U.S. startup bets on lithium-sulfur to challenge China's EV battery dominance

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6 days ago

SAN JOSE, Calif. — A new generation of battery technologies could loosen China's grip on the EV market, driven by breakthroughs that address long-standing technical hurdles. Chief among them: lithium-sulfur chemistries built on a domestic U.S. supply chain.
Lyten, a Silicon Valley startup backed by Stellantis, plans to commercialize small Li-S batteries for military drones later this year. Larger versions for electric vehicles are expected before the end of the decade, officials at the San Jose company said.
To be sure, lithium-sulfur batteries still face steep hurdles, including limited cycle life, the number of times they can be charged before performance drops. But after five years of development, Lyten sees a clear path to commercial success.
'This is no longer a moonshot,' Keith Norman, chief marketing and sustainability officer at Lyten, told Automotive News. 'I'm not saying that everything is done and tidied up and it's ready for perfect scale today. But this is a landing mission.'
Last year, Lyten acquired a lithium-metal battery plant near its Bay Area headquarters, which it plans to convert for Li-S production. It also bought a lithium ion plant in Poland that makes batteries for energy storage, with plans to add Li-S production there as well.
While Lyten's Li-S batteries are debuting in drones, broader applications are expected to follow. Potential markets include electronics, satellites, e-bikes, energy storage and eventually EVs.
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Sulfur-based batteries don't use nickel, cobalt, manganese, or graphite like conventional lithium ion batteries. China dominates the global supply and refining of those materials, as well as the manufacturing of lithium ion cells themselves.
While most lithium is mined and processed overseas, efforts are underway to build a U.S. supply chain. Lyten sources its lithium metal domestically, sidestepping Trump-era tariffs on battery components and broader geopolitical trade risks.
'You have something that gets you out of geopolitics with batteries and you can also produce it on every continent,' said Celina Mikolajczak, Lyten's outgoing chief battery officer. The company announced her departure on July 22.
Sulfur is a U.S.-made alternative and a lighter material
As a byproduct of oil refining, sulfur is cheap and abundant in the U.S. but hasn't drawn much attention as a battery material given the dominance of older chemistries.
'Most of the R&D activities from the big cell makers have been entirely focused on conventional lithium ion because that's what they make and they've had commercial success with it,' Mikolajczak said. 'So, they're just going to keep making it better.'
But 40 years after the first commercially viable lithium ion battery, automakers, military drone manufacturers, and energy-storage firms are searching for U.S.-made alternatives. Sulfur is lighter than heavy metals and potentially offers higher energy density.
Stellantis announced an investment in Lyten two years ago 'to develop applications for advanced lithium-sulfur EV batteries,' without disclosing the amount. In December, Stellantis said it's partnering with another Li-S startup, Zeta Energy of Houston.
Sulfur-based batteries are also more environmentally friendly than chemistries that rely on mined heavy metals.
The main weakness of a Li-S battery is a reaction called polysulfide shuttle. Sulfur from the positively charged cathode dissolves into liquid electrolyte, forming polysulfides that migrate to the anode. If not contained, they trigger reactions that reduce cycle life.
'With these cells, cycle life is the hardest thing,' Mikolajczak said. 'This is the thing we are pushing on and pushing on and continue to iterate on. And we're making really good progress.'
Lyten mitigates polysulfide shuttle with its proprietary 3D Graphene material, which traps sulfur and prevents it from dissolving into the electrolyte. It also manufactures its own lithium-metal anodes, engineered to reduce unwanted reactions and extend cycle life.
Challenges related to cycle life of sulfur batteries
University of Texas at Austin professor Arumugam Manthiram, an early researcher into sulfur-based batteries, told Automotive News that Li-S batteries aren't ready for most applications.
In addition to the polysulfide shuttle, Li-S batteries suffer from sulfur's poor conductivity, requiring added carbon and liquid electrolyte — 'dead weight' that lowers energy density, Manthiram said.
'Right now, because of these problems, we do not have acceptable cycle life so that we can use these in an electric vehicle,' said Manthiram, who has worked with Lyten.
'I don't think anyone has more than 250 charge-discharge cycles' in Li-S batteries. Manthiram said. The minimum for EVs and other heavy uses, such as energy storage, is a thousand cycles while retaining 80 percent of capacity, he added.
Another approach for sulfur-based batteries is using solid electrolytes, something that's already in development for so-called solid state lithium ion batteries, Manthiram said. Either way, Li-S batteries are probably five to 10 years away for EVs, he added.
Lyten's use of a liquid electrolyte makes it easier to convert existing battery plants with similar manufacturing processes, which the company could acquire as opportunities arise, Mikolajczak said. Lyten is also building its own $1 billion cell factory in Nevada.
'One of the beauties of this technology is that it can slot into an existing facility,' she said. 'Solid-state can't.'
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