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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’s new Full Self-Driving pricing strategy will eliminate one recurring complaint that many owners have had in the past: FSD transfers.
In the past, if a Tesla owner purchased the Full Self-Driving suite outright, the company did not allow them to transfer the purchase to a new vehicle, essentially requiring them to buy it all over again, which could obviously get pretty pricey.
This was until Q3 2023, when Tesla allowed a one-time amnesty to transfer Full Self-Driving to a new vehicle, and then again last year.
Tesla is now allowing it to happen again ahead of the February 14th deadline.
The program has given people the opportunity to upgrade to new vehicles with newer Hardware and AI versions, especially those with Hardware 3 who wish to transfer to AI4, without feeling the drastic cost impact of having to buy the $8,000 suite outright on several occasions.
Now, that issue will never be presented again.
Last night, Tesla CEO Elon Musk announced on X that the Full Self-Driving suite would only be available in a subscription platform, which is the other purchase option it currently offers for FSD use, priced at just $99 per month.
Tesla is shifting FSD to a subscription-only model, confirms Elon Musk
Having it available in a subscription-only platform boasts several advantages, including the potential for a tiered system that would potentially offer less expensive options, a pay-per-mile platform, and even coupling the program with other benefits, like Supercharging and vehicle protection programs.
While none of that is confirmed and is purely speculative, the one thing that does appear to be a major advantage is that this will completely eliminate any questions about transferring the Full Self-Driving suite to a new vehicle. This has been a particular point of contention for owners, and it is now completely eliminated, as everyone, apart from those who have purchased the suite on their current vehicle.
Now, everyone will pay month-to-month, and it could make things much easier for those who want to try the suite, justifying it from a financial perspective.
The important thing to note is that Tesla would benefit from a higher take rate, as more drivers using it would result in more data, which would help the company reach its recently-revealed 10 billion-mile threshold to reach an Unsupervised level. It does not cost Tesla anything to run FSD, only to develop it. If it could slice the price significantly, more people would buy it, and more data would be made available.
News
Tesla Model 3 and Model Y dominates U.S. EV market in 2025
The figures were detailed in Kelley Blue Book’s Q4 2025 U.S. Electric Vehicle Sales Report.
Tesla’s Model 3 and Model Y continued to overwhelmingly dominate the United States’ electric vehicle market in 2025. New sales data showed that Tesla’s two mass market cars maintained a commanding segment share, with the Model 3 posting year-to-date growth and the Model Y remaining resilient despite factory shutdowns tied to its refresh.
The figures were detailed in Kelley Blue Book’s Q4 2025 U.S. Electric Vehicle Sales Report.
Model 3 and Model Y are still dominant
According to the report, Tesla delivered an estimated 192,440 Model 3 sedans in the United States in 2025, representing a 1.3% year-to-date increase compared to 2024. The Model 3 alone accounted for 15.9% of all U.S. EV sales, making it one of the highest-volume electric vehicles in the country.
The Model Y was even more dominant. U.S. deliveries of the all-electric crossover reached 357,528 units in 2025, a 4.0% year-to-date decline from the prior year. It should be noted, however, that the drop came during a year that included production shutdowns at Tesla’s Fremont Factory and Gigafactory Texas as the company transitioned to the new Model Y. Even with those disruptions, the Model Y captured an overwhelming 39.5% share of the market, far surpassing any single competitor.
Combined, the Model 3 and Model Y represented more than half of all EVs sold in the United States during 2025, highlighting Tesla’s iron grip on the country’s mass-market EV segment.
Tesla’s challenges in 2025
Tesla’s sustained performance came amid a year of elevated public and political controversy surrounding Elon Musk, whose political activities in the first half of the year ended up fueling a narrative that the CEO’s actions are damaging the automaker’s consumer appeal. However, U.S. sales data suggest that demand for Tesla’s core vehicles has remained remarkably resilient.
Based on Kelley Blue Book’s Q4 2025 U.S. Electric Vehicle Sales Report, Tesla’s most expensive offerings such as the Tesla Cybertruck, Model S, and Model X, all saw steep declines in 2025. This suggests that mainstream EV buyers might have had a price issue with Tesla’s more expensive offerings, not an Elon Musk issue.
Ultimately, despite broader EV market softness, with total U.S. EV sales slipping about 2% year-to-date, Tesla still accounted for 58.9% of all EV deliveries in 2025, according to the report. This means that out of every ten EVs sold in the United States in 2025, more than half of them were Teslas.
News
Tesla Model 3 and Model Y earn Euro NCAP Best in Class safety awards
“The company’s best-selling Model Y proved the gold standard for small SUVs,” Euro NCAP noted.
Tesla won dual categories in the Euro NCAP Best in Class awards, with the Model 3 being named the safest Large Family Car and the Model Y being recognized as the safest Small SUV.
The feat was highlighted by Tesla Europe & Middle East in a post on its official account on social media platform X.
Model 3 and Model Y lead their respective segments
As per a press release from the Euro NCAP, the organization’s Best in Class designation is based on a weighted assessment of four key areas: Adult Occupant, Child Occupant, Vulnerable Road User, and Safety Assist. Only vehicles that achieved a 5-star Euro NCAP rating and were evaluated with standard safety equipment are eligible for the award.
Euro NCAP noted that the updated Tesla Model 3 performed particularly well in Child Occupant protection, while its Safety Assist score reflected Tesla’s ongoing improvements to driver-assistance systems. The Model Y similarly stood out in Child Occupant protection and Safety Assist, reinforcing Tesla’s dual-category win.
“The company’s best-selling Model Y proved the gold standard for small SUVs,” Euro NCAP noted.
Euro NCAP leadership shares insights
Euro NCAP Secretary General Dr. Michiel van Ratingen said the organization’s Best in Class awards are designed to help consumers identify the safest vehicles over the past year.
Van Ratingen noted that 2025 was Euro NCAP’s busiest year to date, with more vehicles tested than ever before, amid a growing variety of electric cars and increasingly sophisticated safety systems. While the Mercedes-Benz CLA ultimately earned the title of Best Performer of 2025, he emphasized that Tesla finished only fractionally behind in the overall rankings.
“It was a close-run competition,” van Ratingen said. “Tesla was only fractionally behind, and new entrants like firefly and Leapmotor show how global competition continues to grow, which can only be a good thing for consumers who value safety as much as style, practicality, driving performance, and running costs from their next car.”
Tesla Full Self-Driving pricing strategy eliminates one recurring complaint
Tesla Model 3 and Model Y dominates U.S. EV market in 2025
