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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.”

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.

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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.

I’d love to hear from you! If you have any comments, concerns, or questions, please email me at joey@teslarati.com. You can also reach me on Twitter @KlenderJoey, or if you have news tips, you can email us at tips@teslarati.com.

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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 Model Y has become the most common vehicle in Norway

The Tesla Model Y passed more than 70,000 registrations recently.

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Credit: Tesla

The Tesla Model Y has become the most common car on Norwegian roads. This is a remarkable achievement for the all-electric crossover, which has also commanded the top spot in Norway’s vehicle sales rankings for several years running.

Model Y Domination

As per vehicle registration figures tracked by the Norwegian Road Traffic Information Council (OFV), there were 68,378 Model Ys with Norwegian license plates at the end of March/beginning of April 2025. In recent weeks, the Model Y passed more than 70,000 registrations, as per a report from Elbil24.

With the Model Y now becoming the most common car in Norway, the Toyota Rav4 now stands in second place, followed by the Nissan Leaf, the Volkswagen Golf, and the Toyota Yaris. The Model Y also topped the country’s vehicle registration rankings for the last three years, and it set a record for selling the most vehicles in a year in 2023, breaking the Volkswagen Beetle’s record that has stood since 1969.

Possibly More Momentum

It is undeniable that the Tesla Model Y has helped Norway push its electric vehicle transition. As of date, electric vehicles now account for 28% of the Norwegian car fleet, a notable portion of which is comprised of the all-electric crossover.

While the Model Y’s achievements in Norway have been impressive, the vehicle could expand its reach into the country even more this year. Tesla, after all, has been aggressively pushing the new Model Y to consumers, with the company offering a zero percent interest promotion for the vehicle. These efforts, as well as the new Model Y’s improved features, should make the vehicle even more compelling to Norwegian car buyers this year.

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Tesla Board Chair slams Wall Street Journal over alleged CEO search report

Denholm’s comments were posted by Tesla on its official account on social media platform X.

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robyn-m-denholm-tesla
CeBIT Australia, CC BY 2.0 , via Wikimedia Commons

Tesla Board Chair Robyn Denholm has issued a stern correction to The Wall Street Journal after the publication posted a report alleging that the electric vehicle maker’s Board of Directors opened a search for a new CEO to replace Elon Musk.

Denholm’s comments were posted by Tesla on its official account on social media platform X. 

The WSJ’s Allegations

Citing people reportedly familiar with the discussions, the WSJ alleged that Tesla Board members reached out to several executive search firms to work on a formal process for finding Elon Musk’s successor. The publication also alleged that tensions had been mounting at Tesla due to the company’s dropping sales and profits, as well as the time Musk has been spending with DOGE.

The publication also alleged that Elon Musk had met with the Tesla Board about the matter, and that members told the CEO that he needed to spend more time on Tesla. Musk was reportedly instructed to state his intentions publicly as well. The CEO did not push back against the Board, the WSJ claimed. 

Elon Musk did announce that he is stepping back from his day-to-day role at the Department of Government Efficiency during the Tesla Q1 2025 earnings call. Musk’s announcement was embraced by Tesla investors and analysts, many of whom felt that the CEO’s renewed focus on the EV maker could push the company to greater heights. 

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Tesla and Musk’s Response

In response to The Wall Street Journal’s report, Tesla’s official account on X shared a comment from its Board Chair. In her comment, Denham noted that the WSJ‘s report was “absolutely false.” She also highlighted that Tesla had communicated this fact to the publication before the report was published, but the Journal ran the story anyway.

“Earlier today, there was a media report erroneously claiming that the Tesla Board had contacted recruitment firms to initiate a CEO search at the company. This is absolutely false (and this was communicated to the media before the report was published). The CEO of Tesla is Elon Musk and the Board is highly confident in his ability to continue executing on the exciting growth plan ahead,” Denholm stated.

Elon Musk himself commented on the matter, stating that the publication showed an “extremely bad breach of ethics” since the report did not even include the Tesla Board of Directors’ denial of the allegations. “It is an EXTREMELY BAD BREACH OF ETHICS that the WSJ would publish a DELIBERATELY FALSE ARTICLE and fail to include an unequivocal denial beforehand by the Tesla board of directors!” Musk wrote in a post on X.

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Elon Musk

Elon Musk is now a remote DOGE worker: White House Chief of Staff

The Tesla and SpaceX CEO Elon Musk is no longer working from the West Wing.

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Credit: Elon Musk/X

In a conversation with the New York Post, White House Chief of Staff Susie Wiles stated that Tesla and SpaceX CEO Elon Musk is no longer working from the West Wing.

As per the Chief of Staff, Musk is still working for DOGE—as a remote worker, at least.

Remote Musk

In her conversation with the publication, Wiles stated that she still talks with Musk. And while the CEO is now working remotely, his contributions still have the same net effect. 

“Instead of meeting with him in person, I’m talking to him on the phone, but it’s the same net effect,” Wiles stated, adding that “it really doesn’t matter much” that the CEO “hasn’t been here physically.” She also noted that Musk’s team will not be leaving.

“He’s not out of it altogether. He’s just not physically present as much as he was. The people that are doing this work are here doing good things and paying attention to the details. He’ll be stepping back a little, but he’s certainly not abandoning it. And his people are definitely not,” Wiles stated.

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Back to Tesla

Musk has been a frequent presence in the White House during the Trump administration’s first 100 days in office. But during the Q1 2025 Tesla earnings call, Musk stated that he would be spending substantially less time with DOGE and substantially more time with Tesla. Musk did emphasize, however, that DOGE’s work is extremely valuable and critical.

“I think I’ll continue to spend a day or two per week on government matters for as long as the President would like me to do so and as long as it is useful. But starting next month, I’ll be allocating probably more of my time to Tesla and now that the major work of establishing the Department of Government Efficiency is done,” Musk stated.

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