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Unlocking Mass Production of Solid-State Batteries

Ilene Wolff
By Ilene Wolff Contributing Editor, SME Media

Battery production is a hot topic today, as is scaling up that production. Sakuu Corp., formerly KeraCel Inc., claims it has unlocked the secret to mass-produced, solid-state batteries (SSBs). The solution is additive manufacturing (AM). The San Jose, Calif., company is preparing to make its own batteries of ceramic and pure lithium and sell its AM technology later this year.

If true, the company has beat many other companies, including Toyota Motor Corp., in its quest to be first to make a scalable SSB. The technology is desirable due to its advantages over lithium-ion batteries, commercialized in the early 1990s. SSBs can withstand higher temperatures, charge faster and endure more charge/discharge cycles before degrading. They’re also more energy dense, allowing for volume and weight reduction. Eliminating flammable liquid electrolytes means safety electronics can be eliminated from the battery pack, too. SSBs have been used for years in small devices like pacemakers, wearables and radio-frequency identification.

Properties such as higher energy density, light weight, faster charging and increased safety are especially critical for electric vehicles. In fact, the future of electric vehicles may rest on the ability to mass produce SSBs, some say. “A big leap is needed to increase the distances these batteries can power cars,” wrote Emily Pickrell, University of Houston (UH) Energy Scholar, on the UH Energy Fellows Forbes Blog in June. “In concrete terms, this has limited how far EV cars can drive before they need to be recharged.”

SSBs are so vital to the future of EVs that automakers are investing in battery development companies, according to published reports. BMW and Ford have invested in Solid Power, which has set early 2022 for piloting production of EV batteries. Volkswagen has invested in QuantumScape, which aims to offer commercial SSBs by 2024. Toyota plans to use its first SSB for an EV by 2030. Sakuu is partnering with Honda affiliate Musashi Seimitsu, a Japanese automotive parts supplier to major OEMs, according to a press release.

Robert Bagheri, founder, CEO and chairman of Sakuu, said in an interview his company succeeded over competitors because 3D printing is the only way to make the ceramic layer in a battery thin enough for optimal performance. His company’s technology uses powder-based binder jetting to produce batteries in a green state. The pieces are then finished in a sintering furnace.

3D Printing is the Only Way

“They (competitors) try to build this the old way, the roll-to-roll method, but the ceramic is very brittle,” said Bagheri. “It cannot work in a roll-to-roll environment. It has to be very thin, like under 50 µm thin or under 30 µm thin. The only way to do that is with 3D printing. That’s why no SSB company yet has been able to scale.”

Sakuu printers can print different materials in a single layer, something Bagheri said is a first. “We can bring metal, ceramic (and) polymer all within the same layer, with the same tooling,” he said. “It’s got a lot of built-in intelligence that allows us to do inline QA at every layer.”

He estimates one battery cell takes 30 seconds or less to print, and that the 8,000 cells in a 75-kW battery pack would take six hours, maximum. Bagheri, an electrical engineer with experience in the semiconductor industry, said his largest run as of mid-July was 250 cells in a month on Sakuu’s development machine. He hadn’t done a production run yet on the Sakuu 1000, the model that’s supposed to be available in the fourth quarter of 2021.

Beyond energy storage, Sakuu says its multiple-material, single-layer printing technology opens 3D printing to making sensors and electric motors for many applications.

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