The crowded field of next-generation EV batteries is getting more crowded by the minute. New solid-state technology has been catching much of the attention, but lithium-sulfur formulas have also attracted innovators and investors. Sulfur is an abundant, non-toxic, low cost material that could bust the EV market wide open, if only researchers could solve some pesky chemical and mechanical degradation problems.
The Long Road To Lithium-Sulfur EV Batteries
Lithium-sulfur EV batteries crossed the CleanTechnica radar regularly during the Obama administration. Back in 2015, for example, we noted that the lithium-sulfur combo could help push down the cost of electric vehicles by scratching conventional lithium-ion technology off the board.
“Until now, lithium-ion batteries have been the gold standard for EV batteries, but they are still fairly heavy and costly affairs, and their limitations are the key reason why EVs are still beyond the reach of many auto buyers,” we noted.
The cost of lithium-ion technology has been dropping since then, and lower-cost EVs are emerging in the market. Still, the car buying public is being squeezed financially from all directions. Pushing the price of an EV down as far as possible would help make zero emission mobility an economical choice as well as an environmental one.
That’s all well and good, but lithium-sulfur battery developers have a lot on their plates. In terms of chemical issues, earlier iterations of the technology tended to degrade after just a few charging cycles. Mechanical degradation also occurs as the battery shrinks and swells.
“The result is that particles of sulfur drift around without an electrical function, cutting down on efficiency and contributing to the delinquency problem,” we noted.
Lyten Is Shipping New Lithium-Sulfur EV Batteries
One of the startups tackling the lithium-sulfur challenge is the California firm Lyten, and it has been making some big moves in recent months. In the latest news, earlier this week the company announced that it is shipping A samples of its new lithium-sulfur pouch cells to automakers in the US and EU for evaluation.
Shipping A samples for evaluation is a long way from commercial-level production. Lyten is currently producing its A samples at a pilot-scale line that began operating in last year. However, it is still a significant milestone for new EV batteries. As described by Lyten, the sample shipment “starts the clock” on a series of steps leading to the mass market. The pilot line also deploys standard lithium-ion manufacturing equipment, to demonstrate the potential for rapid scale-up.
“Lyten manufactures lithium-sulfur cells in both pouch and cylindrical formats (2170 and 18650) and is currently shipping the 6.5 Ah pouch cell format for customer evaluation,” the company explained in a press release dated May 8. Lyten also expects to ship A samples of the cylindrical cells later this year.
Cleaning Up The EV Battery Supply Chain
Considering that lithium-ion technology was already maturing while researchers were just getting started on lithium-sulfur, it’s fair to ask why bother trying to catch up. Lyten brings up four good reasons.
First is energy density. Lyten claims that the lithium-sulfur formula can deliver twice the energy density of lithium-ion batteries in the form of nickel-manganese-cobalt technology. In terms of EV applications, that means more driving range or the same range packed into a smaller, lighter space.
Second is cost. Lyten makes its cathodes with sulfur and a proprietary from of graphene, eliminating the use of the more expensive materials cobalt and manganese, as well as nickel. The lithium-metal composite anode also eliminates graphite from the EV battery picture.
Third is carbon footprint. Lyten calculates that eliminating cobalt and other critical materials translates into a sharp reduction in energy associated with battery manufacturing. The company projects a 65% lower carbon footprint for its batteries.
The fourth factor is supply chain reliability and national security. Lyten states that its EV batteries can be sourced entirely within the US and EU.
Who Wants New Lithium-Sulfur Batteries?
As for who will be the early adopters of those new EV batteries, Lyten name-droppped Stellantis in its press release among a potential delivery target of more than 20 yet-to-be-named customers. The company notes that earlier this year, Chrysler featured the new Li-S EV batteries in its newly unveiled, futuristic Halcyon concept car.
Lyten also mentioned defense applications, where that thing about domestic supply chain accessibility has already come into play.
On January 30, Lyten let word drop that it nailed down a grant of $4 million from the US Department of Energy, following passage of a new law that restricts the ability of the US Department of Defense from buying batteries from Chinese firms. The restrictions go into effect in 2027.
“The DoE grant awards for lithium-sulfur follow the passage of National Defense Authorization Act, signed into law last month with bi-partisan support, which will prohibit the U.S. Defense Department from buying batteries produced by China’s largest manufacturers starting in October 2027,” Lyten explained.
Under the grant, Lyten will be working with Stanford University, the University of Texas-Austin, and the firm Arcadium Lithium (created by a merger between Livent and Allkem), with the aim of accelerating the manufacture of lithium-sulfur batteries.
Don’t get too excited about that national defense angle just yet, at least as far as EV batteries go. The Pentagon routinely uses rechargeable batteries for electronic devices, but it has been extremely cautious about electrifying its gigantic fleet of ground vehicles.
As of 2015, the picture looked particularly gloomy in regards to conventional lithium-ion technology. On the plus side, the Army has been poking around in the sulfur field for an alternative solution. Back in 2015, for example, the Army Research Laboratory participated in an assessment of strategies to prevent degradation of lithium-metal anodes in lithium-sulfur batteries. Another development cropped up in 2017, when the Army Research Laboratory teamed up with the University of Oxford and the University of Michigan to explore the use of solid electrolytes for lithium-sulfur EV batteries.
Among more recent developments, in 2020 Army researchers helped produce a multi-institution study of lithium-sulfur batteries, focusing on a new performance-enhancing electrolyte.
Researchers from the University of Michigan have also been deploying recycled Kevlar fibers to extend the lifespan of lithium-sulfur batteries and keep costs down, in a project funded by the Defense Department along with the National Science Foundation.
Keep your eyes open for more news about EV batteries from the Defense Department. Things have been crawling along at a sleepy pace, but some new activity in the area of electric emergency response vehicles could indicate that the pace is ready to pick up.