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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 has officially launched the Model Y L in the United States and Puerto Rico for $61,990. It is the longer-wheelbase version of the Model Y, and has been available in China since last year.
Tesla brings the Model Y L to the U.S. just months after it phased out the only pure SUV in its lineup, the Model X. It is slightly longer than the Model Y configurations that are already available in the U.S., and features a three-row, six-seat setup with Captain’s Chairs being among the many features that make this a truly fantastic offering.
The Model Y L is priced competitively at $61,990, and features 325 miles of range and a 0-60 MPH in just 4.4 seconds.
Tesla also added a handful of new features that are not available in even the Premium Model Y. Here’s a full list of its features:
- Heated/Ventilated Front Seats with Powered Thigh Cushion
- Heated/Ventilated Captain’s Seats in Second Row with Powered Armrests & One-Touch Fold
- Heated Third-Row Seats with Power Recline, One-Touch Fold & Child Seat Anchors
- Improved Airflow, Increased Efficiency, More Range
- 89 cubic feet of trunk space
- Upgraded Acoustic Glass and Suspension to Minimize Road Noise
- Adaptive Damping for a Smooth, Stable Ride
- Staggered Tires for Enhanced Grip
- Larger Tailgate for Better Rear Visibility and Bigger Windows Overall
- 16″ First Row and 8″ Second Row Touchscreens
- 19-Speaker Immersive Tesla Audio
- 50W Wireless Charging Pads with Active Cooling and Charging Ports for All Other Seats
- FSD Supervised and Integrated Grok AI
Tesla is also delivering these first units as a “Launch Series,” which comes with additional features, such as:
- Door Trim Puddle Lights
- Suede Dashboard Wing
- Exterior and Interior Badging
- Floor Mats
- Sill Plates
The launch of the Model Y L in the U.S. marks a huge offering from Tesla to U.S. consumers. People have been calling for Tesla to bring a larger car to the U.S., and it needed it more than ever now that the Model X is gone.
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- Credit: Tesla
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- Credit: Tesla
It is a huge accomplishment for Tesla to get the Model Y L to the U.S., and after reporting strong deliveries today, it will be interesting to see how this car impacts future quarterly delivery reports.
Deliveries for the Model Y L “Launch Series” are slated for September or October of this year.
Tesla just told us twice that the Model Y L is coming to the U.S., and two social media posts definitely just tipped the company’s hand, as if they wanted it to be any other way.
The two social media posts basically confirm that the slightly longer version of the Model Y will be heading to the United States soon, and many have speculated that the company could launch the vehicle as soon as this weekend.
The first post was directly from Tesla, and it showed an incredibly long Dachshund, with words above that said, “Looking forward to the long weekend.”
Looking forward to the long weekend pic.twitter.com/URzH6zOUdn
— Tesla (@Tesla) July 1, 2026
Anyone who knows Tesla knows the company loves to troll its fans and have fun, and this is a perfect example of that. While not a direct acknowledgement, Tesla is very involved on social media, especially CEO Elon Musk’s platform X, and the company is well aware of what is being discussed within the community.
With recent sightings of Model Y L test mules in California, peeks of the vehicle at Giga Texas, and a large call for the car to come to the U.S., Tesla is simply stoking conversation with this.
However, the company also made another move that was recognized on social media. Tesla has a large gallery that includes photos of its products so media and others can use them. This gallery applies to the U.S. market specifically, unless otherwise specified.
Tesla uploaded a Model Y L to the Gallery last night:
This looks like a Model Y L https://t.co/TpnBwrLmH9
— TESLARATI (@Teslarati) July 2, 2026
This seems to be another indication that the Model Y L is coming to the United States.
Musk said last year that the Model Y L could make its way to the United States late this year, but it was not something that was set in stone by Tesla. The company definitely needs to establish something in the SUV market that is larger than the Model Y, and the Model Y L might be the answer.
Even still, there are consumers out there who would love Tesla to develop something even larger, like a competitor to the Tahoe or Expedition. Tesla has not really given much of an indication that it will go in that direction.
Tesla is using the vehicles’ internal microphones to improve build quality, Vice President of Engineering Lars Moravy revealed recently.
It’s no secret that Tesla is always finding ways to make its manufacturing operations more efficient, accurate, and valuable. Constantly trying to make its cars better, the company has never placed any restrictions on what it will do to improve everything from panel gaps to paint.
As Teslas have been driving autonomously on the property of the Gigafactory Texas plant for a while now, Moravy revealed to Herbert Ong in a new interview that cars rolling off production lines now autonomously navigate themselves through a bumps, squeaks, and rattles (BSR) portion of the line. This helps to identify any loose or improperly installed internal parts.
The cabin’s microphones, which are used for a variety of things in ownership, simultaneously monitor any noises inside the vehicle while it rolls through the BSR portion of the production line. Moravy actually revealed that Tesla is trying to build “Full Self-Hearing,” an AI system that will detect minor imperfections so they can be corrected before delivery.
It’s no secret that build quality is something that Tesla struggled with as it scaled to a fully massive production operation that manufactures over 1.6 million vehicles per year. However, in recent years, especially, there have not been as many complaints. Tesla has truly improved upon its build quality and paint quality over the past several years, especially in the U.S.
Tesla’s ‘megacasts’ are key to massive build quality improvements
While those improvements have been evident, there are still some complaints; no automaker is perfect with this. But this step will now ensure that every single car that rolls off the production lines at Gigafactory Texas will be void of any creaks, squeaks, or squeals when it leaves the factory.
This measure is one of the most unique we’ve seen in terms of a strategy to avoid build quality issues, but it is not exclusive to Tesla.
Ford uses acoustic analysis AI to find abnormalities in seat motors, climate control units, and other components. Suppliers and OEMs will also use microphone arrays or particle velocity sensors in end-of-line stations.
The full interview with Lars Moravy is available below:
🚨 If you’re a Tesla investor, this is one interview you don’t want to skip. The full video posted below.
Jeff Lutz @thejefflutz and I sat down with Tesla VP of Engineering Lars Moravy, and it was packed with insights!
A few of the biggest takeaways:
• Cybercab is expected to… pic.twitter.com/fhYSr2dCqP
— Herbert Ong (@herbertong) July 1, 2026
Tesla brings Model Y L ‘Launch Series’ to the U.S. at $61,990
Tesla just told us twice that Model Y L is coming to the U.S.
