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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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News
Tesla Europe rolls out FSD ride-alongs in the Netherlands’ holiday campaign
The festive event series comes amid Tesla’s ongoing push for regulatory approval of FSD across Europe.
Tesla Europe has announced that its “Future Holidays” campaign will feature Full Self-Driving (Supervised) ride-along experiences in the Netherlands.
The festive event series comes amid Tesla’s ongoing push for regulatory approval of FSD across Europe.
The Holiday program was announced by Tesla Europe & Middle East in a post on X. “Come get in the spirit with us. Featuring Caraoke, FSD Supervised ride-along experiences, holiday light shows with our S3XY lineup & more,” the company wrote in its post on X.
Per the program’s official website, fun activities will include Caraoke sessions and light shows with the S3XY vehicle lineup. It appears that Optimus will also be making an appearance at the events. Tesla even noted that the humanoid robot will be in “full party spirit,” so things might indeed be quite fun.
“This season, we’re introducing you to the fun of the future. Register for our holiday events to meet our robots, see if you can spot the Bot to win prizes, and check out our selection of exclusive merchandise and limited-edition gifts. Discover Tesla activities near you and discover what makes the future so festive,” Tesla wrote on its official website.
-->This announcement aligns with Tesla’s accelerating FSD efforts in Europe, where supervised ride-alongs could help demonstrate the tech to regulators and customers. The Netherlands, with its urban traffic and progressive EV policies, could serve as an ideal and valuable testing ground for FSD.
Tesla is currently hard at work pushing for the rollout of FSD to several European countries. Tesla has received approval to operate 19 FSD test vehicles on Spain’s roads, though this number could increase as the program develops. As per the Dirección General de Tráfico (DGT), Tesla would be able to operate its FSD fleet on any national route across Spain. Recent job openings also hint at Tesla starting FSD tests in Austria. Apart from this, the company is also holding FSD demonstrations in Germany, France, and Italy.
News
Tesla sees sharp November rebound in China as Model Y demand surges
New data from the China Passenger Car Association (CPCA) shows a 9.95% year-on-year increase and a 40.98% jump month-over-month.
Tesla’s sales momentum in China strengthened in November, with wholesale volumes rising to 86,700 units, reversing a slowdown seen in October.
New data from the China Passenger Car Association (CPCA) shows a 9.95% year-on-year increase and a 40.98% jump month-over-month. This was partly driven by tightened delivery windows, targeted marketing, and buyers moving to secure vehicles before changes to national purchase tax incentives take effect.
Tesla’s November rebound coincided with a noticeable spike in Model Y interest across China. Delivery wait times extended multiple times over the month, jumping from an initial 2–5 weeks to estimated handovers in January and February 2026 for most five-seat variants. Only the six-seat Model Y L kept its 4–8 week estimated delivery timeframe.
The company amplified these delivery updates across its Chinese social media channels, urging buyers to lock in orders early to secure 2025 delivery slots and preserve eligibility for current purchase tax incentives, as noted in a CNEV Post report. Tesla also highlighted that new inventory-built Model Y units were available for customers seeking guaranteed handovers before December 31.
This combination of urgency marketing and genuine supply-demand pressure seemed to have helped boost November’s volumes, stabilizing what had been a year marked by several months of year-over-year declines.
-->For the January–November period, Tesla China recorded 754,561 wholesale units, an 8.30% decline compared to the same period last year. The company’s Shanghai Gigafactory continues to operate as both a domestic production base and a major global export hub, building the Model 3 and Model Y for markets across Asia, Europe, and the Middle East, among other territories.
Tesla bear Michael Burry got blunt with his beliefs over the company’s valuation, which he called “ridiculously overvalued” in a newsletter to subscribers this past weekend.
“Tesla’s market capitalization is ridiculously overvalued today and has been for a good long time,” Burry, who was the inspiration for the movie The Big Short, and was portrayed by Christian Bale.
Burry went on to say, “As an aside, the Elon cult was all-in on electric cars until competition showed up, then all-in on autonomous driving until competition showed up, and now is all-in on robots — until competition shows up.”
Tesla bear Michael Burry ditches bet against $TSLA, says ‘media inflated’ the situation
For a long time, Burry has been skeptical of Tesla, its stock, and its CEO, Elon Musk, even placing a $530 million bet against shares several years ago. Eventually, Burry’s short position extended to other supporters of the company, including ARK Invest.
Tesla has long drawn skepticism from investors and more traditional analysts, who believe its valuation is overblown. However, the company is not traded as a traditional stock, something that other Wall Street firms have recognized.
While many believe the company has some serious pull as an automaker, an identity that helped it reach the valuation it has, Tesla has more than transformed into a robotics, AI, and self-driving play, pulling itself into the realm of some of the most recognizable stocks in tech.
Burry’s Scion Asset Management has put its money where its mouth is against Tesla stock on several occasions, but the firm has not yielded positive results, as shares have increased in value since 2020 by over 115 percent. The firm closed in May.
In 2020, it launched its short position, but by October 2021, it had ditched that position.
Tesla has had a tumultuous year on Wall Street, dipping significantly to around the $220 mark at one point. However, it rebounded significantly in September, climbing back up to the $400 region, as it currently trades at around $430.
It closed at $430.14 on Monday.
Tesla Europe rolls out FSD ride-alongs in the Netherlands’ holiday campaign
Tesla sees sharp November rebound in China as Model Y demand surges
