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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
SpaceX calls off Starship 10 flight attempt once again
SpaceX is calling off a potential launch of Starship this evening, marking the second consecutive night the tenth test flight of the massive rocket will be delayed.
SpaceX is calling off a potential launch of Starship this evening, marking the second consecutive night the tenth test flight of the massive rocket will be delayed.
Originally planning to launch on Sunday at 6:30 p.m. local time in Starbase, Texas, SpaceX was forced to delay the tenth launch of Starship due to a hardware issue.
“Ground side liquid oxygen leak needs to be fixed. Aiming for another launch attempt tomorrow,” CEO Elon Musk posted on the social media platform X.
Starship Flight 10 rescheduled as SpaceX targets Monday launch
The launch was then pushed to Monday night, and the launch window was set to start at the same time as Sunday. However, SpaceX would push it back to 6:44 p.m. due to some weather issues.
Eventually, Starship seemed like it was trending toward a launch, but weather continued to persist in the area, with thunder, rain, and lightning all threatening in the area.
At around 7:03 p.m., SpaceX decided to stand down once again, confirming weather was the culprit of yet another delay:
Launch called off for tonight due to anvil clouds over launch site (lightning risk)
— Elon Musk (@elonmusk) August 26, 2025
SpaceX will likely try again on Tuesday night, but the company has not yet confirmed if it will open another launch window.
SpaceX is set to launch its tenth test flight of the Starship program, with a launch window that will open at 6:44 p.m. local time, or 7:44 p.m. on the East Coast.
Starship’s tenth test flight was originally scheduled for launch yesterday with a one-hour window that opened at 7:30 p.m. ET, but it was called off 17 minutes before that window even had a chance to open.
Starship Flight 10 rescheduled as SpaceX targets Monday launch
SpaceX moved the flight to tonight. It was also originally scheduled to have a launch window at the same time as Sunday, but it was pushed back 14 minutes to around 6:30 p.m. ET. There are storms in the area, as well as clouds over Starbase, so there is the off chance for another launch delay.
There are several big objectives for this launch, including the expansion of the operating envelope for the Super Heavy booster. SpaceX says there are “multiple landing burn tests planned.”
The booster will also be performing a few in-flight experiments to help with data collection. Specifically, real-world performance data on future flight profiles and off-nominal scenarios will be on the list of things SpaceX will be looking for.
Starship itself will have a few in-flight objectives that include the deployment of eight Starlink simulators that are similar in size to the next-gen satellites for the internet service. SpaceX was set to test this with Starship’s seventh test flight, which occurred in January 2025. However, the task was abandoned as the vehicle was destroyed before deployment could occur.
Liftoff conditions are currently looking favorable, and SpaceX will be eager to improve upon its Starship launch program as CEO Elon Musk has big plans for it in the coming years.
You can watch the launch below via SpaceX:
Watch Starship’s tenth flight test → https://t.co/UIwbeGoo2B https://t.co/MQg9ZAjCip
— SpaceX (@SpaceX) August 25, 2025
Elon Musk
Tesla looks to expand Robotaxi geofence once again with testing in new area
It looks as if Tesla is preparing for its next expansion of the geofence, potentially moving toward a much larger service area that could eclipse 150 square miles.
Tesla looks to be preparing for the potential expansion of the Robotaxi geofence once again, as the company was spotted testing the suite in an area well outside of the Austin service area.
After it first launched the Robotaxi platform on June 22, Tesla has managed to expand its geofence twice, essentially doubling the travel area both times.
The most recent expansion took the size of the geofence from 42 square miles to about 80 square miles, bringing new neighborhoods and regions of the city into the realm of where the driverless vehicles could take passengers.
However, it looks as if Tesla is preparing for its next expansion of the geofence, potentially moving toward a much larger service area that could eclipse 150 square miles.
Over the weekend, one fan noticed a Robotaxi validation vehicle testing in Bee Cave, Texas, which is roughly 25 minutes from the edge of the current geofence:
Tesla spotted doing Robotaxi validation testing in Bee Cave, Texas, about 15 miles west of Austin (20-25 minute drive from current edge of geofence). pic.twitter.com/JCOcoys8SJ
— Sawyer Merritt (@SawyerMerritt) August 23, 2025
Tesla has been testing vehicles in the western suburbs of Austin for some time, and it seems the company is laying some groundwork to push its geofence expansion into Plaid Mode as competition with Waymo continues to be at the forefront of the conversation.
Waymo has been expanding with Tesla for some time, as the pace of expansion for the two companies has been relatively accelerated for the past couple of months.
Tesla’s expansions of the geofence sent a clear message to competitors and doubters, but it is still aiming to keep things safe and not push the envelope too quickly.
The geofence expansion is impressive, but Tesla is also focusing on expanding its vehicle fleet in both Austin and the Bay Area, where it launched a ride-hailing service in July.
Tesla Bay Area autonomous fleet to grow to over 100 units: Elon Musk
Still, safety is the priority at the current time.
“We are being very cautious. We do not want to take any chances, so we are going to go cautiously. But the service areas and the number of vehicles in operation will increase at a hyper-exponential rate,” CEO Elon Musk said during the Q2 Earnings Call.
SpaceX calls off Starship 10 flight attempt once again
WATCH: SpaceX Starship Flight 10 launch
Tesla looks to expand Robotaxi geofence once again with testing in new area
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