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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 quietly doubled the size of its Cybercab fleet within the Robotaxi program in Austin, Texas, over the weekend to well over 100 units.
The move not only establishes more of the steering-wheel-less and pedal-less vehicles within the ride-sharing fleet Tesla has been operating for a year, but it also solidifies a more robust Robotaxi fleet as a whole.
Riders started receiving notifications from the Robotaxi app that stated: “Cybercab fleet has doubled: more rides available.”
I got this notification on the robotaxi app. They are saying the Cybercab fleet has doubled. Glad that they are advertising this pic.twitter.com/FFrnw4FRCF
— Abhimanyu Yadav (@WorldlyReviewer) September 26, 2026
Tesla first launched rides in the Cybercab in early September, although the Robotaxi fleet has been active for over a year, as rides began last Summer. Cybercab is truly Tesla’s most crucial vehicle release yet, as it is the first car any company has built that is geared toward full-fledged and end-to-end autonomy, never needing human intervention for anything.
Only available in Austin at the current time, Cybercab has two seats and has been spotted testing around various U.S. states and regions; Tesla plans to deploy the Cybercab in various U.S. cities in the coming months as a best-case scenario.
Tesla Cybercab gets initial tie-in to localized, in-house cathode plant
The availability of the Cybercab has doubled from just 58 units last Monday to 125 the following Friday. Marking a substantial increase in Cybercab availability, the additional ride-sharing units are more than welcome, as wait times for Cybercabs, especially, were quite high.
The dramatic increase is a sign that demand for Robotaxi is growing and Tesla is feeling more confident that its driverless ride-hailing suite, especially its Full Self-Driving software, is able to handle any traffic situation without explicit direction or supervision from a human being.
Tesla is advancing a fully automated pipeline for the 4680 battery cells used in its all-electric Semi, spanning production from Giga Texas through shipment and direct consumption on the line at the new dedicated Semi Factory in Sparks, Nevada.
The approach was outlined by Tesla at its September 24 Semi Handover event, which launched high-volume production at its new 1.8-million-square-foot plant in Nevada, which sits adjacent to Gigafactory Nevada and is designed for an annual production rate of 50,000 trucks per year.
After years of pilot builds and what was a four-year-long redesign of the truck, Tesla moved the Semi from 2170 batteries to its in-house 4680 cells, which are made in Austin. The change cuts battery mass and total energy while holding range, a key step in making volume production a realistic possibility.
Cells will leave Giga Texas in trailers, and at the Nevada Semi plant, Tesla intends for a dedicated line to unload those trailers automatically, station the cells, and feed them straight into pack and vehicle assembly.
🚨 Tesla plans to use a completely automated unloading process for cells coming from Giga Texas arriving at the Semi factory in Nevada
A line will “consume” cells from the trailer
The goal is to have zero human touch point throughout the entire process. Insane! pic.twitter.com/wdBFM8LC3F
— TESLARATI (@Teslarati) September 25, 2026
Both Lars Moravy, Tesla’s VP of Vehicle Engineering, and Dan Priestley, the Head of Tesla’s Semi program, described the goal as a “zero human touch point” from the moment the trailer arrives in Texas until a finished Semi drives off the production line in Nevada.
The unloading system that Moravy and Priestley described is just one piece of a much broader automation push. The plant uses what Tesla calls the highest-capacity electric monorail conveyance in vehicle manufacturing, carrying frames-in-white simultaneously. Powder-coating replaces conventional paint, and many processes that would normally require operators have been designed out.
Tesla has repeatedly said that “the best part is no part,” and the cell-handling plan extends that philosophy from the cell factory floor in Texas all the way to final assembly in Nevada.
If executed as described, the closed-loop flow would reduce labor, handling damage, and inventory buffers while tightening quality control on a component that represents a large share of the truck’s cost and weight. It also shortens the physical and organizational distance between two factories separated by more than 1,200 miles. The Semi itself now shares a bar-wound stator and other components with the Cybertruck, further linking Tesla’s passenger and commercial production systems.
High-volume output is expected to ramp gradually after the first trucks left the new line in April 2026. Early customers include PepsiCo, DHL, and U.S. Foods. Whether the automated trailer-to-line process reaches the promised zero-touch standard will be visible in the coming months as production scales. For Tesla, the Semi factory is another test of how far it can push “the machine that builds the machine” across sites.
Elon Musk
Elon Musk’s AI Grok Bot can now handle banking while your Tesla FSD handles the road
Elon Musk says Grok Bot can manage your finances through linked bank and investment accounts.
Grok Bot now wants access to your wallet, with SpaceXAI rolling out a new Finance integration for its agent platform that lets users link bank, credit card and investment accounts thereby letting their Bots help manage spending, investments and more. Elon Musk amplified the announcement on X with a short endorsement, “Grok Bot can manage your finances.”
The feature builds on two earlier steps. In early September, Grok gained the ability to answer questions about spending, savings, investments and cash flow using accounts connected through Plaid, starting with users in the U.S. Before that, on August 28, SpaceXAI let Grok Bot buy things online through Link, with users approving every spend request and the Bot receiving a single use card for each payment.
Musk has already shown how far he wants users to push it. In late August, when Tesla investor account Teslaconomics said he was weighing whether to give Grok Bot access to his bank accounts, Musk replied, “Try it out. If Grok Bot messes up, we will make you whole.” That promise goes beyond SpaceXAI’s consumer terms, which make users responsible for what their agents do and generally cap the company’s liability at the greater of fees paid or $100. SpaceXAI’s own documentation recommends requiring approval for purchases and financial transfers.
For Tesla owners, the update lands five days after Tesla brought Grok Bot into its vehicles, letting drivers hand off errands by voice while FSD (Supervised) handles the road. Bot access inside the car is currently limited to SuperGrok Heavy subscribers, though Connectors are open to anyone signed into Grok. With Finance linked, a driver could ask for a spending summary or a check on upcoming bills during the commute.
Grok’s role in the car has grown quickly since Tesla’s Summer Update let it control cabin features by voice. We have been using Grok Bot in our own Tesla for several weeks, and here’s how our latest test went.
Tesla Cybercab fleet doubles to well over 100 units
Tesla has a ‘no human contact’ approach for Semi production
