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Energy Storage

Tesla lays out battery advances

To reduce costs by half, the carmaker pledges changes from mine to factory

by Melody M. Bomgardner
September 26, 2020 | A version of this story appeared in Volume 98, Issue 37


This photo is a still image from Tesla's presentation on how metal powder is deposited on the cathode metal foil.
Credit: Tesla
In a presentation about producing cheaper batteries, Tesla showed how it would use powdered metal compounds to make its cathodes.

Investors attending Tesla’s recent drive-in battery technology day in Fremont, California, honked their approval of coming innovations that executives promised would cut the price of electric-vehicle batteries more than 50% over the next 3 years.

CEO Elon Musk, with help from Drew Baglino, Tesla’s head of powertrain and energy engineering, told those who watched online or from their cars that changes in how battery cells are made will enable Tesla to sell electric vehicles for $25,000.

“One of the things that troubles me most is we don’t yet have a truly affordable car,” Musk said.

Tesla currently buys battery cells from Panasonic, LG Chem, and Contemporary Amperex Technology. The company plans to bolster its supply and reduce costs by getting into cell design and manufacturing. Musk laid out an ambitious plan to make 3 TW worth of batteries per year—20 times the output of a modern battery factory.

Tesla plans a larger cell that includes fundamental changes to both the anode and cathode. Like other battery manufacturers, Tesla is keen to use silicon in its anodes because the metal can store nine times as many lithium ions as traditional graphite. But when charged, silicon expands significantly and sometimes causes the anode to crack.

Baglino said Tesla will use standard metallurgical silicon rather than pricey nanostructured materials in its anode design and combat expansion with stretchy ion-conducting polymer coatings and binders. Using silicon, he said, will expand the range of electric vehicles 20%.

Tesla’s cathodes will feature nickel rather than the cobalt in today’s cathodes. Nickel is cheaper than cobalt and provides higher energy density. Tesla intends to use novel coatings and dopants to achieve the stability cobalt normally provides. Battery cells with very high nickel content will end up in the firm’s semitrucks and its futuristic-looking Cybertruck.

To further reduce costs and speed manufacturing, Baglino wants to change the way metals are mined and then deposited on metal foils to form battery electrodes. One advance will be to bypass the conventional nickel and lithium sulfate intermediates and go straight to the desired form of those metals. Tesla also intends to obtain lithium from its own clay deposits in Nevada.

Finished electrodes are normally made by mixing metal powders with solvent and applying them to the foils. Tesla is developing technology to apply the powder directly, eliminating many mixing, spraying, drying, and solvent-recovery steps. The traditional method “is like digging a ditch and then filling it in,” Baglino quipped.

Musk tempered expectations by saying many of the battery innovations are still works in progress at Tesla’s Fremont pilot plant. That could give competitors a window to improve their own products or achieve breakthroughs such as solid-state batteries, warned Joseph Spak, a stock analyst at RBC Capital Markets, in a note to investors.



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