MIT's Star Prof. Don Sadoway on Innovations in Energy Storage

Jul 27, 2023

Don Sadoway, MIT Professor of Materials Chemistry, is one of the school's most popular professors and sought-after speakers. He spoke at the Palo Alto Research Center on March 8 in an event sponsored by the MIT Club of Northern California.

If you have a chance to take Sadoway's class or to hear him speak -- do it. He's one of the more entertaining and informative teachers you'll encounter, even if he's lecturing on solid-state chemistry. The talk in this video is close to the lecture he gave at PARC.

Sadoway's research ranges from metals production and portable energy storage devices to his "liquid battery," which has applications in grid-level storage for renewable energy applications.

Sadoway discussed two technical topics -- liquid metal batteries for large-scale energy storage and non lithium-ion batteries for automotive applications. He also touched on teaching, learning, music, and art.

The professor spoke about how rechargeables have improved as we progressed from lead acid at 35 Wh/kg to Li-ion at 150 Wh/kg (versus gasoline at 12,000 Wh/kg). But Sadoway doesn't think that Li-ion batteries have a future in grid-scale or transportation applications. We need to change chemistries and that takes radical innovation, according to Sadoway, in order to make solar and wind power more dispatchable. In this case, we need to make a battery that can handle high current.

Lithium-ion batteries in phones and cars have to be ultra-safe. Cell phones "need to be idiot-proof, largely because they are in the hands of idiots," and batteries in cars need to be able to withstand a crash. Stationary batteries for bulk storage are not held to those same requirements, which allows more freedom in choice of chemistry but the application requires a very low price point -- and Sadoway insists that you have to think about price point at the beginning of the product design process.

Automotive traction for an all-electric car has a target cost of $100 to $200 per kWh, and stationary storage needs to be in the vicinity of $50 per kWh, according to Sadoway.

Sadoway also weighed in on the woeful state of energy research in the U.S., saying, "We need to accelerate the rate of discovery. We can make batteries two or three times better if we're willing to make the investment." He said that energy research has fallen by a factor of six, while medical research has grown by a factor of four since the 1970s. He said that the U.S. energy industry spends 0.25 percent of revenues on R&D, while the pharmaceuticals industry spends 18 percent and semiconductor firms spend 16 percent. Even the automotive industry spends 3 percent of its revenues on R&D.

Getting back to battery research, Sadoway recommended that researchers "confine their search to earth-abundant elements. The only way to make something dirt cheap is to make it out of dirt -- American dirt."

A colossal yet cheap battery

Sadoway challenged the research community to invent a colossal yet cheap battery. He directed researchers to look at the economy of scale of modern electrometallurgy and the aluminum smelter, which handles the holy grail of batteries -- achieving a high current while maintaining massive scale.

Why is an aluminum cell not a battery? You have to produce liquid metals at both electrodes.

Making metal at the cathode is trivial, but making metal at the anode is not so trivial. So Sadoway went back to the Periodic Table and used magnesium to "intimidate" antimony into behaving like a non-metal. From there, using seed money from within MIT, Sadoway and his team invented the liquid metal battery or, more academically, a process called "Reversible Ambipolar Electrolysis."

The battery uses molten antimony and molten magnesium separated by an electrolyte. Sadoway claims that the all-liquid configuration is self-assembling and is expected to be scalable at low cost. Furthermore, this technology may have a shot at being cheaper than sodium sulfur (NaS) batteries.

The team has since received $7 million from ARPA-E and $4 million from Total and has spun out a firm called the Liquid Metal Battery Company.

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On a completely different topic, here's Sadoway's Dinnertime Sampler playlist from 2002. The professor usually throws in some tunes to illustrate a point -- "Water Music" for aqueous chemistry, "The Twist" for DNA, etc.

Donald R. SadowayJohn F. Elliott Professor of Materials Chemistry, MacVicar Faculty Fellow