Fast charging solid state silicon battery spinout
A spin out of the Empa labs in Switzerland is looking to commercialise thin film solid state silicon battery technology.
BTRY is developing thin-film solid state silicon battery cells that are safer and longer-lasting than conventional lithium-ion cells but also more environmentally friendly to manufacture and can be charged and discharged in just one minute. The design is also insensitive to temperature fluctuations and the swelling of the silicon anode.
The battery cells are constructed using vacuum coating with the materials atomized in a vacuum chamber to form individual atoms, which are then deposited in a precisely controlled layer on the target substrate.
Each cell consists of an aluminium cathode current collector, an amorphous LiCoO2 (LCO) cathode, a Lipon solid oxide electrolyte, a silicon anode and a copper anode current collector, and the researchers have so far built a cell with two layers.
The battery can be cycled for more than 300 cycles between 6 and 8 V. Using a thermo-electric model, the researchers predict that stacked thin-film batteries can achieve specific energies >250 Wh kg−1 at fast chargin gC-rates above 60. This would provide a specific power of tens of kW kg−1 needed for high-end applications such as drones, robots, and electric vertical take-off and landing aircraft.
The solid state construction means the cell is safer. “If you cut our battery with scissors you will simply get two batteries that are half as good,” said Abdessalem Aribia, researcher at Empa and now CTO of BTRY. “We are convinced that our product can offer real added value,” says CEO Moritz Futscher.
“Such manufacturing methods are currently used on a large scale in the production of semiconductor chips and glass coatings,” Futscher says. “That’s an advantage for us, because the machines and know-how to manufacture our battery are largely in place already.” The startup currently uses equipment at Empa’s Coating Competence Centre in Dübendorf .
The high-precision manufacturing method is also more environmentally friendly. “In contrast to the traditional method of battery production, our method does not use toxic solvents,” said Aribia. However, it also makes the thin-film battery more expensive. The researchers therefore see its application primarily in products where the battery only accounts for a small part of the overall cost of the device such as smartwatches or satellites. “There, the advantages of our technology more than make up for the higher price,” said Aribia.
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Over the next two years, the researchers want to increase both the surface area of the battery and the number of layers. “Currently, our batteries consist of only two layers of about 1×3 millimeters,” says Aribia. “Next, we want to make a battery of about one square centimeter with two to three layers. We can’t power a satellite with that yet – but we can very well show that our technology is scalable.”
BTRY was supported by Innosuisse and made it into the business incubator of the European Space Agency (ESA). In addition, Aribia received an Empa Entrepreneur Fellowship, which supports young researchers who want to found a company.
Several other European companies have developed similar solid state battery technologies aiming at medical applications including Ilika in the UK and InjectPower in France.
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