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Lithium-ion batteries are everywhere: You see them in gadgets, vehicles, robots, and power-grid storage. Worldwide production now stands at about 160 gigawatt-hours per year. The revolutionary technology earned three of its lead developers the Nobel Prize in Chemistry in 2019.
And yet the lithium-ion battery is far from perfect. It's still too pricey for applications requiring long-term storage, and it has a tendency to catch fire. Many forms of the battery rely on increasingly hard-to-procure materials, like cobalt and nickel. Among battery experts, the consensus is that someday something better will have to come along.
That something may well be the lithium-ion battery's immediate predecessor: the lithium-metal battery. It was developed in the 1970s by M. Stanley Whittingham, then a chemist at Exxon. Metallic lithium is attractive as a battery material because it easily sheds electrons and positively charged lithium ions. But Whittingham's design proved too tricky to commercialize: Lithium is highly reactive, and the titanium disulfide he used for the cathode was expensive. Whittingham and other researchers added graphite to the lithium, allowing the lithium to intercalate and reducing its reactivity, and they swapped in cheaper materials for the cathode. And so the lithium-ion battery was born. Batteries with lithium-metal anodes, meanwhile, seemed destined to remain an interesting side note on the way to lithium-ions.
But XNRGI, based in Bothell, Wash., aims to bring lithium-metal batteries into the mainstream. Its R&D team managed to tame the reactivity of metallic lithium by depositing it into a substrate of silicon that's been coated with thin films and etched with millions of tiny cells. The 3D substrate greatly increases the anode's surface area compared with a traditional lithium-ion's two-dimensional anode. When you factor in using metallic lithium instead of a compound, the XNRGI anode has up to 10 times the capacity of a traditional intercalated graphite-lithium anode, says Chris D'Couto, XNRGI's CEO.
The company expects to begin low-volume commercial production of its lithium-metal batteries this year, for shipment to electric-vehicle and consumer-electronics customers. XNRGI is also targeting grid storage. Last year, it signed an agreement to form a joint venture with the Canadian startup Cross Border Power, to sell and distribute its batteries to utility customers in North America.
Of course, new battery technologies are announced all the time, and tech news outlets, including IEEE Spectrum, are more than happy to tout their promising capabilities. But relatively few batteries that appear promising or even revolutionary in the lab actually make the leap to the marketplace.
Commercializing any new battery is a complicated prospect, notes Venkat Srinivasan, an energy-storage expert at Argonne National Laboratory, near Chicago. “It depends on how many metrics you're trying to satisfy," he says. For an electric car, the ideal battery offers a driving range of several hundred kilometers, charging times measured in minutes, a wide range of operating temperatures, a 10-year life cycle, and safety in collisions. And of course, low cost.
“The more metrics you have, the more difficult it will be for a new battery technology to satisfy them all," Srinivasan says. “So you need to compromise—maybe the battery will last 10 years, but the driving range will be limited, and it won't charge that quickly." Different applications will have different metrics, he adds, and “industry only wants to look at batteries that are at least as good as what's already available."
D'Couto acknowledges that commercializing XNRGI's batteries has not been easy, but he says several factors gave the company a leg up. Rather than inventing a new manufacturing method, it borrowed some of the same tried-and-true techniques that chipmakers use to make integrated circuits. These include the etching of the 20-by-20–micrometer cavities into the silicon and application of the thin films. Hence the battery's name: the PowerChip.
Each of those microscopic cells can be considered a microbattery, D'Couto says. Unlike the catastrophic failure that occurs when a lithium-ion battery is punctured, a failure in one cell of a PowerChip won't propagate to the surrounding cells. The cells also seem to discourage the formation of dendrites, threadlike growths that can cause the battery to fail.
Some flavors of lithium-ion batteries, such as those made by Enovix, Nexeon, Sila Nanotechnologies, and SiON Power, also achieve better performance by replacing some or all of the graphite in the anode with silicon. [See, for example, “To Boost Lithium-Ion Battery Capacity by up to 70%, Add Silicon."] In those batteries' anodes, the lithium is intercalated with the silicon, bonding to form Li15Si4.
In XNRGI's PowerChip, the silicon substrate has a conductive coating that acts as a current collector and a diffusion barrier that prevents the silicon from interacting with the lithium. D'Couto says that the lithium-metal anode's capacity is about five times that of silicon-intercalated anodes.
For most of its existence, XNRGI was known as Neah Power Systems, and it focused on developing fuel cells. The fuel cells used a novel porous silicon substrate. But the fuel-cell market didn't take off, and so in 2016, the company got a Department of Energy grant to use the same concept to build a lithium-metal battery.
XNRGI continues to experiment with cathode designs that can keep up with its supercharged anodes. For now, the company is using cathodes made from lithium cobalt oxide and nickel manganese cobalt, which could yield a battery with twice the capacity of traditional lithium-ions. It's also making sample batteries using cathodes supplied by customers. D'Couto says alternative materials like sulfur could boost the cathode performance even more. “Having a high-performing anode without a corresponding high-performing cathode doesn't maximize the battery's full potential," he says.
“People like me dream of a day where we've completely solved all the battery problems," says Argonne's Srinivasan. “I want everybody to drive an EV, everybody to have battery storage in their home. I want aviation to be electrified," he says. “Meanwhile, my cellphone battery is dying." In batteries as in life, there will always be room for improvement.
Jean Kumagai is the Features Editor at IEEE Spectrum. She holds a bachelor's degree in science, technology, and society from Stanford University and a master's in journalism from Columbia University.
The company’s Earth-2 supercomputer is taking on climate change
Kathy Pretz is editor in chief for The Institute, which covers all aspects of IEEE, its members, and the technology they're involved in. She has a bachelor's degree in applied communication from Rider University, in Lawrenceville, N.J., and holds a master's degree in corporate and public communication from Monmouth University, in West Long Branch, N.J.
Nvidia’s CTO Michael Kagan is an IEEE senior member.
In 2019 Michael Kagan was leading the development of accelerated networking technologies as chief technology officer at Mellanox Technologies, which he and eight colleagues had founded two decades earlier. Then in April 2020 Nvidia acquired the company for US $7 billion, and Kagan took over as CTO of that tech goliath—his dream job.
Nvidia is headquartered in Santa Clara, Calif., but Kagan works out of the company’s office in Israel.
At Mellanox, based in Yokneam Illit, Israel, Kagan had overseen the development of high-performance networking for computing and storage in cloud data centers. The company made networking equipment such as adapters, cables, and high-performance switches, as well as a new type of processor, the DPU. The company’s high-speed InfiniBand products can be found in most of the world’s fastest supercomputers, and its high-speed Ethernet products are in most cloud data centers, Kagan says.
The IEEE senior member’s work is now focused on integrating a wealth of Nvidia technologies to build accelerated computing platforms, whose foundation are three chips: the GPU, the CPU, and the DPU, or data-processing unit. The DPU can support the ability to offload, accelerate, and isolate data center workloads, reducing CPU and GPU workloads.
“At Mellanox we worked on the data center interconnect, but at Nvidia we are connecting state-of-the-art computing to become a single unit of computing: the data center,” Kagan says. Interconnects are used to link multiple servers and combine the entire data center into one, giant computing unit.
“I have access and an open door to Nvidia technologies,” he says. “That’s what makes my life exciting and interesting. We are building the computing of the future.”
Kagan was born in St. Petersburg, Russia—then known as Leningrad. After he graduated high school in 1975, his family moved to Israel. As with many budding engineers, his curiosity led him to disassemble and reassemble things to figure out how they worked. And, with many engineers in the family, he says, pursuing an engineering career was an easy decision.
He attended the Technion, Israel’s Institute of Technology, because “it was one of the best engineering universities in the world,” he says. “The reason I picked electrical engineering is because it was considered to be the best faculty in the Technion.”
Kagan graduated in 1980 with a bachelor’s degree in electrical engineering. He joined Intel in Haifa, Israel, in 1983 as a design engineer and eventually relocated to the company’s offices in Hillsboro, Ore., where he worked on the 80387 floating-point coprocessor. A year later, after returning to Israel, Kagan served as an architect of the i8060XP vector processor and then led and managed design of the Pentium MMX microprocessor.
During his 16 years at Intel, he worked his way up to chief architect. In 1999 he was preparing to move his family to California, where he would lead a high-profile project for the company. Then a former coworker at Intel, Eyal Waldman, asked Kagan to join him and five other acquaintances to form Mellanox.
Alma mater: Technion, Israel’s Institute of Technology, Tel Aviv
Kagan had been turning down offers to join startups nearly every week, he recalls, but Mellanox, with its team of cofounders and vision, drew him in. He says he saw it as a “compelling adventure, an opportunity to build a company with a culture based on the core values I grew up on: excellence, teamwork, and commitment.”
During his more than 21 years there, he said, he had no regrets.
“It was one of the greatest decisions I’ve ever made,” he says. “It ended up benefiting all aspects of my life: professionally, financially—everything.”
InfiniBand, the startup’s breakout product, was designed for what today is known as cloud computing, Kagan says.
“We took the goodies of InfiniBand and bolted them on top of the standard Ethernet,” he says. “As a result, we became the vendor of the most advanced network for high-performance computing. More than half the machines at the top 500 computer companies use the Mellanox interconnect, now the Nvidia interconnect.
“Most of the cloud providers, such as Facebook, Azure, and Alibaba, use Nvidia’s networking and compute technologies. No matter what you do on the Internet, you’re most likely running through the chip that we designed.”
Kagan says the partnership between Mellanox and Nvidia was “natural,” as the two companies had been doing business together for nearly a decade.
“We delivered quite a few innovative solutions as independent companies,” he says.
One of Kagan's key priorities is Nvidia’s Bluefield DPU. The data center infrastructure on a chip offloads, accelerates, and isolates a variety of networking, storage, and security services.Nvidia
As CTO of Nvidia for the past two years, Kagan has shifted his focus from pure networking to the integration of multiple Nvidia technologies including building BlueField data-processing units and the Omniverse real-time graphics collaboration platform.
He says Nvidia’s vision for the data center of the future is based on its three chips: CPU, DPU, and GPU.
“These three pillars are connected with a very efficient and high-performance network that was originally developed at Mellanox and is being further developed at Nvidia,” he says.
Development of the BlueField DPUs is now a key priority for Nvidia. It is a data center infrastructure on a chip, optimized for high-performance computing. It also offloads, accelerates, and isolates a variety of networking, storage, and security services.
“In the data center, you have no control over who your clients are,” Kagan says. “It may very well happen that a client is a bad guy who wants to penetrate his neighbors’ or your infrastructure. You’re better off isolating yourself and other customers from each other by having a segregated or different computing platform run the operating system, which is basically the infrastructure management, the resource management, and the provisioning.”
Kagan is particularly excited about the Omniverse, a new Nvidia product that uses Pixar’s Universal Scene Description software for creating virtual worlds—what has become known as the metaverse. Kagan describes the 3D platform as “creating a world by collecting data and making a physically accurate simulation of the world.”
Car manufacturers are using the Omniverse to test-drive autonomous vehicles. Instead of physically driving a car on different types of roads under various conditions, data about the virtual world can be generated to train the AI models.
“You can create situations that the car has to handle in the real world but that you don’t want it to meet in the real world, like a car crash,” Kagan says. “You don’t want to crash the car to train the model, but you do need to have the model be able to handle hazardous conditions on the road.”
Kagan joined IEEE in 1997. He says membership gives him access to information about technical topics that would otherwise be challenging to obtain.
“I enjoy this type of federated learning and being exposed to new things,” he says.
He adds that he likes connecting with members who are working on similar projects, because he always learns something new.
“Being connected to these people from more diverse communities helps a lot,” he says. “It inspires you to do your job in a different way.”
The Omniverse platform can generate millions of kilometers of synthetic driving data in orders of magnitude faster than actually driving the car.
Nvidia is investing heavily in technology for self-driving cars, Kagan says.
The company is also building what it calls the most powerful AI supercomputer for climate science: Earth-2, a digital twin of the planet. Earth-2 is designed to continuously run models to predict climate and weather events at both the regional and global levels.
Kagan says the climate modeling technology will enable people to try mitigation techniques for global warming and see what their impact is likely to be in 50 years.
The company is also working closely with the health care industry to develop AI-based technologies. Its supercomputers are helping to identify cancer by generating synthetic data to enable researchers to train their models to better identify tumors. Its AI and accelerated computing products also assist with drug discovery and genome research, Kagan says.
“We are actually moving forward at a fairly nice pace,” he says. “But the thing is that you always need to reinvent yourself and do the new thing faster and better, and basically win with what you have and not look for infinite resources. This is what commitment means.”
Standard handsets on Earth, in some locations, will soon connect directly to satellites for remote roaming
Lucas Laursen is a journalist covering global development by way of science and technology with special interest in energy and agriculture. He has lived in and reported from the United States, United Kingdom, Switzerland, and Mexico.
Lynk Tower 1 launched in April 2022, deploying the world’s first commercial cell tower in space.
The next generation of cellphone networks won’t just be 5G or 6G—they will be zero g. In April, Lynk Global launched the first direct-to-mobile commercial satellite, and on 15 August a competitor, AST SpaceMobile, confirmed plans to launch an experimental direct-to-mobile satellite of its own in mid-September. Inmarsat and other companies are working on their own low Earth orbit (LEO) cellular solutions as launch prices drop, satellite fabrication methods improve, and telecoms engineers push new network capabilities.
LEO satellite systems such as SpaceX’s Starlink and Amazon’s Kuiper envision huge constellations of satellites. However, the U.S. Federal Communications Commission just rejected SpaceX’s application for some of the US $9 billion federal rural broadband fund—in part because the Starlink system requires a $600 ground station. Space-based cell service would not require special equipment, making it a potential candidate for rural broadband funds if companies can develop solutions to the many challenges that face satellite-based smartphone service.
“The main challenge is the link budget,” says electrical engineer Symeon Chatzinotas of the University of Luxembourg, referring to the amount of power required to transmit and receive data between satellites and connected devices. “Sending signals to smartphones outdoors could be feasible by using low Earth orbit satellites with sizable antennas in the sky. However, receiving info would be even more challenging since the smartphone antennas usually disperse their energy in all directions.”
“From a nerdy engineering perspective, what’s happening is that network architectures are diverging.” —Derek Long, Cambridge Consultants
The typical distance from a phone to an LEO satellite might be 500 kilometers, at least two orders of magnitude more than typical signal-transmission distances in urban settings, so the dispersion of the phone’s power would be at least eight times greater, and would be further complicated by the phone’s orientation. It is unlikely that a satellite-smartphone connection would work well when the handset is inside a building, for example.
Lynk Global’s initial offering, which it predicts will be available in late 2022, is narrowband—meaning limited voice calls, texting, and Internet of Things (IoT) traffic. That might not allow plutocrats to make 4K video calls from their ocean-faring yachts, but it would be enough for ship insurance companies or rescue services to remain in contact with vessels in places where they couldn’t be reached before, using off-the-shelf cellular devices. AST SpaceMobile’s is aiming for 4G and 5G broadband service for mobiles.
AST satellites will use a phased-array antenna, which consists of many antennas fanned out around the satellite. Each portion of the antenna will transmit within a well-defined cone terminating at the Earth’s surface; that will be the space-to-Earth equivalent of a cell originating from a single ground base station. The company plans for an initial fleet of 20 satellites to cover the equator and help fund the launch of subsequent satellites providing more global coverage.
The size of the coverage zone on the ground should exceed the limited size of those created by Alphabet’s failed balloon-based Project Loon. Broader coverage areas should allow AST to serve more potential customers with the same number of antennas. The low Earth orbit AST is experimenting with yields round-trip signal travel times of around 25 milliseconds or less, an order of magnitude faster than is the case for higher-orbit geostationary satellites that have provided satellite telephony until now.
Plenty of behind-the-scenes technical work remains. The relatively high speed of LEO satellites will also cause a Doppler shift in the signals for which the network will have to compensate, according to a recent review in IEEE Access. New protocols for handoffs between satellites and terrestrial towers will also have to be created so that an active call can be carried from one cell to the next.
The international telecoms standards group 3GPP began providing guidelines for so-called nonterrestrial networks in March in the 17th iteration of its cellular standards. “Nonterrestrial networks” refers not just to LEO satellites but also high-altitude platforms such as drones or balloons. Nonterrestrial networks will need further updates to 3GPP’s standards to accommodate their new network architecture, such as the longer distances between cell base stations and devices.
For example, Stratospheric Platforms earlier this year tested a drone-based network prototype that would fly at altitudes greater than 18,000 meters. Its behavior as part of a 5G network will differ from that of a Lynk Global or AST satellite.
“From a nerdy engineering perspective, what’s happening is that network architectures are diverging. On the one hand, small cells are replacing Wi-Fi. On the other hand [telecom operators] are going to satellite-based systems with very wide coverage. In the middle, traditional macrocells, which are kind of difficult economically, are being squeezed,” says Derek Long, head of telecommunications at Cambridge Consultants. The company has advised Stratospheric Platforms and other companies working on nonterrestrial networks.
If telecom operators succeed, users won’t even notice their space-age smartphone networks.
“When you buy a phone, you expect it to work. Not just where someone says it will work, but everywhere. This is a step toward making that a possibility,” Long says.
Fuel cell electric vehicles (FCEVs) often reach higher energy density and exhibit greater efficiency than battery EVs; however, they also have high manufacturing costs, limited service life, and relatively low power density.
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