

”Our target is to achieve mass production of cells at ~$100/kWh,” said Dr. Sastry. “Our key patents on the technology have been issued, we are up and running on larger tooling, and can now speed up processing. Our first market will be consumer electronics, and after that, we’ll move to other sectors.”

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