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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 receives approval for FSD Supervised tests in Sweden
Tesla confirmed that it has been granted permission to test FSD Supervised vehicles across Sweden in a press release.
Tesla has received regulatory approval to begin tests of its Full Self-Driving Supervised system on public roads in Sweden, a notable step in the company’s efforts to secure FSD approval for the wider European market.
FSD Supervised testing in Sweden
Tesla confirmed that it has been granted permission to test FSD Supervised vehicles across Sweden following cooperation with national authorities and local municipalities. The approval covers the Swedish Transport Administration’s entire road network, as well as urban and highways in the Municipality of Nacka.
Tesla shared some insights into its recent FSD approvals in a press release. “The approval shows that cooperation between authorities, municipalities and businesses enables technological leaps and Nacka Municipality is the first to become part of the transport system of the future. The fact that the driving of the future is also being tested on Swedish roads is an important step in the development towards autonomy in real everyday traffic,” the company noted.
With approval secured for FSD tests, Tesla can now evaluate the system’s performance in diverse environments, including dense urban areas and high-speed roadways across Sweden, as noted in a report from Allt Om Elbil. Tesla highlighted that the continued development of advanced driver assistance systems is expected to pave the way for improved traffic safety, increased accessibility, and lower emissions, particularly in populated city centers.
Tesla FSD Supervised Europe rollout
FSD Supervised is already available to drivers in several global markets, including Australia, Canada, China, Mexico, New Zealand, and the United States. The system is capable of handling city and highway driving tasks such as steering, acceleration, braking, and lane changes, though it still requires drivers to supervise the vehicle’s operations.
Tesla has stated that FSD Supervised has accumulated extensive driving data from its existing markets. In Europe, however, deployment remains subject to regulatory approval, with Tesla currently awaiting clearance from relevant authorities.
The company reiterated that it expects to start rolling out FSD Supervised to European customers in early 2026, pending approvals. It would then be unsurprising if the company secures approvals for FSD tests in other European territories in the coming months.
News
Tesla owners in Sweden get direct attention from pro-union groups
As part of their efforts, the group has started distributing informational leaflets to Tesla vehicles across Stockholm, urging them to pressure the electric vehicle maker to sign a collective agreement.
Amid Tesla Sweden’s ongoing conflict with trade union IF Metall, a group of pro-union supporters has begun directing their attention to actual Tesla owners.
As part of their efforts, the group has started distributing informational leaflets to Tesla vehicles across Stockholm, urging them to pressure the electric vehicle maker to sign a collective agreement.
Leaflets on parked Tesla vehicles
As noted in a Dagens Arbete (DA) report, participants of the protest place yellow information slips on parked Tesla vehicles across parts of Stockholm. The slips resemble parking notices that contain information related to the unions’ ongoing strike against Tesla Sweden.
Participants involved in the activity said the leaflets were intended to inform consumers rather than target individual owners. The action was carried out in public areas, with leaflets placed on windshields of parked vehicles. When vehicle owners are present, organizers said they provide verbal explanations of the labor dispute.
Tesla has not commented publicly about the matter as of writing.
Recurring demonstrations against Tesla
The leaflet distribution effort follows weekly demonstrations that have taken place outside Tesla’s workshop and office in Upplands Väsby, where protesters typically gather to express support for a collective agreement. Those demonstrations have included informational outreach to customers and workers and, at times, police presence, according to prior reporting.
In a comment, one of the protesters stated that even Tesla owners must be concerned about the unions’ conflict with the electric vehicle maker. “You may think it doesn’t concern you, as you only drive a car. But it does, as we all have a responsibility for the rules in Sweden.
“We are not looking to hunt down individual Tesla owners. Rather, this is a way to spread opinion and increase pressure on Tesla. It should have some impact if several Tesla owners come in and say that you should sign a collective agreement,” one of the protesters stated.
Tesla has landed a massive deal to expand its charging infrastructure for heavy-duty electric trucks — and not just theirs, but all manufacturers.
Tesla entered an agreement with Pilot Travel Centers, the largest operator of travel centers in the United States. Tesla’s Semi Chargers, which are used to charge Class 8 electric trucks, will be responsible for providing energy to various vehicles from a variety of manufacturers.
The first sites are expected to open later this Summer, and will be built at select locations along I-5 and I-10, major routes for commercial vehicles and significant logistics companies. The chargers will be available in California, Georgia, Nevada, New Mexico, and Texas.
Each station will have between four and eight chargers, delivering up to 1.2 megawatts of power at each stall.
The project is the latest in Tesla’s plans to expand Semi Charging availability. The effort is being put forth to create more opportunities for the development of sustainable logistics.
Senior Vice President of Alternative Fuels at Pilot, Shannon Sturgil, said:
“Helping to shape the future of energy is a strategic pillar in meeting the needs of our guests and the North American transportation industry. Heavy-duty charging is yet another extension of our exploration into alternative fuel offerings, and we’re happy to partner with a leader in the space that provides turnkey solutions and deploys them quickly.”
Tesla currently has 46 public Semi Charger sites in progress or planned across the United States, mostly positioned along major trucking routes and industrial areas. Perhaps the biggest bottleneck with owning an EV early on was charging availability, and that is no different with electric Class 8 trucks. They simply need an area to charge.
Tesla is spearheading the effort to expand Semicharging availability, and the latest partnership with Pilot shows the company has allies in the program.
The company plans to build 50,000 units of the Tesla Semi in the coming years, and with early adopters like PepsiCo, DHL, and others already contributing millions of miles of data, fleets are going to need reliable public charging.
🚨 Pilot working with Tesla to install and expand Semi Chargers is a perfect example of two industry leaders working together for the greater good.
As more commerce companies expand into EVs, Semi Charger will be more commonly available for electrified fleets, making efforts… pic.twitter.com/VPLIYyq15b
— TESLARATI (@Teslarati) January 27, 2026
Tesla is partnering with other companies for the development of the Semi program, most notably, a conglomeration with Uber was announced last year.
Tesla lands new partnership with Uber as Semi takes center stage
The ride-sharing platform plans to launch the Dedicated EV Fleet Accelerator Program, which it calls a “first-of-its-kind buyer’s program designed to make electric freight more affordable and accessible by addressing key adoption barriers.”
The Semi is one of several projects that will take Tesla into a completely different realm. Along with Optimus and its growing Energy division, the Semi will expand Tesla to new heights, and its prioritization of charging infrastructure.
Tesla receives approval for FSD Supervised tests in Sweden
Tesla owners in Sweden get direct attention from pro-union groups
