BYLINE: Greg Cunningham

Newswise — Researchers at the Department of Energy’s Oak Ridge National Laboratory have uncovered a path to design superionic polymer electrolytes for solid-state batteries and other energy applications that could help ensure a future of abundant and reliable energy for the United States. The scientists demonstrated that by carefully controlling the chemical composition of a lithium salt-based polymer, they could create a material that enables superfast transport of ions in batteries and many other energy storage and conversion technologies.

“Researchers around the world are focusing on unlocking the potential of polymer electrolytes because they have a lot of advantages over the conventional liquid electrolytes,” said Catalin Gainaru, an R&D staff scientist of ORNL’s Chemical Sciences Division. “Achieving fast ion transport has always been a major challenge of polymer electrolytes, but our recent research demonstrates that this may no longer be the case.”

Batteries are made up of two electrodes — a cathode and an anode — separated by an electrolyte material. As a battery charges or discharges, ions need to have a high mobility within the electrolyte as they move back and forth between electrodes. Traditional batteries use liquid or gel electrolytes, but the demand for safer and more efficient power storage has spurred interest in solid-state batteries in which the electrolyte is solid, yielding a battery that is faster charging, safer, more compact and durable. 

The challenge of ion transport in solid-state batteries

Many solid-state concepts use ceramic electrolytes that transport ions so effectively that they are known as superionic ceramics. Unfortunately, these ceramics are prone to break due to brittleness. They are also difficult to roll into thin films and don’t adhere well to the electrodes in a battery. The ORNL researchers demonstrated how a polymeric material can achieve a similar superionic state, in which ions can move up to 10 billion times faster than their surroundings, without the shortcomings of liquids and ceramics. 

Polymers are materials formed by long molecular chains made up of small, repeating building blocks. Well-known examples include a variety of plastics, which are usually made up of repeating units containing carbon and other atoms. The ORNL polymer electrolyte contains polar segments that favor the inclusion of lithium salts and strongly enhance the mobility of ions. 

The research, which was published in Materials Today, was performed as part of the DOE Energy Frontier Research Center (EFRC) known as the Fast and Cooperative Ion Transport in Polymer-Based Materials (FaCT) Center. 

“The goal of the FaCT EFRC is to fully understand how to design novel polymers that change the paradigm of ion transport,” said Tomonori Saito, an ORNL distinguished researcher in ORNL’s Chemical Sciences Division. “We developed a very special polymer in which the segments self-organize to provide a high mobility path for the ions to move through.”

A molecular design strategy enables superionic behavior

The key development was the careful tuning of the structure of the polymer by the addition of precise amounts of molecular groups known as zwitterions. These special functional groups carry both positive and negative charges, which increases local polarity but results in a zero charge for the entire macromolecule. By using careful chemical processes, researchers were able to tailor the number of zwitterionic groups attached to the polymer backbone allowing the ions to assemble into pockets. 

In these pockets, ions interact much like conversationalists at a dinner party. At first, small pockets of diffuse conversations form, isolated throughout the material. Add more pockets, though, and the discussions eventually lose individuality and evolve into a pleasant and cohesive hum. That’s when the ions start to flow like good conversation. But add too many zwitterions, and the cohesive hum devolves into a cacophony and ion transport slows back down. 

Researchers found that the sweet spot was achieved by functionalizing around 80 percent of the units of the polymer electrolyte with zwitterionic groups. At this point, the pockets connect into channel-like structures that allow ions to hop back and forth in an orderly fashion with minimal resistance.

The research team plans to build on this promising early-stage research with additional investigations into the fundamental mechanisms that enable the superionic nature of the polymer. Modeling and simulations using ORNL supercomputing resources as well as robotic autonomous chemistry coupled with AI will help understand what drives this fascinating performance, and neutron scattering studies are planned at the Spallation Neutron Source, a DOE Office of Science user facility at ORNL, to observe the interactions at the molecular level. 

While solid-state batteries are a clear application for the new electrolyte, many energy technologies also rely on effective ion transport. Flow batteries, fuel cells, grid-level energy storage and many other applications could benefit from these newly developed polymers. 

“It’s hard to predict all the technologies that could leverage this discovery,” Saito said. “Anything that needs an impermeable barrier layer, but let ions move freely across it, is a potential application.”

The research was funded by the DOE’s Office of Basic Energy Sciences as part of the FaCT EFRC.

UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. 

BYLINE: Dawn Levy

Newswise — Researchers at the Department of Energy’s Oak Ridge National Laboratory developed a method to convert a commonly discarded hydrocarbon polymer into gasoline- and diesel-like fuels. The team has applied for a patent for the discovery, which treats polyethylene — the stuff of white cutting boards and shopping bags — with aluminum chloride-containing molten salts that serve as both solvent and catalyst. The results were published in the Journal of the American Chemical Society.

The scientists closely monitored the chemical reaction that turns the polymer into petrol to learn the secrets of its success. Soft X-ray spectroscopy and nuclear magnetic resonance showed that charged aluminum atoms each bind to three other atoms to create strongly acidic catalytic sites that break long polymer chains into shorter ones. Isotopic labeling and neutron scattering revealed how simpler polymer chains form gasoline-like fuels and more complex chains form diesel-like fuels.

If scaled beyond the laboratory, the process could strengthen U.S. energy security and industrial competitiveness.

“We developed an efficient and selective polyethylene-to-gasoline conversion,” said Liqi Qiu, a postdoctoral researcher at the University of Tennessee, Knoxville, who performed most of the study’s experiments in the ORNL laboratory of Sheng Dai, of ORNL and UTK. Dai, an ORNL Corporate Fellow and section head for separations and polymer chemistry, is a co-corresponding author of the paper.

The experiments produced a gasoline yield of about 60 percent under mild conditions.

“We converted polymer waste to value-added fuels by using commercially available inorganic salts as the reaction media to provide the catalytic sites,” said Zhenzhen Yang, an ORNL staff scientist who was also a co-corresponding author of the paper. “Unlike traditional techniques for converting polymer to fuel, the new process did not require noble-metal catalysts, organic solvents or external hydrogen. This is the first time molten salts were used as media to produce high-value-added chemicals from waste without any catalytic initiator or solvent and at temperature below 200 degrees Celsius.”

That temperature is comparable to a conventional kitchen oven. Previously, converting polyethylene to gasoline required temperatures of 450 to 500 degrees Celsius through pyrolysis, a heat-driven process that breaks long polymer chains into smaller hydrocarbons.

ORNL has pioneered molten salt research since the 1960s, when its Molten Salt Reactor Experiment showed that molten salt mixtures could serve as both fuel and coolant in a nuclear reactor. 

Dai proposed using molten salts to turn polymer waste into fuel. Molten salts are inorganic compounds that remain stable under harsh reaction conditions. 

“The ORNL system solves two fundamental issues,” Dai said. “One, for a stable system, the process can be radically easier to scale up. Two, the previous system needed an initiator to kick off catalytic reactions. However, the ORNL system does not need one.”

ORNL’s Tomonori Saito managed the project and contributed polymer expertise. “In this case we tackled polyethylene, a widely available commodity polymer, using molten salt,” he said. “We’re trying to understand fundamental science that will lead to discoveries and new economic opportunities.”

Achieving that understanding required multidisciplinary expertise and advanced instruments.

At ORNL, to identify hydrocarbon products formed from reactions with various polymer chains, Luke Daemen employed neutron scattering, and Felipe Polo-Garzon used gas chromatography-mass spectrometry.

When the polymer interacted with an aluminum site, it created a positively charged ion of carbon. Qiu, Yang and Dai labeled that carbon ion with deuterium, an isotope of hydrogen, to track its behavior during the reactions. They also used neutrons at ORNL’s Spallation Neutron Source to track hydrogen.

“The polymer contains a lot of hydrogen,” Dai said. “Neutrons are ideal at discerning light elements including hydrogen and its isotopes, such as deuterium.”

To probe structural changes to aluminum sites during the reaction, Yang used the Advanced Light Source at Lawrence Berkeley National Laboratory. Working with Min-Jae Kim and Jinhua Guo there, she used soft X-rays to examine how aluminum sites interacted with the polymer at atomic and electronic levels. Soft X-rays are ideal for imaging lightweight elements like aluminum.

“The aluminum edge shifted to the low-electron-density edge, which means some electron-rich intermediates formed,” Yang said. “We compared the findings with other techniques and confirmed an aromatic ring intermediate can coordinate with aluminum and cause a binding-energy change.”

That change indicated that the aluminum sites were catalytically active.

Back at ORNL, Bobby Sumpter of the Center for Nanophase Materials Sciences conducted simulations to examine the reaction’s energy dynamics, such as formation and transfer of stable carbon ions to hydrocarbons.

At UTK, Michael Koehler used in situ X-ray diffraction to monitor phase changes in the reaction mixture, and Carlos Alberto Steren used nuclear magnetic resonance to examine aluminum sites.

ORNL’s Tao Wang lent expertise in molten salts. ORNL’s Logan Kearney provided high-density polymers and expert suggestions for their valorization paths.

Although the aluminum-site system is catalytically active and inexpensive, it is hygroscopic, meaning it absorbs water and loses stability. Next, the team hopes to explore ways to confine molten salts, maybe with halogens or carbons, to improve separation and processing.

The findings expand options for producing transportation and industrial fuels. “Polymer source material is abundantly available from consumer waste, and our catalyst system, aluminum molten salts, is very cheap,” Qiu said. “This advance may be promising for industry.”

The DOE Office of Science (Materials Sciences and Engineering Division) primarily supported the research as well as the gas chromatography-mass spectrometry work (Chemical Sciences, Geosciences and Biosciences Division, Catalysis Science program). The research employed DOE Office of Science user facilities at ORNL (the Spallation Neutron Source for neutron scattering at the VISION beamline and the Center for Nanophase Materials Sciences for quantum chemistry calculations) and Lawrence Berkeley National Laboratory (the Advanced Light Source for soft X-ray spectra).

UT-Battelle manages ORNL for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. — Dawn Levy

BYLINE: Tina M. Johnson

Newswise — Gevo, an advanced biofuels company based in Colorado, has licensed two patented catalyst technologies from the U.S. Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL) for use in the production of sustainable aviation fuel (SAF).

“This partnership will streamline the transition of ORNL’s catalyst technologies from lab scale to pilot-scale reactors,” said Andrew Sutton, senior scientist in the Manufacturing Science Division at ORNL. “By demonstrating industrial viability, our goal is to accelerate the commercialization of this technology in the U.S., boosting global competitiveness and domestic production of aviation fuel.”

SAF is an alternative fuel made from plant- or waste-based feedstocks. The International Air Transport Association, representing more than 80% of global air traffic, is interested in SAF. Many air carriers have agreed to buy the fuel at scale, but production efficiencies remain an issue.

To meet the challenge, researchers at ORNL developed catalysts that enable a single-step conversion of ethanol to olefins (ETO), which can then be used to produce SAF. A catalyst accelerates chemical reactions and enhances the efficiency of the fuel production process.

In addition to SAF, olefins serve as key building blocks for a wide range of products, including plastics, solvents and surfactants. The global plastics market is poised for continued growth, with forecasts predicting a market worth more than $1.3 trillion by 2033.

Ethanol, commonly derived from agricultural or cellulosic feedstocks, often serves as the basis for SAF production through its conversion to olefins — key intermediates that simplify and reduce the cost of large-scale fuel manufacturing. Building on this foundation, ORNL’s novel conversion process not only achieves high carbon efficiency but does so at equal or lower cost compared with conventional methods.

Through the DOE Technology Commercialization Fund, the partnership was awarded support for a three-year cooperative research and development agreement (CRADA) to advance this technology for pilot-scale operation and industrial commercialization. Gevo will guide the overall process model and provide industry know-how for successful implementation in the company’s pilot reactor.

“Gevo’s collaboration with Oak Ridge National Laboratory focuses on evaluating a novel catalytic process that converts ethanol into valuable fuel precursors and alternative chemicals like butadiene,” said Andrew Ingram, Gevo’s director of process chemistry and catalysis. “This work complements our broader ethanol conversion portfolio but is distinct from both our commercial deployment of Axens’ alcohol-to-jet process and our next-generation ETO platform. If the economics prove out, this pathway could provide a flexible, cost-effective option to scale U.S. bio-based solutions, driven by American innovation that creates new markets and demand for farmers producing feedstocks for energy and materials.”

ORNL provides extensive scale-up expertise, employing advanced characterization capabilities at the Center for Nanophase Materials Sciences, which was used to provide deeper insight into catalytic processes in larger chemical reactors.

Under the CRADA, ORNL will develop catalyst pellets and test their performance in an advanced chemical reactor. Researchers will develop a computational model based on the testing data generated that can accurately predict how the process will behave at scale to clear the way for industrial use. 

Global demand for jet fuel is expected to increase from 106 billion gallons in 2019 to 230 billion gallons by 2050. Expanding SAF use could help the aviation industry meet this demand while advancing U.S. energy independence and security.

This project was supported by DOE’s Alternative Fuels and Feedstocks Office, formerly known as the Bioenergy Technologies Office, through the Chemical Catalysis for Bioenergy (ChemCatBio), a multi-laboratory consortium focused on accelerating the development of catalytic technologies that convert biomass and waste resources into bio-based fuels and chemicals. Initial program funding was provided by ORNL Laboratory Directed Research and Development and Technology Innovation programs.

In addition to Sutton, Stephen Purdy, Meijun Li, Michael Cordon and Hunter Jacobs are currently contributing to the CRADA project. Inventors of the patented technologies include ORNL’s Li and Brian Davison, former ORNL researcher Zhenglong Li and the University of Maryland’s Junyan Zhang. Jennifer Caldwell within Technology Transfer at ORNL negotiated the terms of the licensing agreement. Browse available chemical technologies for licensing.

UT-Battelle manages ORNL for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit https://energy.gov/science. — Tina M. Johnson

Newswise — Researchers at the Department of Energy’s Oak Ridge National Laboratory have developed a deep learning algorithm that analyzes drone, camera and sensor data to reveal unusual vehicle patterns that may indicate illicit activity, including the movement of nuclear materials.

The software monitors routine traffic over time to establish a baseline for “patterns of life,” enabling detection of deviations that could signal something out of place. For example, a surge in overnight truck traffic at a facility which is normally only visited during the day could reveal illegal shipments. 

The research builds on a previous ORNL-developed technology for recognizing specific vehicles from side views. Researchers improved the structure of this software’s deep learning network to provide much broader capabilities than any existing recognition systems, said ORNL’s Sally Ghanem, lead researcher.

“The majority of the current re-identification models require specific views of the car from the same angles. But our model does not have any of these limitations,” Ghanem said. “We can basically put in any view, from any distance, and determine if it is the same vehicle.” That means the top of a truck seen from a drone can be matched with a side view from the ground. 

This precision in recognition was achieved by training the software on hundreds of thousands of publicly available images from surveillance cameras, ground sensors and drones, combined with computer-generated images based on vehicle specifications. ORNL researcher John Holliman built 3D digital models of many car and truck brands, varying the paint jobs, perspectives and lighting conditions to create a wide range of training scenarios. Unlike most vehicle data sets, the ORNL training images also included older vehicle models.

The image set was expanded with footage captured during six data collections around three ORNL campus intersections chosen because vehicles enter and exit by the same route. “We’re using drones to improve the training data because they are very flexible,” Ghanem said. “Drones can circle a vehicle and change their distance to get many angles, so we can simulate images collected from a satellite or at road level.”

To demonstrate that flexibility, ORNL’s Zach Ryan and Jairus Hines piloted a drone hovering 80 feet over the road to ORNL’s High Flux Isotope Reactor, rotating the drone to follow vehicles through turns for multiple perspectives. They also filmed desirable footage of vehicles slightly hidden by tree limbs or traffic lights, and even blurry shots caused by electrical or magnetic interference. 

“The more low-resolution images we include, the more robust the model,” Ghanem said. Unclear footage and nighttime images train the software to more accurately identify vehicles even when visibility is poor, as in some satellite images.

To avoid bias, Ghanem weeded out repetitive images of the same angle or vehicle type. She also taught the algorithm with both correct and incorrect matches, making sure the correct pairs represented different perspectives. These methods prevent the algorithm from choosing based only on obvious similarities, such as front views of white sedans. “By retraining the model on challenging pairs, we make it more capable of tricky matches,” Ghanem said. 

After training, the team tested the software against 10,000 image pairs, evenly split between correct and incorrect matches. The system proved more than 97% accurate. 

The software leverages a series of neural networks – computational models that function similarly to the brain – which can be trained to not only match different viewpoints but derive long-term patterns from the results. “The project supports nuclear nonproliferation, enabling us to identify whether shipment activities are happening at a specific place,” Ghanem said. 

But the algorithm is also precise enough to track an individual vehicle with stickers, dents or other distinguishing features across a variety of sensors, flagging repeated visits to the same location even if the vehicle takes different routes each time. Researchers are exploring possibilities for adapting the algorithm to incorporate information from non-visual sensors. It could also be applied to identifying the shipment of dangerous or illegal substances on other forms of transportation, such as ships and airplanes.

ORNL researchers and staff who contributed to the project, which was funded through ORNL’s Laboratory Directed Research and Development program, include Ghanem, John Holliman, Ryan Kerekes, Andrew Duncan, Jairus Hines, Ken Dayman, and former staff member Zach Ryan. The High Flux Isotope Reactor is a DOE Office of Science user facility.

UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.