By the time the Swedish battery giant Northvolt declared bankruptcy last month, a well-funded U.S. startup, Lyten, had already swooped in to snatch up the company’s previously shuttered Bay Area factory. With China flooding the market with its cheap lithium-ion tech, Lyten is betting that creating a fully domestic battery supply chain will require alternate chemistries — like, say, lithium-sulfur, Lyten’s recipe of choice.
Lithium-sulfur has long been a promising contender, as in theory, these batteries can have a much higher energy density — the amount of energy that can be stored in a given space — than traditional lithium-ion. They also rely primarily on cheap, abundant, and easy to access materials. “We don’t use nickel, we don’t use manganese, we don’t use cobalt, we don’t use graphite,” Keith Norman, Lyten’s chief sustainability officer, told me — all markets where China plays a leading role. Scaling up standard lithium-ion battery production to meet forecasted global demand would require opening nearly 400 new mines by 2035, according to Benchmark Mineral Intelligence. “We believe if you could snap your fingers and change that to lithium-sulfur, that mining requirement will be reduced somewhere between 80% and 90%,” Norman said.
Lyten’s customers, Norman said, want these batteries as soon as possible, and acquiring Northvolt’s old 200-megawatt plant will allow the company to begin commercial production there next year. Lyten also recently announced plans for a Reno-based gigafactory, which is scheduled to come online in 2027. Zeta Energy, a Houston-based lithium-sulfur startup, also aims to commercialize in 2025, and is set to announce the opening of its 100-megawatt plant in the coming weeks.
While both companies have dreams of enabling more efficient, lightweight, and cost-effective electric vehicles and energy storage systems, there are reasons why lithium-sulfur has yet to be commercialized.
For one, sulfur is generally a poor conductor of lithium ions, and therefore requires extra conductive material to compensate, increasing the battery’s weight. Lithium-sulfur batteries also have notoriously short cycle lives due to the “polysulfide shuttle effect,” which causes the sulfur in the cathode to dissolve in the liquid electrolyte, damaging the anode and — you guessed it — decreasing the battery’s capacity and cycle life.
“It could be solved,” Arumugam Manthiram, an engineering professor and battery researcher at the University of Texas at Austin, told me. After being involved in the initial lithium-ion battery breakthroughs of the 1980s, Manthiram said he’s seen traditional battery tech continue to improve year after year. He thinks lithium-sulfur will follow the same trajectory, only quicker. “Can it be solved in five years, 10 years? I’m optimistic.” he told me. He’s currently working with Lyten on a Department of Energy-funded grant to accelerate the commercialization of lithium-sulfur batteries for use in EVs.
Zeta thinks it’s already found the ticket, though. It claims to offer three times the energy density of traditional lithium-ion at less than half the price. While Melissa Schilling, Zeta’s head of strategic marketing and innovation, couldn’t reveal much about Zeta’s proprietary cathode, she did tell me that it’s made of a sulfur-carbon polymer that eliminates the dreaded polysulfide shuttle effect (a claim that’s been externally verified) and allows for greater electrical conductivity. The company’s lithium-metal anode is made of carbon nanotubes, a.k.a. tiny cylinders composed of carbon atoms. The nanotubes help improve the anode’s stability, thus increasing energy density compared with traditional graphite anodes while also preventing the formation of dendrites, tiny projections on the anode that can cause the battery to break down.
Zeta’s batteries can go through about eight times more charge/discharge cycles than traditional lithium-sulfur batteries, according to the company’s figures and Manthiram’s estimation of a typical life cycle. Optimizing these batteries for EVs, though, will likely mean a much shorter cycle life, which may not be on par with what lithium-ion can do. Even so, Schilling told me, “what we’re going to beat lithium-ion on is density and cost.” The company has raised $30 million to date, and is in the midst of raising its Series B round. While Schilling couldn’t reveal the names of Zeta’s initial customers, she told me that the company is collaborating with a large automaker and heavy equipment manufacturer. Zeta has also received the same commercialization grant from the DOE as Lyten.
For its part, Lyten currently provides 25% greater energy density than top-of-the-line lithium-ion batteries, Norman told me. The company expects that soon, it will be able to offer twice the energy density at half the material cost. Lyten’s tech relies upon a so-called supermaterial, three-dimensional graphene, which it’s developing in-house. This gets combined with sulfur in the cathode to form a more conductive and stable composite material.
Norman said you can think of 3D graphene like a sponge with pore sizes “perfectly designed to hold sulfur atoms.” The graphene “gives [the sulfur] conductivity and gives it a rigid structure that doesn’t allow it to break down as easily,” he told me, meaning the battery is less likely to succumb to the polysulfide shuttle effect. Lyten’s anode is also made of energy dense lithium-metal.
Lyten hasn’t publicly revealed its battery’s cycle life, however, and in a follow-up email, Norman told me that when it comes to EV batteries, Lyten is “not yet at the cycle life we need,” though the company is “seeing 20-30% improvement in lithium-sulfur battery performance each year.” For customers using lithium-sulfur for earlier-stage applications such as drones, satellites, and two- and three-wheelers, Norman wrote that Lyten’s current cycle life “meets or very nearly meets their requirements.”
The company seems to have the money to work towards these improvements. Lyten achieved “unicorn” status last year, recording a valuation over $1 billion after closing a $200 million Series B round. It counts Stellantis and FedEx among its backers, and the Department of Defense is even funding a demonstration of Lyten’s battery tech aboard the International Space Station, where lithium-sulfur cells will be tested for use in everything from satellites to space suits.
Norman told me the company’s recent purchase of Northvolt’s old Bay Area facility represents an important step in Lyten’s path to scale. The California plant was originally designed to produce lithium-metal batteries for Cuberg, a startup Northvolt acquired in 2021 and closed down this summer. Like Lyten’s and Zeta’s, Cuberg’s batteries used a pure lithium-metal anode, while its cathode was the same old nickel-manganese-cobalt chemistry that conventional lithium-ion batteries use. With this kind of chemistry, Norman told me, it would be “very difficult to ever compete on costs.”
One of the main ways that Northvolt ultimately went wrong, Norman and Schilling agreed, is that it tried to scale standard lithium-ion tech too quickly in a price-sensitive environment. “They kind of went right to these 10, 20, 30 gigawatt-hour facilities,” Norman told me. “As they tried to scale those, they ran into a lot of manufacturing challenges and just the cost and time of trying to learn that on these huge facilities kind of bit them.” Schilling told me she thinks QuantumScape, a manufacturer of solid-state batteries for EVs, is running the same risk.
To compete with the low-cost Chinese batteries flooding the market, Norman told me domestic tech has to be demonstrably better — incremental improvements in efficiency, cost, or sustainability will not be enough. “Fundamentally, you’ve got to have a differentiated battery that customers are really dying to get their hands on,” Norman told me. But he knows that if Lyten successfully commercializes lithium-sulfur, other companies and countries will quickly get into the game.
After all, major battery giants such as LG, Samsung, SK, and Panasonic are well aware of what’s going on in the lithium-sulfur space, Manthiram told me, even if they’ve yet to make any noise about it. “They are quietly doing some work, R&D. They don’t hype it because they have a product already made,” Manthiram said, referring to the company’s widely available lithium-ion batteries. “They are also watching what academic labs are doing, what Lyten is doing, what others are doing.”
These behemoths are sure to pounce when and if the timing is right. Yet Lyten and Zeta still have the opportunity to pioneer a novel battery technology that can be fully made in America — something thus far unheard of in the battery universe.
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