Clemson University team’s graphene-enhanced aluminum-ion batteries outperform lithium-ion ones

Oct 19, 2017

Clemson’s graphene-enhanced aluminum ion batteries outperform Li-ion ones image

Researchers at Clemson University in the U.S have shown that replacing lithium with aluminum and graphene may be key for next-gen batteries.

Aluminum is regarded as non-toxic and much more plentiful than the lithium currently in widespread use (and cheaper). Aluminum also transfers energy more efficiently. Inside a battery, the element — lithium or aluminum — gives up some of its electrons, which flow through external wires to power a device.

Because of their atomic structure, lithium ions can only provide one electron at a time; aluminum can give three at a time. That, the team says, is the real point of the switch.
Still, aluminum ion batteries designed by other researchers have not performed as well as lithium ion batteries.

The Clemson team describes how they were able to get aluminum ion to perform better than previously tested aluminum ion batteries. “The problem isn’t that aluminum ions are deficient,” said a graduate student at the Clemson Nanomaterials Institute and the first author of the Nano Energy paper. 

It’s that unlike lithium ions that have been around for a while, we do not know much about how aluminum ions behave inside the battery.”

Material Matters

The electrode in a battery is like a bucket and the electrical charge is like sand inside the bucket. If the sand starts to flow out, the speed at which it flows is the current. The greater the speed (the larger the current) the quicker the bucket is empty and the sooner the battery goes flat. The more sand you store in the bucket, the longer the current lasts.

The Clemson team seems to have found a way to pack more sand in the bucket and used tools to confirm the bucket was full. Their new battery technology uses aluminum foil and few-layer graphene as the electrode to store electrical charge from aluminum ions present in the electrolyte.

“We knew that aluminum ions could be stored inside few-layer graphene,” the team said. “But the ions need to be packed efficiently to increase the battery capacity. The arrangement of aluminum ions inside graphene is critical for better battery performance.”

“These aluminum batteries can last more than 10,000 cycles without any performance loss,” the researchers said. “Our hope is to make aluminum batteries with higher energy to ultimately displace lithium-ion technology.”
The next step toward a commercially viable aluminum ion battery is lowering the cost. Although aluminum is relatively inexpensive, the electrolytes are pricey.

Source:  Clemson

U of South Carolina – Clemson: Research Could Usher in Next Generation of Batteries, Fuel Cells

Nano fuel cells c2cs35307e-f1Scientists from South Carolina’s leading public universities–the University of South Carolina and Clemson University–have made a discovery that could dramatically improve the efficiency of batteries and fuel cells.

The research, which is published in the journal Nature Communications, involves improving the transport of oxygen ions, a key component in converting chemical reactions into electricity. The team studied a well-known material, gadolinium doped ceria (GDC), which transports oxygen ions and is currently in use as a solid oxide fuel cell electrolyte. Through the use of additives and a “smart” chemical reaction, they demonstrated a greatly enhanced conductivity in GDC. The result is a faster and more efficient conversion into electricity.

“This breakthrough will pave the path to fabricate next generation energy conversion and storage devices with significantly enhanced performance, increasing energy efficiency and making energy environmentally benign and sustainable,” said Fanglin (Frank) Chen, a mechanical engineering professor at the University of South Carolina.

“The origin of the low grain boundary conductivity is known to be segregation of gadolinium (Gd) in the grain boundary which leads to a built-in charge at the interface referred to as the space charge effect,” Chen said. “This built in charge serves as a barrier for ion transport at the interface. The challenge is how to effectively avoid the segregation of Gd in the grain boundary. The grain boundary is extremely narrow, on the order of a few nano-meters. Therefore, it is extremely difficult to characterize and rationally control the amount of Gd in such a narrow region.”

“In order to make ‘clean’ grain boundaries and avoid the segregation of Gd at the interface we have added an electronic conductor cobalt iron spinel (CFO), resulting in a composite structure,” said Kyle Brinkman, a professor at Clemson University and co-author of the work. “The CFO reacts with the excess Gd present in the grain boundary of GDC to form a third phase. It was found that this new phase could also serve as an excellent oxygen ionic conductor. We further investigated the atomic microstructure around the grain boundary through a series of high resolution characterization techniques and found that Gd segregation in the grain boundary had been eliminated, leading to dramatic improvement in the grain boundary oxygen ionic conductivity of GDC.”

The improved oxygen ionic conductivity of GDC has been demonstrated in an oxygen permeation experiment where the elevated oxygen ion transport was used to separate pure oxygen from air at elevated temperatures. The approach of targeting emergent phases resulting in clean interfaces can be applied to a number of essential materials for energy conversion and storage devices used in handheld electronics, vehicles, and power plants, making them more cost-effective, efficient and environmentally friendly.

Currently, ceramic composites consisting of ionic and electronic conductive components like those in this study are under consideration for membrane separation devices that provide oxygen for enhanced conversion of coal and natural gas, as well as for membrane reactors used in natural gas conversion and recovery.

Story Source:

The above story is based on materials provided by University of South Carolina. Note: Materials may be edited for content and length.

New technology could open doors to next generation of high-speed gadgets

1-Clemson untitledCLEMSON — Two Clemson University researchers have developed a new technology that could enable gadgets ranging from computers to cell phones to run faster by transmitting information with light instead of electrical current.

In their recent breakthrough, Ramakrishna Podila and Apparao Rao have overcome one of the biggest challenges in creating affordable light-based gadgets. They said they discovered an all-carbon based optical diode that transmits light in one direction. It’s a critical advance because diodes are the basic building blocks for all gadgets.

With optical diodes, light-based gadgets would be able to more quickly perform the logic operations that make it possible to do all the things that make devices useful, whether it’s telling time or updating a Facebook status.

“This could open doors to the next generation of high-speed gadgets,” said Podila, an assistant research professor of physics.

1-Clemson untitled

Information in electronics is typically conveyed by transmitting electrons over tiny distances through copper wires laid on top of silicon chips. The idea of using light in computing has been around for decades, but developing the logic components that are affordable has been a challenge.

One of the biggest hurdles has been figuring out how to transmit light in one direction, while prohibiting light from the other direction, said Rao who is the R. A. Bowen professor of physics at Clemson.

“It sounds easy, but it’s scientifically very difficult,” he said.

Podila and Rao are advancing the technology with graphene, a pure carbon sheet that is remarkably strong even though it is only an atom thick.

The graphene sheet is placed on fullerene film, which is also made of carbon. “The graphene-fullerene sandwich structure acquires an unusual optical property—it turns into a one-way street for light,” Podila said.

Light can pass through the sandwich structure only when it comes from the graphene side. Light cannot be transmitted when comes from the fullerene side. “The graphene-fullerene sandwich structure is key for allowing one-way transmission of light,” Rao said “Our technology creates optical diodes in an easy and scalable fashion, and that leads to affordability.” The team did its work at the Clemson Nanomaterials Center in collaboration with the Raman Research Institute and the Sri Sathya Sai Institute for Higher Learning, India. Their findings were published in a Nano Letters article (Nano Letters, 13, 5771) with Podila serving as a corresponding author.

“Ours is an extremely simple device,” Podila said. “It is also compact and has the potential for large bandwidth, which makes it cost-effective for large-scale integration in photonic circuits.” The next step in the research is to modify graphene with various substances known as dopants, Rao said.

“We’ll try doping graphene with nitrogen, or maybe boron,” he said. “We’ll try different elements that are in the neighborhood of carbon in the periodic table and see how to improve the device’s performance.” It will likely take another phase of research and 10 or more years to make the technology widely available in off-the-shelf products, Rao said. “We’re looking for industry partners to take this research to the next level,” he said.

Mark Leising, chair of Clemson’s Department of Physics and Astronomy, said the work that Podila, Rao and their team are doing is on the cutting edge of nanotechnology. “Their research could improve the speed and security of data processing, and ease Internet traffic,” Leising said.

“It is heartening to see three international teams come together under Clemson’s lead to make this discovery. It’s happening right here at Clemson’s Physics and Astronomy Department and it could have meaningful, tangible effects around the globe.”