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University of Michigan uses recycled Kevlar fiber to solve lithium-sulfur battery life cycle issues
The University of Michigan Chemical Sciences and Engineering team, led by Professor Nicholas Kotov, has developed a “new biologically inspired battery membrane” with recycled Kevlar fibers that could quintuple electric vehicle ranges and have a lifespan of 1,000 cycles.
The Ann Arbor, Michigan research facility is one of the best in the world, and Kotov, whose research focuses on the development of biomimetic nanocomposites, the self-assembly of nanoparticles, and chiral nanostructures, has worked to change the narrative on lithium-sulfur cells. “There are a number of reports claiming several hundred cycles for lithium-sulfur batteries, but it is achieved at the expense of other parameters—capacity, charging rate, resilience, and safety,” Kotov said in a press release from the University. “The challenge nowadays is to make a battery that increases the cycling rate from the former 10 cycles to hundreds of cycles and satisfies multiple other requirements including cost.”
Lithium-sulfur batteries can enable five times the capacity of standard lithium-ion cells, which are used in electric vehicles. However, as Professor Kotov mentioned in his quote, the lifespan is significantly decreased due to chemical reactions between molecules. The most common reason for reduced life cycles in lithium-sulfur batteries is dendrites, which are appendages that are designed to receive communications from other cells. These can pierce the membrane of cells, reducing the life span and thus the life cycle of a battery cell.
Another problem is polysulfides, or small molecules of lithium and sulfur, can form and flow to the lithium. They bond and cause blockages, reducing the effectiveness of the membrane. “The membrane is needed to allow lithium ions to flow from the lithium to the sulfur and back—and to block the lithium and sulfur particles, known as lithium polysulfides.”
However, Kevlar, the same material used in bulletproof vests, can stop dendrites from penetrating the membrane using dense aramid fibers found in the material. The cells that Kotov and his team developed use recycled Kevlar fibers. The Kevlar “can enable lithium-sulfur batteries to overcome their Achilles heel of cycle life,” caused by the two previously mentioned reactions between molecules.
An example of the Kevlar system is shown in the images below, as the typical Celgard membrane on the left allows lithium polysulfides to flow through. The Kevlar membrane (right) blocked the polysulfides from traveling through.
“Just half an hour on, the Celgard membrane (left) leaks lithium polysulfides. However, the U-M membrane (right) completely blocks the lithium polysulfides 96 hours later. Image credit: Ahmet Emre, Kotov Lab.” Credit: University of Michigan
“Achieving record levels for multiple parameters for multiple materials properties is what is needed now for car batteries,” Kotov stated. Kotov added that the design of the lithium-sulfur batteries is “nearly perfect” due to its capacity and efficiency reaching theoretical limits. It can also behave more resiliently than lithium-ion cells in warm and cold weather climates, which both have effects on range and efficiency. However, fast charging could reduce the number of lifespans, Kotov added.
Lithium-sulfur batteries could be a good alternative as sulfur is more readily available and abundant than cobalt, which is controversial due to its mining practices. However, automakers like Tesla are reducing cobalt in their batteries vying for other metals, like nickel, instead. Sulfur’s low lifespan and instability, as it changes in size by 78 percent during charging, reduced the possibility of automakers using it in the past, The Independent reported.
The research was funded by the National Science Foundation and the Department of Defense.
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Tesla has secured regulatory approval for its Full Self-Driving (Supervised) system in Denmark, marking a significant step in the technology’s expansion across Europe.
Announced on June 9, the approval positions Denmark as the fourth European country to greenlight FSD Supervised, following the Netherlands, Lithuania, and Estonia.
Rollout to Danish vehicle owners is expected to begin soon, the company said.
The Danish Road Traffic Authority granted provisional approval after reviewing the original type approval issued by the Dutch vehicle authority (RDW) on April 10, 2026.
FSD Supervised now approved in Denmark 🇩🇰
Rollout will begin soon pic.twitter.com/Xpxwcme10k
— Tesla Europe, Middle East & Africa (@teslaeurope) June 9, 2026
This national recognition approach allows individual countries to bypass slower EU-wide harmonization processes, accelerating deployment. Lithuania activated the system on May 20, with Estonia following on May 29, demonstrating a rapid domino effect across the region.
FSD Supervised enables advanced driver assistance capabilities, including automatic steering, acceleration, braking, lane changes, and navigation through complex urban and rural environments. The system is designed for supervised use, as its name states, meaning drivers must remain attentive and ready to intervene at all times.
It adapts to diverse conditions, such as rain, night driving, and varied road types common in Denmark, but it is important to note that the tech is not fully autonomous.
Following a launch in Europe just a few months ago, with its first approval coming in the Netherlands, Tesla is just now highlighting the successful start.
Early data from the Netherlands highlights strong safety performance. Between April 10 and June 5, vehicles using FSD Supervised recorded 3.5 times fewer collisions than manual driving overall, with zero crashes reported on highways across more than 16.6 million kilometers driven.
These results underscore the potential of the technology to enhance road safety when properly supervised.
Tesla’s European push builds on its global footprint, now reaching 12 countries with FSD Supervised availability. The software receives continuous over-the-air updates, improving performance based on real-world data from millions of miles.
In Denmark, owners with compatible hardware—particularly newer vehicles equipped with Hardware 4 (HW4)—are anticipated to gain access first, though exact timelines and eligibility details will be confirmed during rollout.
This approval reflects growing regulatory confidence in supervised autonomy across Europe. As more nations recognize the Dutch certification, Tesla continues to demonstrate how its AI-driven approach can navigate real-world driving scenarios effectively. Denmark’s addition strengthens Tesla’s position in the region, paving the way for broader adoption on a continent that his been surprisingly slow to adopt the technology.
With FSD Supervised now approved in four European markets in just two months, the technology is steadily advancing toward wider availability. Tesla aims to refine the system further through ongoing data collection and software iterations, supporting its vision for safer and more efficient transportation.
Tesla has apparently revised the policy it previously had listed for Full Self-Driving transfers on the newest All-Wheel-Drive Cybertruck that the company had sold for a steal price of just $59,000 earlier this year.
After initially stating that customers who bought the pickup would be able to transfer FSD purchases, Tesla recently changed the language in those terms and conditions to reflect that this would no longer be the case.
Tesla launches new Cybertruck trim with more features than ever for a low price
The adjustment in terminology has caused a handful of orderers to cancel their reservations due to the loss of FSD transfer:
Just cancelled my 59k CT order today. My screenshot from that day of order (feb 20th) clearly shows that it would be eligible.
Terms were retroactively modified. Our 2020 Y and 2023 S are just fine for now. pic.twitter.com/D9PFnId1B4
— Ryan Scanlan 👥 (@Xenius) June 8, 2026
Tesla said orders for the new Cybertruck AWD must be placed by March 31, 2026, to qualify for the FSD transfer. The language in the document from earlier this year explicitly states that they “may qualify” for the transfer program, but the date of March 31 is explicitly mentioned.
Additionally, Tesla Delivery Advisors reached out to some orderers of the AWD Cybertruck, who were told there was “an update to the eligibility of the Full Self-Driving (Supervised) transfer.” Tesla stated they could:
- proceed without the transfer,
- upgrade to a Premium or Cyberbeast trim and request an FSD Transfer
- cancel the order and be refunded the $250 order fee.
Tesla turning around and changing these terms will undoubtedly result in a handful of cancellations on the part of those who have placed an order for this truck. They could pay $99 per month for an FSD subscription, which is now the only option available, but having purchased the suite outright on another vehicle and being told the transfer policy would be upheld, only to have it cancelled, is a tough pill to swallow.
These moves were also made by Tesla just before deliveries were set to begin on the Cybertruck AWD configuration. Reservation holders have started receiving VINs for their trucks, and Tesla is preparing to hand over the first units.
It’s a disappointing move from Tesla that will undoubtedly make some of its fans who have bought the truck frustrated.
In the world of autonomous ride-hailing, there are only a handful of names. Among those few companies lies a strategy play by each to keep the opposition on their toes. Tesla, on the other hand, already tipped its hand at where it is headed next.
Tesla has signaled its next major push in the autonomous ride-hailing market by filing for an Autonomous Vehicle Network Company permit in Nevada (Docket 26-05015). Through Tesla Robotaxi, LLC, the company seeks approval to operate up to 5,000 robotaxis in Clark County, including high-traffic areas like Las Vegas and Henderson airports, within the first 12 months of launch.
This filing builds on Tesla’s earlier testing approvals from the Nevada DMV in September 2025 and preparations such as maintenance hubs in the Las Vegas area. Nevada represents a strategic expansion into a major tourist destination, where high visitor volumes could drive strong utilization and showcase the reliability of unsupervised autonomy to a broad audience.
We’d have to assume this means Tesla is targeting Las Vegas, and it’s a great move from a business perspective.
Vegas is such a melting pot of people from all around the country and the world. It will expose people from all corners of the globe to Tesla’s autonomy capabilities https://t.co/Qz3fQmhULF pic.twitter.com/Du5pj2RyWC
— TESLARATI (@Teslarati) June 6, 2026
Approval would mark a significant step toward commercial operations in a new state, following progress in Texas.
Tesla’s shareholder decks and earnings calls have clearly outlined these ambitions. In the Q4 2025 shareholder deck, the company listed planned Robotaxi coverage for the first half of 2026, explicitly naming Las Vegas alongside Phoenix, Miami, Orlando, and Tampa, with Dallas and Houston already advancing. Austin was noted as “ramping unsupervised,” while the Bay Area remained in safety-driver mode.
By Q1 2026, the deck updated statuses to reflect launches in Dallas and Houston, with “preparations underway” for the remaining cities, including Las Vegas. Paid Robotaxi miles nearly doubled sequentially in Q1, underscoring momentum even as broader timelines adjusted slightly for regulatory and operational readiness.
On earnings calls, CEO Elon Musk and executives have emphasized a phased rollout prioritizing safety. Unsupervised operations in Texas have shown strong results with no reported accidents or injuries in the program. Tesla continues groundwork in additional major U.S. metros through testing and permitting, positioning it to scale quickly once approvals clear.
This Nevada move aligns with Tesla’s vision of transforming from an EV maker into an AI and robotics leader. The forthcoming Cybercab, which started production at Giga Texas in April, is expected to eventually dominate the fleet, replacing many Model Y vehicles and driving down costs to enable affordable rides.
For investors and the industry, this signals Tesla’s intent to dominate key Sun Belt and tourist markets where weather, regulations, and demand favor rapid scaling. Success in Las Vegas could validate the model for denser urban and high-tourism environments, accelerating the shift toward a future where robotaxis generate meaningful revenue.
Las Vegas will also expand knowledge among the general public at Tesla’s capabilities, helping people experience driverless ride-hailing from several companies during their time on The Strip.
Tesla Full Self-Driving is taking over Europe: fourth country gets FSD approval
Tesla revises FSD transfer policy on new Cybertruck trim, causing cancellations
