SF Technotes

A New Battery Will Reshape Tesla

By Michael Castelluccio
November 19, 2020
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On September 22, 2020, a gathering of Tesla shareholders parked their cars down the street from the Fremont, Calif., factory, presenting an image of a most rarefied drive-in show—all Teslas and no concession stand. There were those who were hoping for an update or an actual sample of the long-promised “million-mile” battery with a life span of 10 years, but that didn’t happen.

 

The event was billed as the 2020 Annual Meeting of Stockholders plus “Battery Day.” What was presented at Battery Day was a long-range view of Tesla’s future, starting with a newly designed Lithium-ion battery for electric vehicles (EVs). It was mostly engineering and projected costs and savings, but if there was a theme, as engineer Ricky Roy put it, it was Elon Musk expressing his hope for creating the best manufacturing company in the world. And if there is such a thing as holistic manufacturing, Musk seems to have an idea of how to proceed.

 

The new EV battery that he was introducing would, he explained, require a separate factory for its production. The company would begin a lithium mining operation in Nevada. It would change manufacturing processes at the main factory with the pressing of an entirely new under chassis to integrate the battery carrier. And Tesla will initiate research and development in lithium battery recycling. All the changes are energized by a radical new design for an EV cell, and all are directed toward the ultimate goal of a sustainable transportation model.

 

EV BATTERIES

 

Current Tesla batteries have three inherent drawbacks. Increasingly, they need to be more powerful and better able to sustain a charge. They generate too much heat. And there aren’t enough of them to provide an uninterrupted supply to allow for expanding production. Panasonic makes the Tesla batteries at Tesla’s Gigafactory in Nevada. The company also gets additional stock from CATL in China, LG Chem in South Korea, and others. Panasonic’s CEO Kazuhiro Tsuga has said the supply won’t be able to keep up with current expansion of production. He predicts a shortfall by 2022.

 

On Battery Day, Elon Musk announced Tesla has built a pilot battery production facility at its Fremont factory, and that it plans to make its own Lithium-ion batteries. He explained that the line isn’t yet in operation and will take about a year to reach scale production. The annual goal for the facility is to produce 10 gigawatt-hours per year (Musk used the term terawatt-hours). Current battery production in Tesla’s Gigafactory in Nevada is 0.1 terawatt-hours of battery output per year.

 

The interior of the 4680 EV cell from above. All images courtesy of Tesla.

 

Interior of a conventional EV cell.

 

 

The new battery is the 4680, so named because those are its dimensions—46 mm. wide and 80 mm. tall. That’s more than double the width and 10 mm. taller than the current 2170s in Tesla vehicles. The increased volume adds power, but the revolutionary difference is the interior core of the battery. A standard EV battery has a 3-meter long sheet with anode material coating on one side and cathode on the other, tightly wound and inserted in a protective canister. Tabs attached to the anode and cathode layers provide connective poles for wiring.

 

The 4680 has replaced the tightly wound sheets with a laser-scribed “shingled spiral.” It has no tabs and many more points of conductivity. Electrons flowing in a conventional battery may have to travel much of the length of the sheets to complete connections in the conventional cell, but in the 4680, the farthest they need to travel would be the 80 mm. height of the canister. This efficiency not only seriously cuts down on the heat produced, but it also creates more power per cell. The 4680 will provide five times more energy capacity, will be six times more powerful, and will increase the range for Tesla’s vehicles by 16%.

 

A new chassis design for structural batteries.

 

The new batteries will be arranged in what Musk called a “structural battery pack.” Unlike current battery trays that are filled and then dropped into and bolted to the chassis, the bottom of the car’s interior body will be pressed in a single piece that includes the front and back of the chassis and a molded battery holder that’s an integral part of the design. For this, Tesla designed what Musk says is the largest casting machine on earth. They also needed to create a new alloy of aluminum for the pressings. This results in a 10% mass reduction, 370 fewer parts, and a “stiffer,” more manageable, safer car.

 

A LITHIUM MINE

 

Musk and Tesla’s vice president of powertrain and energy Drew Baglino, then explained that lithium isn’t a rare earth element. It’s abundant here in the United States and elsewhere, and mining can be safe. You can extract lithium using sodium chloride, or common table salt. Tesla has access to a 10,000-acre lot of “lithium-rich clay deposits” on the site where the company already has the Gigafactory. They intend to explore mining in the area.

 

 

Tesla also has a dry process for creating coatings on films, which can produce a 10X reduction of energy needed and a 10X reduction of factory floor space in the production of cathodes and anodes. They’re also working on a cheaper grade of silicon and ways to use nickel instead of cobalt in the cathodes of their batteries.

 

Musk said he wants to build a factory to produce the materials for cells in North America and that producing cathodes would put the company in the recycling part of it. Combining their research, he said they would be able to make cathodes 76% cheaper.

 

MANUFACTURING CIRCLE OF LIFE

 

Although many were disappointed that Battery Day didn’t include the unveiling of a battery with a lifetime of one million miles and 10 years, what was presented in the plans laid out for accommodating the new EV cells described a life cycle that enfolded materials, manufacture, and recycling. Not merely a million-mile cycle, something more perpetual.

 

Certainly, much of the plan is in very early stages. The battery production line is 12 to 18 months away from full production. The shovels haven’t been stepped into the ground at the lithium mining site, and a cathode production factory exists now only on paper. But one thing is almost imminent: The 4680 EV cell is close to production ready.

 



Michael Castelluccio has been the Technology Editor for Strategic Finance for 25 years. His SF Technotes blog is in its 22nd year. You can contact Mike at mcastelluccio@imanet.org.


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