Oak Ridge Today

ORNL researchers discover new state of water molecule

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berylCoverImage_horz

ORNL researchers discovered that water in beryl displays some unique and unexpected characteristics. (Photo by Jeff Scovil)

 

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid, or solid states.

In a paper published in Physical Review Letters, researchers at the U.S. Department of Energy’s Oak Ridge National Laboratory describe a new tunneling state of water molecules confined in hexagonal ultra-small channels—5 angstrom across—of the mineral beryl. An angstrom is 1/10-billionth of a meter, and individual atoms are typically about 1 angstrom in diameter.

The discovery, made possible with experiments at ORNL’s Spallation Neutron Source and the Rutherford Appleton Laboratory in the United Kingdom, demonstrates features of water under ultra confinement in rocks, soil, and cell walls, which scientists predict will be of interest across many disciplines.

“At low temperatures, this tunneling water exhibits quantum motion through the separating potential walls, which is forbidden in the classical world,” said lead author Alexander Kolesnikov of ORNL’s Chemical and Engineering Materials Division. “This means that the oxygen and hydrogen atoms of the water molecule are ‘delocalized’ and therefore simultaneously present in all six symmetrically equivalent positions in the channel at the same time. It’s one of those phenomena that only occur in quantum mechanics and has no parallel in our everyday experience.” [Read more…]

Rubber meets the road with new ORNL carbon, battery technologies

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Recycled Tire Battery Schematics

ORNL researchers’ goal is to scale up the recovery process and demonstrate applications as anodes for lithium-ion batteries in large-format pouch cells. (Image courtesy ORNL)

 

Recycled tires could see new life in lithium-ion batteries that provide power to plug-in electric vehicles and store energy produced by wind and solar, say researchers at Oak Ridge National Laboratory.

By modifying the microstructural characteristics of carbon black, a substance recovered from discarded tires, a team led by Parans Paranthaman and Amit Naskar is developing a better anode for lithium-ion batteries. An anode is a negatively charged electrode used as a host for storing lithium during charging.

The method, outlined in a paper published in the journal RSC Advances, has numerous advantages over conventional approaches to making anodes for lithium-ion batteries.

“Using waste tires for products such as energy storage is very attractive not only from the carbon materials recovery perspective but also for controlling environmental hazards caused by waste tire stock piles,” Paranthaman said.

The ORNL technique uses a proprietary pretreatment to recover pyrolytic carbon black material, which is similar to graphite but man-made. When used in anodes of lithium-ion batteries, researchers produced a small, laboratory-scale battery with a reversible capacity that is higher than what is possible with commercial graphite materials. [Read more…]

‘Atomic switcheroo’ explains origins of thin-film solar cell mystery

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Current Maps

Cross-sectional electron beam-induced current maps show the difference in cadmium telluride solar cells before (pictured above) and after (below) cadmium chloride treatment. The increased brightness after treatment indicates higher current collection at the grain boundaries. (Submitted photo)

Treating cadmium-telluride (CdTe) solar cell materials with cadmium-chloride improves their efficiency, but researchers have not fully understood why. Now, an atomic-scale examination of the thin-film solar cells led by Oak Ridge National Laboratory has answered this decades-long debate about the materials’ photovoltaic efficiency increase after treatment.

A research team from ORNL, the University of Toledo, and the U.S. Department of Energy’s National Renewable Energy Laboratory used electron microscopy and computational simulations to explore the physical origins of the unexplained treatment process. The results are published in Physical Review Letters, or PRL.

Thin-film CdTe solar cells are considered a potential rival to silicon-based photovoltaic systems because of their theoretically low cost per power output and ease of fabrication. Their comparatively low historical efficiency in converting sunlight into energy, however, has limited the technology’s widespread use, especially for home systems. [Read more…]

ORNL microscopy system delivers real-time view of battery electrochemistry

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ORNL Battery Electrochemistry

A new in situ transmission electron microscopy technique enabled ORNL researchers to image the snowflake-like growth of the solid electrolyte interphase from a working battery electrode. (Photo courtesy ORNL)

Using a new microscopy method, researchers at Oak Ridge National Laboratory can image and measure electrochemical processes in batteries in real time and at nanoscale resolution.

Scientists at ORNL used a miniature electrochemical liquid cell that is placed in a transmission electron microscope to study an enigmatic phenomenon in lithium-ion batteries called the solid electrolyte interphase, or SEI, as described in a study published in Chemical Communications.

The SEI is a nanometer-scale film that forms on a battery’s negative electrode due to electrolyte decomposition. Scientists agree that the SEI’s formation and stability play key roles in controlling battery functionality. But after three decades of research in the battery field, details of the SEI’s dynamics, structure, and chemistry during electrochemical cycling are still debated, stemming from inherent difficulties in studying battery electrode materials in their native liquid environment.

“We’ve used this novel in situ method to understand the dynamics of how this layer forms and evolves during battery operation,” said Raymond Unocic, ORNL research and development staff scientist. [Read more…]

Neutrons, electrons, and theory reveal secrets of natural gas reserves

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Scanning Electronic Microscope Image of Unconventional Gas Reservoir

A scanning electron microscope image illustrating mineralogy and texture of an unconventional gas reservoir. Note that nanoporosity is not resolvable with this image. SANS and USANS analysis is required to quantify pore size distribution and interconnectivity. (Photo courtesy Oak Ridge National Laboratory)

Gas and oil deposits in shale have no place to hide from an Oak Ridge National Laboratory technique that provides an inside look at pores and reveals structural information potentially vital to the nation’s energy needs.

The research by scientists at the U.S. Department of Energy laboratory could clear the path to the more efficient extraction of gas and oil from shale, environmentally benign and efficient energy production from coal, and perhaps viable carbon dioxide sequestration technologies, according to Yuri Melnichenko, an instrument scientist at ORNL’s High Flux Isotope Reactor. [Read more…]