When Chrysler unveiled its Halcyon Concept electric sedan on Tuesday, it noted that the vehicle “contains 800-volt lithium-sulfur batteries,” which it said have an estimated carbon footprint of about 60 percent less than today's best batteries.
The Lyten cells you “envision” use do not contain nickel, cobalt, or manganese among their metals. Instead, they use sulfur, which is lower on the atomic table than the metals used in lithium-ion cells today — which means the cells are more energy dense, meaning they weigh less for a given energy capacity. Sulfur is also the fifth most common element on Earth, being found in volcanic areas and near hot springs around the world, which may reduce the cost of raw materials.
Last May, the statement said, “Stellantis Ventures, Stellantis’ venture fund, announced an investment in Lyten to accelerate the commercialization of Lyten 3D Graphene applications for the mobility industry.” In other words, Stellantis has invested in a company that makes a key component of lithium sulfur cells. So it makes sense that they would show up in a pure electric car that looks far from being production-ready.
Unfortunately when Car and driver I reached out to Stellantis for more details, and the company declined to discuss the new cells. A Chrysler/Dodge spokesperson responded: “Thanks for reaching out, but at this time we are not providing additional details on future battery technology as envisioned for the Halcyon concept.”
Future cell?
Lithium-ion sulfur cells are being replaced by various mixtures of nickel, manganese, cobalt, and aluminum (collectively known as NMCA) found in most EV cells today. In theory, this results in a higher power density than current cells, which translates to greater EV range in less volume and less mass. But, as of today, there is not a single vehicle on the road powered by this technology.
However, efforts to reduce or eliminate the use of rare and expensive metals have increased, as electric vehicle makers look beyond today's NMCA and the less expensive but less energy-dense iron phosphate (LFP) chemistry. The goal is to use other elements – especially those in abundance – that have the right properties to carry energy.
To truly evaluate the place of lithium sulfur cells in electric vehicles, Car and driver I reached out to Harish Kamath, director of energy storage at the Electric Power Research Institute, known as EPRI.
We asked Kamath whether lithium-sulfur batteries represent a reliable alternative to today's lithium-ion cells. “They've been recognized as such for 30 years, but it will likely take years of sustained work on the technology for them to get access to this technology,” he said. [create] Successful products, scalable manufacturing and marketing.”
Even with all these challenges, “there is no guarantee that commercial lithium sulfur products will be cost-competitive with lithium ion,” Kamath cautioned. “Comprehensive commercialization will require us to once again address the big questions about the fire and explosion risks of a new technology that has important safety differences from lithium-ion.”
He continued: “Transferring any battery technology from the laboratory to the field is no joke: it requires a lot of capital investment and the means to design, build, qualify, and scale up successively the cells, then the batteries, then the systems.” I continued. “This takes years. Even mature, knowledgeable and well-capitalized companies rarely stick to their own timelines.”
However, “the companies developing batteries today are huge operations backed by huge investments and the willingness to take the time needed to get there,” Kamath said. “These large-scale efforts by Sony and Panasonic in the 1980s led to the successful commercialization of lithium-ion batteries. These efforts are now being applied to solid-state batteries, silicon anodes, and more.”
But Kamath cautioned that lithium sulfur is not an easy substitute for lithium ion. He highlighted four important points that he believes developers should pay close attention to:
- Cell voltage is half that of a typical lithium-ion cell when fully charged (2.1 V/cell vs. 4.2 V/cell). This requires more cells per battery, which may reduce energy density.
- The life cycle of lithium sulfur has been very bad for many times. Many researchers say they have addressed these issues, but we have yet to see data showing that these cells perform as well as lithium-ion.
- Unlike lithium-ion, lithium-sulfur exhibits side reactions that lead to inefficiency during charging, reducing charging efficiency and generating heat that must be handled carefully to maximize battery life.
- Lithium sulfur contains metallic lithium, so it requires different safety methods than lithium ion cells in all chemistry.
Not quite ready
In summary, lithium-sulfur battery chemistry remains under development. Like solid-state lithium-ion cells, the chemistry shows promise in theory, but has not yet advanced to the stage where it will soon be scaled up for mass production and use in electric vehicles. As Kamath points out, battery development takes a very long time.
This means that Chrysler's late-2020 EVs, whatever they may be, are more likely to be powered by some type of lithium-ion cell found today than by lithium-sulfur cells.
The author wrote occasional analyzes of the world of electric vehicles for the Electric Power Research Institute (EPRI), and in this way came into contact with the director of energy storage, Harish Kamath, mentioned in the article above.
Edited by John Voelker Green car reports For nine years, he published more than 12,000 articles on hybrid cars, electric cars, other low- and zero-emission vehicles, and the energy ecosystem surrounding them. He now covers advanced automotive technologies and energy policy as a reporter and analyst. His work has appeared in print, electronic and radio media including Wired, Popular Science, Technical Review, IEEE Spectrum, and “All Things Considered” on NPR. He divides his time between the Catskill Mountains and New York City and still hopes to one day become a global man of mystery.
