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University of Michigan uses recycled Kevlar fiber to solve lithium-sulfur battery life cycle issues

(Credit: University of Michigan)

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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.”

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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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Joey has been a journalist covering electric mobility at TESLARATI since August 2019. In his spare time, Joey is playing golf, watching MMA, or cheering on any of his favorite sports teams, including the Baltimore Ravens and Orioles, Miami Heat, Washington Capitals, and Penn State Nittany Lions. You can get in touch with joey at joey@teslarati.com. He is also on X @KlenderJoey. If you're looking for great Tesla accessories, check out shop.teslarati.com

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Tesla officially begins sunset of Model S and Model X

In the latest move to show Tesla is planning to eliminate the Model S and Model X from production, the company’s Korean arm has officially set a firm cutoff date of March 31, 2026, for new orders of both models.

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Credit: Tesla

Tesla has officially started its process of sunsetting the Model S and Model X just months after the company confirmed it would stop producing the two flagship vehicles in 2026.

This step marks the end of an era for the vehicles that helped establish not only Tesla’s prowess as an automaker but also its status as a disruptor in the entire car industry. While these two cars have done a tremendous amount for Tesla, the signal that it is time to wind down their production has evidently arrived.

In the latest move to show Tesla is planning to eliminate the Model S and Model X from production, the company’s Korean arm has officially set a firm cutoff date of March 31, 2026, for new orders of both models.

This is the first time Tesla has announced a hard global deadline for the Model S and X, as after that date, only existing inventory will be available in South Korea.

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The move to bring closure to the Model S and Model X aligns with CEO Elon Musk’s plans for Tesla moving forward. During the Q4 2025 Earnings Call in January, Musk said the two cars deserved an “honorable discharge” for what they have done for the company.

The long-running programs are primarily being removed so that manufacturing lines can be repurposed for high-volume manufacturing of the Optimus humanoid robot. Tesla is targeting a production rate of up to one million units each year.

The Model S and Model X being removed from Tesla’s plans is a tough choice, but it was one that was written on the wall. Sales of these premium models have declined sharply in recent years, and even with Plaid configurations that are performance-forward, the company still has had trouble getting them sold.

In 2025, the Model S and Model X together accounted for roughly 3 percent of Tesla’s global deliveries, down significantly from prior periods as competition intensified in the luxury EV segment and buyers shifted toward more affordable options like the Model 3 and Model Y.

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The Model S saw sales drop over 50 percent year-over-year in some quarters, while the Model X faced similar pressures from rivals, including the Rivian R1S and BMW iX.

Despite their dwindling volume, the Model S and Model X remain technological showcases. The Plaid variants deliver blistering acceleration, advanced Full Self-Driving capability, and luxurious interiors.

The phase-out paves the way for Tesla’s strategic pivot toward autonomy, robotics, and higher-volume vehicles.

Tesla brings closure to flagship ‘sentimental’ models, Musk confirms

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Fremont will continue producing the refreshed Model 3 and Model Y, ensuring the factory remains a key automotive hub while expanding into robotics. Tesla has stated that the shift is not expected to result in job losses and could increase headcount as Optimus production ramps up.

For Tesla fans, the sunset represents a bittersweet moment. The Model S, introduced in 2012, proved EVs could compete with luxury sedans, while the Falcon-wing-door Model X set new standards for family haulers. Owners can expect continued software support and service for years to come.

Many fans have pushed for the Model X to hang around due to its appeal for families.

With the two cars heading out, Tesla’s priority now becomes its future products, especially that of the Optimus robot, which is the main reason for the S/X platform’s conclusion.

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Tesla shows off mysterious vehicle at Giga Texas

The mysterious structure, partially unboxed amid construction materials, has sparked widespread speculation among Tesla enthusiasts and analysts. Many are convinced it is the long-rumored Model Y L, the extended-wheelbase variant already popular in China, now arriving in Texas for potential U.S. production.

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Credit: Joe Tegtmeyer | X

Tesla seemingly showed off a mysterious vehicle at Giga Texas, one that seems to be completely different than anything the company currently makes for the U.S. market.

The vehicle, which was spotted on the plant’s property, appears to be similar to the Model Y L that has not yet launched in North America, and is currently built at Gigafactory Shanghai in China.

Drone pilot Joe Tegtmeyer captured intriguing footage at Tesla’s Giga Texas on March 23, 2026, revealing what appears to be a large, blue plastic-wrapped vehicle body resting inside a wooden shipping crate outdoors.

The mysterious structure, partially unboxed amid construction materials, has sparked widespread speculation among Tesla enthusiasts and analysts. Many are convinced it is the long-rumored Model Y L, the extended-wheelbase variant already popular in China, now arriving in Texas for potential U.S. production.

The images show an elongated silhouette that stands out from standard Model Y bodies. Side-by-side comparisons shared in replies to Tegtmeyer’s post highlight key differences: the rear door extends farther over the wheel arch than on a regular Model Y, and the rear glass appears to run all the way to the spoiler lip without the metal trim seen on shorter versions.

One overlay analysis noted that the visible proportions align precisely with the Chinese-market Model Y L, which measures approximately 4.98 meters long with a 3.04-meter wheelbase, which is about seven inches longer overall than the standard Model Y sold in the U.S.

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The vehicle is a bare “body-in-white” shell, typical of prototypes sent abroad for tooling validation and local manufacturing ramp-up. Tesla has already launched the six- and seven-seat Model Y L in China and other markets, where it offers roughly 10% more cargo space and greater family-friendly versatility.

This sighting fits Tesla’s broader strategy. Industry observers expect the company to localize Model Y L production at Giga Texas by mid-2026 to serve American families seeking extra room without stepping up to the larger Cybertruck or a future full-size SUV.

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Bringing the design stateside could add tens of thousands of annual deliveries while leveraging existing Model Y lines. People have been adamant that they want the Model Y L in the U.S., especially as Tesla plans to fade the Model X, the company’s most ideal vehicle for large families, out of production in the near future.

Tesla Model Y lineup expansion signals an uncomfortable reality for consumers

While Tesla has made no official comment, the timing, amid Giga Texas expansion and steady Model Y output, suggests the mysterious crate is more than a random prototype.

If confirmed as the Model Y L, it marks another step in Tesla’s effort to refresh its bestselling SUV for global demand. The vehicle would perform exceptionally well in the U.S., and despite the company’s rather mute stance on bringing it to America, this might be the biggest hint to date that it could be on the way.

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Cybertruck

Tesla Cybertruck just won a rare and elusive crash safety honor

Only the most outstanding of performances in crash tests can warrant an IIHS Top Safety Pick+ award, as vehicles listed with that ranking must achieve “Good” ratings in the small overlap front, updated side, and updated moderate overlap front tests, along with “Acceptable” or “Good” headlights standard on all trims.

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(Credit: Tesla)

Tesla Cybertruck landed a rare and elusive safety honor from the Insurance Institute for Highway Safety (IIHS). It was the only pickup truck in the U.S. market to do so.

The IIHS rewarded the Cybertruck with the Top Safety Pick+ honors, the highest marks a vehicle can receive from the agency.

Only the most outstanding of performances in crash tests can warrant an IIHS Top Safety Pick+ award, as vehicles listed with that ranking must achieve “Good” ratings in the small overlap front, updated side, and updated moderate overlap front tests, along with “Acceptable” or “Good” headlights standard on all trims.

Cybertruck was the only truck to also win an NHTSA Five-Star Safety rating, making it the only pickup available on the market to be recognized with top marks from both agencies.

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There are a multitude of options for pickups in the U.S. market, as it is one of the most popular vehicle types for consumers in the country. Pickups are great vehicles for anyone who does any sort of hauling or is just looking for extra space for any variety of reasons.

Pickups are also inherently safer than other body types on the road, mostly because they are larger and heavier, making them more favorable against other vehicle types in the event of a collision. However, Tesla has a significant advantage in safety with its vehicles because it engineers them to not only be safer in collisions, but also easier to repair.

The Cybertruck managed to achieve “Good” ratings, the highest marks available by the IIHS, in all three Crashworthiness categories, as well as “Good” ratings in both Crash Avoidance and Mitigation assessments.

It also received “Good” ratings across all driver and pedestrian crash-test performance metrics, except for one, where it earned an “Acceptable” rating for rear passengers in the Chest category.

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The Cybertruck’s outstanding crash test performance has won it this incredible mark as the pickup still tends to be one of the more polarizing vehicle designs on the market.

It is no secret that Tesla has struggled with demand of the Cybertruck due to pricing, but the recent rollout of a trim that was temporarily priced at just $59,990 showed plenty of people want the all-electric pickup.

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