Simplifying the production of lithium-ion batteries | MIT News

In battery innovation, much attention is paid to potential new chemistries and materials. The importance of production processes for reducing costs is often overlooked.

Now, MIT spinout 24M Technologies has simplified lithium-ion battery production with a new design that requires fewer materials and fewer steps to manufacture each cell. The company says the design, which it calls “SemiSolid” because of its use of sticky electrodes, cuts production costs by up to 40 percent. The approach also improves the batteries’ energy density, safety and recyclability.

Judging by the industry interest, 24M is on the right track. Since 24M left stealth mode in 2015, 24M has licensed its technology to multinational companies such as Volkswagen, Fujifilm, Lucas TVS, Axxiva and Freyr. These last three companies plan to build gigafactories (factories with annual production capacity in the gigawatt range) based on 24M’s technology in India, China, Norway and the United States.

“The SemiSolid platform has been proven on the scale of hundreds of megawatts being produced for residential energy storage systems. Now we want to prove it at gigawatt scale,” says 24M CEO Naoki Ota, whose team includes 24M co-founder, chief scientist and MIT professor Yet-Ming Chiang.

Building large-scale production lines is only the first phase of 24M’s plan. Another important benefit of the battery design is that it can work with different combinations of lithium-ion chemistries. This means that 24M’s partners can later integrate higher-performance materials without significantly changing the manufacturing processes.

The kind of rapid, large-scale production of next-generation batteries that 24M hopes to enable could have dramatic implications for battery adoption across society – from the cost and performance of electric cars to the ability of renewable energy to replace fossil fuels to replace fuels.

“It’s a platform technology,” says Ota. “We are not just a low-cost and highly reliable provider. That’s who we are today, but we can also be competitive with next-gen chemistry. We can use any chemistry on the market without customers having to change their supply chains. Other startups try to address this problem tomorrow, not today. Our technology can solve the problem today and tomorrow.”

A simplified design

Chiang, who is the Kyocera Professor of Materials Science and Engineering at MIT, got his first taste of large-scale battery production after co-founding another battery company, A123 Systems, in 2001. As this company prepared to go public in the late 2000s, Chiang began to wonder if he could design a simpler battery to manufacture.

“I got this window on what the battery manufacturing was like, and what struck me was that even though we managed to do it, it was an incredibly complicated manufacturing process,” says Chiang. “It dates back to magnetic tape manufacturing adapted to batteries in the late 1980s.”

In his lab at MIT, where he has been a professor since 1985, Chiang started from scratch with a new type of device he called a “semi-solid flow battery” that pumps liquids to and from tanks using particle-based electrodes to store a charge.

In 2010, Chiang partnered with W. Craig Carter, the POSCO Professor of Materials Science and Engineering at MIT, and the two professors mentored a student, Mihai Duduta ’11, who was researching flow batteries for his bachelor’s thesis. Within a month, Duduta had developed a prototype in Chiang’s lab and 24M was born. (Duduta was the company’s first employee.)

But even as 24M worked with MIT’s Technology Licensing Office (TLO) to commercialize the research being conducted in Chiang’s lab, company collaborators, including Duduta, began rethinking the flow battery concept. An internal cost analysis by Carter, who worked as a consultant for 24M for several years, finally caused the researchers to change direction.

This left the company with a lot of sticky sludge to make up the electrodes in their flow batteries. A few weeks after Carter’s cost analysis, Duduta, then a senior research scientist at 24M, decided to use the mud to hand-assemble batteries by mixing the sticky electrodes directly into the electrolyte. The idea caught on.

The main components of batteries are the positively and negatively charged electrodes and the electrolyte material that allows ions to flow between them. Traditional lithium-ion batteries use solid electrodes that are separated from the electrolyte by layers of inert plastic and metal that hold the electrodes in place.

Removing the inert materials of traditional batteries and embracing the sticky electrode mix gives the 24M’s design a number of advantages.

On the one hand, the energy-intensive process of drying and solidifying the electrodes in traditional lithium-ion production is no longer necessary. The company says it also reduces the need for more than 80 percent of the inactive materials in conventional batteries, including expensive materials like copper and aluminum. The design also uses no binders and features extra-thick electrodes, improving the batteries’ energy density.

“When you start a business, it’s wise to review all your assumptions and ask yourself how best to achieve your goals, which in our case was simply manufactured, inexpensive batteries,” says Chiang. “We decided that our real value was in making a lithium-ion suspension that was electrochemically active from the start, with electrolyte in it, and you just use the electrolyte as the processing solvent.”

In 2017, 24M participated in the MIT Industrial Liaison Program’s STEX25 Startup Accelerator, where Chiang and his collaborators forged important industry connections that would help secure early partnerships. 24M has also worked with MIT researchers on projects funded by the Department of Energy.

Enabling the battery revolution

Most of 24M’s partners have the fast-growing electric vehicle (EV) market in mind for their batteries, and the founders believe their technology will accelerate EV adoption. (Battery costs account for 30 to 40 percent of the price of electric vehicles, according to the Institute for Energy Research).

“Lithium-ion batteries have improved tremendously over the years, but even Elon Musk says we need a breakthrough technology,” says Ota, referring to the CEO of electric vehicle maker Tesla. “To spread electric vehicles further, we need a breakthrough in production costs; We can’t just rely on cost reduction through scaling because we already make a lot of batteries today.”

24M is also working to test new battery chemistries that its partners could quickly integrate into their gigafactories. In January of this year, 24M received a grant from the Department of Energy’s ARPA-E program to develop and scale a high-energy-density battery using a lithium-metal anode and semi-solid cathode for use in electric aviation.

This project is one of many around the world aiming to validate new lithium-ion battery chemistries that could enable a long-awaited battery revolution. As 24M continues to foster the creation of large, global production lines, the team believes they are well positioned to transform laboratory innovations into ubiquitous, world-changing products.

“This technology is a platform and our vision is to be like Google’s Android [operating system], where other people can build things on our platform,” says Ota. “But we want to do it with hardware. That’s why we license the technology. Our partners can use the same production lines to take advantage of new chemistries and approaches. This platform gives everyone more opportunities.”


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