From COSMOS Magazine: “Race for potassium batteries hots up”

From COSMOS Magazine

13 May 2019
Phil Dooley

Research aims to solve problems arising with potential lithium rival.

Mounds of potassium waste from a salt mine in the town of Soligorsk, some 140 kilometres south from Minsk, in Belarus. Credit: SERGEI GAPON/AFP/Getty Images

Battery technology based on potassium could be the key to storing energy from renewables, according to a team of scientists from Wollongong University in Australia.

Currently lithium ion batteries are widely used because of their high energy density, but, because lithium is a relatively rare element, mining costs make them expensive.

As an alternative, potassium, which is one of the Earth’s most abundant elements, could become the basis for a large-scale power storage, says Zaiping Guo, one of the authors of a review paper in the journal Science Advances.

“Potassium is a rechargeable with huge potential, and has theoretically cheaper performance compared with lithium,” she says.

The global market for lithium batteries was worth $25 billion in 2017, driven by technologies that require low-weight energy storage, such as electric cars and electronic devices.

Potassium batteries are unlikely to reach the same energy density, because it is a heavier atom than lithium. However, it may succeed as a stationary large-scale storage method, coupled to intermittent renewable energy sources.

“For a more sustainable society we need energy storage devices,” Guo says.

“Compared with other storage options, such as super-capacitors or fuel cells, batteries are the most mature and easy to apply.”

Even so, she estimates it will take 10 to 20 years before the potassium-based technology matures enough to close the gap on lithium.

One of the major obstacles in creating an efficient potassium battery is the sluggish movement of large potassium ions through a solid electrode.

Secondly, as the ions enter the electrode during the electrical reactions, their size causes the electrodes to swell, then shrink again as the reverse reaction occurs when the battery finishes charging and starts to discharge.

It’s a challenge to develop an electrode material that can survive such repeated size change, but the team points out that nanotechnology could provide answers.

Clusters of nanoparticles similar to bunches of grapes can withstand repeated size changes. Nanostructures with high surface areas could also remove the need for the potassium ions to penetrate far in to the electrode: various researchers have investigated [NCBI] structures with large surface areas.

The structures have names such as nanotubes, nanofibres and even nanoroses.

To complicate the situation, potassium is prone to other, less welcome reactions, which the nanomaterials can actually promote. However, careful choice of a material for the electrodes can help control these unwanted processes, for example by adding atoms of fluorine, oxygen, boron or sulfur to the carbon mix.

Unwanted reactions are also a problem in the electrolyte – the conductive solution that allows potassium ions to flow between the two electrodes. For example, the potassium can deposit into intricate tree-shaped crystals called dendrites, which can cause a short-circuit within the battery.

Guo points out that choice of solvent and use of additives can address these reactions. But it’s a balance, because the most effective solvents are organic, and therefore flammable. Alongside the tendency of potassium batteries to get hot, this is a safety issue that needs consideration.

The advent of powerful computer modeling will help solve such issues, say the authors. Although there a number of obstacles, they conclude that potassium battery technology is “emerging as a great candidate for large-scale energy storage”.

See the full article here .

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From BNL: “Scientists Design Promising New Cathode for Sodium-based Batteries” 2017

Brookhaven Lab

July 20, 2017
Stephanie Kossman
skossman

Xiao-Qing Yang (left) and Enyuan Hu (center) of Brookhaven’s Chemistry Department, pictured with beamline physicist Eli Stavitski (right) at the ISS beamline at NSLS-II.

Scientists have designed a new type of cathode that could make the mass production of sodium batteries more feasible. Batteries based on plentiful and low-cost sodium are of great interest to both scientists and industry as they could facilitate a more cost-efficient production process for grid-scale energy storage systems, consumer electronics and electric vehicles. The discovery was a collaborative effort between researchers at the Institute of Chemistry (IOC) of Chinese Academy of Sciences (CAS) and the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory.

Lithium batteries are commonly found in consumer electronics such as smartphones and laptop computers, but in recent years, the electric vehicle industry also began using lithium batteries, significantly increasing the demand on existing lithium resources.

“Just last year, the price of lithium carbonate tripled, because the Chinese electric vehicle market started booming,” said Xiao-Qing Yang, a physicist at the Chemistry Division of Brookhaven Lab and the lead Brookhaven researcher on this study.

In addition, the development of new electrical grids that incorporate renewable energy sources like wind and solar is also driving the need for new battery chemistries. Because these energy sources are not always available, grid-scale energy storage systems are needed to store the excess energy produced when the sun is shining and the wind is blowing.

Scientists have been searching for new battery chemistries using materials that are more readily available than lithium. Sodium is one of the most desirable options for researchers because it exists nearly everywhere and is far less toxic to humans than lithium.

But sodium poses major challenges when incorporated into a traditional battery design. For example, a typical battery’s cathode is made up of metal and oxygen ions arranged in layers. When exposed to air, the metals in a sodium battery’s cathode can be oxidized, decreasing the performance of the battery or even rendering it completely inactive.

The researchers at IOC of CAS and Jiangxi Normal University sought to resolve this issue by substituting different types of metals in the cathode and increasing the space between these metals. Then, using the Inner-Shell Spectroscopy (ISS) beamline at Brookhaven’s National Synchrotron Light Source II (NSLS-II)—a DOE Office of Science User Facility—Brookhaven’s researchers compared the structures of battery materials with unsubstituted materials to these new battery materials with substitute metals.

“We use the beamline to determine how metals in the cathode material change oxidation states and how it correlates with the efficiency and lifetime of the battery’s structure,” says Eli Stavitski, a physicist at the ISS beamline.”

The ISS beamline was the first operational x-ray spectroscopy beamline at NSLS-II. Here, researchers shine an ultra-bright x-ray beam through materials to observe how light is absorbed or reemitted. These observations allow researchers to study the structure of different materials, including their chemical and electronic states.

The ISS beamline, which is specifically designed for high-speed experiments, allowed the researchers to measure real-time changes in the battery during the charge-discharge processes. Based on their observations made at the beamline, Brookhaven’s team discovered that oxidation was suppressed in the sodium batteries with substituted metals, indicating the newly designed sodium batteries were stable when exposed to air. This is a major step forward in enabling future mass production of sodium batteries.

The researchers say this study[JACS] is the first of many that will use the ISS beamline at NSLS-II to advance the study of batteries.

This study was supported by several Chinese research organizations, including the National Key R&D Program of China. The work at Brookhaven National Laboratory was supported by DOE’s Office of Energy Efficiency and Renewable Energy, the Vehicle Technology Office under Advanced Battery Material Research (BMR). DOE’s Office of Science (BES) also supports operations at NSLS-II.

See the full article here .

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One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

From UC Riverside: “Researchers Create Next Generation of High-Performance Lithium-Ion Batteries”

UC Riverside

December 21, 2017
Richard Chang
(951) 827-5893
rchang@ucr.edu

Cengiz Ozkan and Mihri Ozkan are developing the next generation of batteries. [Others not named]

Researchers at the University of California, Riverside’s Bourns College of Engineering have developed a technique to create high performance lithium-ion batteries utilizing sulfur and silicon electrodes. The batteries will extend the range of electric vehicles and plug-in hybrid electric vehicles, while also providing more power with fewer charges to personal electronic devices such as cell phones and laptops.

The findings were published in an article titled, Advanced Sulfur-Silicon Full Cell Architecture for Lithium Ion Batteries, in the journal, Nature Scientific Reports. Cengiz Ozkan, professor of mechanical engineering, and Mihri Ozkan, professor of electrical and computer engineering, led the project.

“The demand for renewable energy has pushed the need for higher-performance batteries,” Cengiz Ozkan said.

As a result, researchers have turned toward new lithium-ion battery systems with higher capacities. Silicon is the most promising anode candidate, storing up to 10 times the capacity of graphite anodes. Sulfur is the most promising cathode candidate, with up to six times the capacity of cathodes. Sulfur-silicon lithium-ion full cells, utilizing silicon as the anode and sulfur as the cathode, are one of the highest-capacity potential systems that have been studied. However, the practice of building sulfur-silicon full cells is challenged by the limitations in materials and equipment.

“This has limited the amount and extent of research done on the sulfur-silicon full cells, which is why the team proposed and tested a new approach to incorporate lithium into a sulfur-silicon full cell,” Mihri Ozkan said.

To create the sulfur-silicon full cells (SSFC) with the new architecture, the team added a piece of lithium foil into the traditional full-cell architecture, while enabling contact between the lithium foil and the current collector. This allows the lithium foil to integrate into the system while the battery is being cycled, allowing for control over the amount of lithium inserted.

“In order to bring together sulfur and silicon electrodes, it is necessary to explore alternative methods of introducing lithium to the system,” said Jeffrey Bell, a UC Riverside graduate student who worked on the project. “We believe that we’ve provided one such solution that will further advance research on sulfur-silicon full cells.”

“In half cells, pure lithium is used as the anode, which raises safety concerns such as dendrite formation and lithium corrosion. In a full cell, silicon is used as the anode instead, which mitigates the safety issues created by pure lithium anodes, while maintaining the desired high-battery capacity,” added graduate student Rachel Ye.

This research is the latest in a series of projects led by the Ozkans to create lithium-ion battery materials and architectures from abundant resources and environmentally friendly materials. Previous research has focused on developing and testing anodes from glass bottles, portabella mushrooms, sand, and diatomaceous (fossil-rich) earth.

In addition to Bell and Ye, other research contributors include graduate students Daisy Patino and Kazi Ahmed. Funding came from UCR and Vantage Advanced Technologies. The university’s Office of Technology Commercialization has filed a patent application for the inventions.

See the full article here .

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The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From Stanford: “A Stanford battery based on sodium may offer more cost-effective storage than lithium”

Stanford University

October 9, 2017
Tom Abate
tabate@stanford.edu

Stanford researchers are developing a sodium ion battery based on a compound related to table salt. (Image credit: Getty Images)

As a warming world moves from fossil fuels toward renewable solar and wind energy, industrial forecasts predict an insatiable need for battery farms to store power and provide electricity when the sky is dark and the air is still. Against that backdrop, Stanford researchers have developed a sodium-based battery that can store the same amount of energy as a state-of-the-art lithium ion, at substantially lower cost.

Chemical engineer Zhenan Bao and her faculty collaborators, materials scientists Yi Cui and William Chueh, aren’t the first researchers to design a sodium ion battery. But they believe the approach they describe in an Oct. 9 Nature Energy paper has the price and performance characteristics to create a sodium ion battery costing less than 80 percent of a lithium ion battery with the same storage capacity.

“Nothing may ever surpass lithium in performance,” Bao said. “But lithium is so rare and costly that we need to develop high-performance but low-cost batteries based on abundant elements like sodium.”

With materials constituting about one-quarter of a battery’s price, the cost of lithium – about $15,000 a ton to mine and refine – looms large. That’s why the Stanford team is basing its battery on widely available sodium-based electrode material that costs just $150 a ton.

This sodium-based electrode has a chemical makeup common to all salts: It has a positively charged ion – sodium – joined to a negatively charged ion. In table salt, chloride is the positive partner, but in the Stanford battery a sodium ion binds to a compound known as myo-inositol. Unlike the chloride in table salt, myo-inositol is not a household word. But it is a household product, found in baby formula and derived from rice bran or from a liquid byproduct of the process used to mill corn. Crucial to the idea of lowering the cost of battery materials, myo-inositol is an abundant organic compound familiar to industry.

Making it work

The sodium salt makes up the cathode, which is the pole of the battery that stores electrons. The battery’s internal chemistry shuttles those electrons toward the anode, which in this case is made up of phosphorous. The more efficiently the cathode shuttles those electrons toward and backward versus the anode, the better the battery works. For this prototype, postdoctoral scholar Min Ah Lee and the Stanford team improved how sodium and myo-inositol enable that electron flow, significantly boosting the performance of this sodium ion battery over previous attempts. The researchers focused mainly on the favorable cost-performance comparisons between their sodium ion battery and state of the art lithium. In the future they’ll have to look at volumetric energy density – how big must a sodium ion battery be to store the same energy as a lithium ion system.

In addition, the team optimized their battery’s charge-recharge cycle – how efficiently the battery stores electricity coming in from a rooftop solar array, for instance, and how effectively it delivers such stored power to, say, run the house lights at night. To better understand the atomic-level forces at play during this process, postdoctoral scholar Jihyun Hong and graduate student Kipil Lim worked with Chueh and Michael Toney, a scientist with the SLAC National Accelerator Laboratory. They studied precisely how the sodium ions attach and detach from the cathode, an insight that helped improve their overall battery design and performance.

The Stanford researchers believe their Nature Energy paper demonstrates that sodium-based batteries can be cost-effective alternatives to lithium-based batteries. Having already optimized the cathode and charging cycle, the researchers plan to focus next on tweaking the anode of their sodium ion battery.

“This is already a good design, but we are confident that it can be improved by further optimizing the phosphorus anode,” said Cui.

Other members of the team included Stanford researchers Jeffrey Lopez, Yongming Sun and Dawei Feng. The work was funded by the U.S. Department of Energy’s Advanced Battery Materials Research (BMR) Program. X-ray measurements were carried out at the Stanford Synchrotron Radiation Laboratory (SSRL), a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.

See the full article here .

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Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

From BNL: “Slicing Through Materials with a New X-ray Imaging Technique”

Brookhaven Lab

August 12, 2016
Chelsea Whyte,
cwhyte@bnl.gov
(631) 344-8671

Peter Genzer,
genzer@bnl.gov
(631) 344-3174

Images reveal battery materials’ chemical reactions in five dimensions – 3D space plus time and energy

The chemical phase within the battery evolves as the charging time increases. The cut-away views reveal a change from anisotropic to isotropic phase boundary motion. No image credit

Researchers at the U.S. Department of Energy’s Brookhaven National Laboratory have created a new imaging technique that allows scientists to probe the internal makeup of a battery during charging and discharging using different x-ray energies while rotating the battery cell. The technique produces a three-dimensional chemical map and lets the scientists track chemical reactions in the battery over time in working conditions. Their work is published in the August 12 issue of Nature Communications.

Getting an accurate image of the activity inside a battery as it charges and discharges is a difficult task. Often even x-ray images don’t provide researchers with enough information about the internal chemical changes in a battery material because two-dimensional images can’t separate out one layer from the next. Imagine taking an x-ray image of a multi-story office building from above. You’d see desks and chairs on top of one another, several floors of office spaces blending into one picture. But it would be difficult to know the exact layout of any one floor, let alone to track where one person moved throughout the day.

Getting an accurate image of the activity inside a battery as it charges and discharges is a difficult task. Often even x-ray images don’t provide researchers with enough information about the internal chemical changes in a battery material because two-dimensional images can’t separate out one layer from the next. Imagine taking an x-ray image of a multi-story office building from above. You’d see desks and chairs on top of one another, several floors of office spaces blending into one picture. But it would be difficult to know the exact layout of any one floor, let alone to track where one person moved throughout the day.

“It’s very challenging to carry out in-depth study of in situ energy materials, which requires accurately tracking chemical phase evolution in 3D and correlating it to electrochemical performance,” said Jun Wang, a physicist at the National Synchrotron Light Source II, who led the research.

Using a working lithium-ion battery, Wang and her team tracked the phase evolution of the lithium iron phosphate within the electrode as the battery charged. They combined tomography (a kind of x-ray imaging technique that displays the 3D structure of an object) with X-ray Absorption Near Edge Structure (XANES) spectroscopy (which is sensitive to chemical and local electronic changes). The result was a “five dimensional” image of the battery operating: a full three-dimensional image over time and at different x-ray energies.

To make this chemical map in 3D, they scanned the battery cell at a range of energies that included the “x-ray absorption edge” of the element of interest inside the electrode, rotating the sample a full 180 degrees at each x-ray energy, and repeating this procedure at different stages as the battery was charging. With this method, each three-dimensional pixel—called a voxel—produces a spectrum that is like a chemical-specific “fingerprint” that identifies the chemical and its oxidation state in the position represented by that voxel. Fitting together the fingerprints for all voxels generates a chemical map in 3D.

The scientists found that, during charging, the lithium iron phosphate transforms into iron phosphate, but not at the same rate throughout the battery. When the battery is in the early stage of charging, this chemical evolution occurs in only certain directions. But as the battery becomes more highly charged, the evolution proceeds in all directions over the entire material.

“Were these images to have been taken with a standard two-dimensional method, we wouldn’t have been able to see these changes,” Wang said.

“Our unprecedented ability to directly observe how the phase transformation happens in 3D reveals accurately if there is a new or intermediate phase during the phase transformation process. This method gives us precise insight into what is happening inside the battery electrode and clarifies previous ambiguities about the mechanism of phase transformation,” Wang said.

Wang said modeling will help the team explore the way the spread of the phase change occurs and how the strain on the materials affects this process.

This work was completed at the now-closed National Synchrotron Light Source (NSLS), which housed a transmission x-ray microscope (TXM) developed by Wang using DOE funds made available through American Recovery and Reinvestment Act of 2009. This TXM instrument will be relocated to Brookhaven’s new light source, NSLS-II, which produces x-rays 10,000 times brighter than its predecessor. Both NSLS and NSLS-II are DOE Office of Science User Facilities.

“At NSLS-II, this work can be done incredibly efficiently,” she said. “The stability of the beam lends itself to good tomography, and the flux is so high that we can take images more quickly and catch even faster reactions.”

This work was supported by the DOE Office of Science.

See the full article here .

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One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

From SLAC: “Stanford-led team reveals nanoscale secrets of rechargeable batteries”

SLAC Lab

August 4, 2016
Andrew Myers

Artist’s rendition shows lithium-ion battery particles under the illumination of a finely focused X-ray beam. (Image credit: Courtesy Chueh Lab)

An interdisciplinary team has developed a way to track how particles charge and discharge at the nanoscale, an advance that will lead to better batteries for all sorts of mobile applications.

Better batteries that charge quickly and last a long time are a brass ring for engineers. But despite decades of research and innovation, a fundamental understanding of exactly how batteries work at the smallest of scales has remained elusive.

In a paper published this week in the journal Science, a team led by William Chueh, an assistant professor of materials science and engineering at Stanford and a faculty scientist at the Department of Energy’s SLAC National Accelerator Laboratory, has devised a way to peer as never before into the electrochemical reaction that fuels the most common rechargeable cell in use today: the lithium-ion battery.

By visualizing the fundamental building blocks of batteries – small particles typically measuring less than 1/100th of a human hair in size – the team members have illuminated a process that is far more complex than once thought. Both the method they developed to observe the battery in real time and their improved understanding of the electrochemistry could have far-reaching implications for battery design, management and beyond.

“It gives us fundamental insights into how batteries work,” said Jongwoo Lim, a co-lead author of the paper and post-doctoral researcher at the Stanford Institute for Materials & Energy Sciences at SLAC. “Previously, most studies investigated the average behavior of the whole battery. Now, we can see and understand how individual battery particles charge and discharge.”

The heart of a battery

At the heart of every lithium-ion battery is a simple chemical reaction in which positively charged lithium ions nestle in the lattice-like structure of a crystal electrode as the battery is discharging, receiving negatively charged electrons in the process. In reversing the reaction by removing electrons, the ions are freed and the battery is charged.

An interdisciplinary research team has developed a new way to track how battery particles charge and discharge. Greatly magnified nanoscale particles are shown here charging (red to green) and discharging (green to red). The animation shows regions of faster and slower charge. (Image credit: SLAC National Accelerator Laboratory)

These basic processes – known as lithiation (discharge) and delithiation (charge) – are hampered by an electrochemical Achilles heel. Rarely do the ions insert uniformly across the surface of the particles. Instead, certain areas take on more ions, and others fewer. These inconsistencies eventually lead to mechanical stress as areas of the crystal lattice become overburdened with ions and develop tiny fractures, sapping battery performance and shortening battery life.

“Lithiation and delithiation should be homogenous and uniform,” said Yiyang Li, a doctoral candidate in Chueh’s lab and co-lead author of the paper. “In reality, however, they’re very non-uniform. In our better understanding of the process, this paper lays out a path toward suppressing the phenomenon.”

For researchers hoping to improve batteries, like Chueh and his team, counteracting these detrimental forces could lead to batteries that charge faster and more fully, lasting much longer than today’s models.

This study visualizes the charge/discharge reaction in real-time – something scientists refer to as operando – at fine detail and scale. The team utilized brilliant X-rays and cutting-edge microscopes at Lawrence Berkeley National Laboratory’s Advanced Light Source.

LBL ALS

“The phenomenon revealed by this technique, I thought would never be visualized in my lifetime. It’s quite game-changing in the battery field,” said Martin Bazant, a professor of chemical engineering and of mathematics at MIT who led the theoretical aspect of the study.

Chueh and his team fashioned a transparent battery using the same active materials as ones found in smartphones and electric vehicles. It was designed and fabricated in collaboration with Hummingbird Scientific. It consists of two very thin, transparent silicon nitride “windows.” The battery electrode, made of a single layer of lithium iron phosphate nanoparticles, sits on the membrane inside the gap between the two windows. A salty fluid, known as an electrolyte, flows in the gap to deliver the lithium ions to the nanoparticles.

“This was a very, very small battery, holding ten billion times less charge than a smartphone battery,” Chueh said. “But it allows us a clear view of what’s happening at the nanoscale.”

Significant advances

In their study, the researchers discovered that the charging process (delithiation) is significantly less uniform than discharge (lithiation). Intriguingly, the researchers also found that faster charging improves uniformity, which could lead to new and better battery designs and power management strategies.

“The improved uniformity lowers the damaging mechanical stress on the electrodes and improves battery cyclability,” Chueh said. “Beyond batteries, this work could have far-reaching impact on many other electrochemical materials.” He pointed to catalysts, memory devices, and so-called smart glass, which transitions from translucent to transparent when electrically charged.

In addition to the scientific knowledge gained, the other significant advancement from the study is the X-ray microscopy technique itself, which was developed in collaboration with Berkeley Lab Advanced Light Source scientists Young-sang Yu, David Shapiro, and Tolek Tyliszczak. The microscope, which is housed at the Advanced Light Source, could affect energy research across the board by revealing never-before-seen dynamics at the nanoscale.

“What we’ve learned here is not just how to make a better battery, but offers us a profound new window on the science of electrochemical reactions at the nanoscale,” Bazant said.

Funding for this work was provided in part by the U.S. Department of Energy, Office of Basic Energy Sciences, and by the Ford-Stanford Alliance. Bazant was a visiting professor at Stanford and was supported by the Global Climate and Energy Project.

See the full article here .

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SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

From ORNL: “ORNL researchers use neutrons to gain insight into battery inefficiency”

Oak Ridge National Laboratory

January 19, 2016
Dawn Levy, Communications
levyd@ornl.gov
865.576.6448

In a Fluid Interface Reactions, Structures and Transport Center project to probe a battery’s atomic activity during its first charging cycle, Robert Sacci and colleagues used the Spallation Neutron Source’s vibrational spectrometer to gain chemical information. Image credit: Oak Ridge National Laboratory, U.S. Dept. of Energy; photographer Genevieve Martin.

Rechargeable batteries power everything from electric vehicles to wearable gadgets, but obstacles limit the creation of sleeker, longer-lasting and more efficient power sources. Batteries produce electricity when charged atoms, known as ions, move in a circuit from a positive end (anode) to a negative end (cathode) through a facilitating mix of molecules called an electrolyte.

Scientists at the Department of Energy’s Oak Ridge National Laboratory are improving the lifetimes of rechargeable batteries that run on lithium, a small atom that can pack tightly into graphite anode materials. The valuable ions are depleted as a battery charges, and they are also lost to the formation of a thin coating on a battery’s anode during initial charging. ORNL researchers used two of the most powerful neutron science facilities in the world to try to understand the dynamics behind this phenomenon.

In a paper published in the Journal of Physical Chemistry C, the ORNL researchers focused on the spontaneous growth of the thin coating, called the solid-electrolyte interphase (SEI). This nanoscale coating protects and stabilizes the new battery, but it comes at a cost. The electrolyte, a mixture of molecules composed of hydrogen, carbon, lithium and oxygen, is forced to break down to form this film.

“The big picture is to increase the amount of lithium we can put into a battery,” said Robert Sacci, lead author and Materials Science and Technology Division scientist. “When you develop a battery, you put in excess lithium because a lot of that lithium gets eaten up or taken away from usability to form this thin film.”

Sacci and colleagues used beams of subatomic particles called neutrons to delve into a battery’s atomic reactivity during its first charging cycle. Neutrons were necessary because they can easily enter three-dimensional structures and are sensitive to changes in hydrogen concentration, a major component of electrolytes.

ORNL researchers targeted anode samples with neutrons from the Spallation Neutron Source (SNS), the world’s most intense pulsed beam, and the High Flux Isotope Reactor (HFIR), the highest continuous-beam research reactor in the United States. They tracked the scattered paths of the neutrons after the beams penetrated the material, creating a constantly updating map of the sample’s molecular dynamics.

ORNL Spallation Neutron Source

ORNL High Flux Isotope Reactor

Neutron scattering is key to understanding battery activity on the atomic scale. While the diffracted beams of neutrons would appear to be a jumbled mess to most—like lights dancing off a disco ball in all directions—skilled scientists use these scattering signals to calculate chemical and structural changes while the SEI layer develops.

Is battery film friend or foe?

Once the SEI layer forms, it buffers degradation of the electrolyte and prevents a dangerous buildup of metal deposits on the lithiated-graphite anode, increasing a battery’s life cycle.

Sacci and his team wondered if a pre-made film could protect the anode while minimizing the consumption of lithium ions.

The ORNL scientists incorporated lithium atoms into vacancies within graphite through grinding at high force. The result was a powdery, charged anode material that they then dipped into an electrolyte solution.

A thin film formed around each lithiated-graphite particle, encapsulating it. At this point, the scientists were ready to subject samples to neutron scattering tests to gain a fresh perspective into how an SEI layer generates during initial charging of a lithium-ion battery.

Researchers used SNS’s vibrational spectrometer, VISION, to gain chemical information about the SEI layer. HFIR allowed the ORNL scientists to use small-angle neutron scattering (SANS) techniques to map the thin film’s structure and chart new information about its formation.

“With VISION, we can measure the vibrations of atoms, which tell us how they are bound within molecules, and with SANS, a scattering instrument at HFIR, you’re looking more or less at how big the particles are and how they are arranged,” Sacci said.

After exploring the lithiated-graphite anode material, Sacci and his fellow energy researchers now understand the chemical process by which the thin protective layer generates on the anode.

“We were able to definitely say, yes a polymer formed, the particles appeared bigger—which means a layer grew on them—and they were more interconnected,” said Sacci.

“The advantage of forming this polymeric solid-electrolyte interface prior to battery assembly is that the battery would last longer, and that it’s a good stepping stone to giving us clues into how to design these artificial interfaces.”

This research was supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy Office of Science. Work was performed at the Spallation Neutron Source and the High Flux Isotope Reactor, DOE Office of Science User Facilities at ORNL.

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, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/.—by Ashanti B. Washington

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ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

From COSMOS: “Batteries – a guide to the future”

COSMOS

14 Dec 2015
Viviane Richter

Batteries that store renewable energy are essential for the Paris climate agreement to work. Viviane Richter describes the rechargeable batteries that could make it happen.

Turning solar and wind electricity into a 24/7 power source as reliable as coal. Eliminating the “range anxiety” that stops people switching from petrol to electric cars. Stopping the irritation of flat smartphones or laptops.

Those are just a few of the advantages that affordable long-lived rechargeable batteries, capable of delivering a sustained high-powered output over weeks instead of days could offer.

According to the experts, we have the technology. What we don’t have is the magic mix of affordability, lightness and power delivery in a single battery. Instead, rechargeable batteries are diversifying, spawning a range of storage tools, each best suited to a particular niche. Here we meet the five frontrunners.

Reigning champion — the lithium ion battery

Tesla Powerwall Credit: Tesla

Potential use: Almost everything – devices, electric cars, household renewable energy storage.
Advantages: Proven, mature technology.
Disadvantages: Most gains in energy storage have already been made. Some safety concerns.

Lithium ion battery are the reigning champions when it comes to energy density — the amount of electric charge stored by weight.

And the technology is well proven. Even sexy. Witness the sleek Tesla Powerwall, a large lithium ion battery pack that, connected to solar panels, could enable a household to disconnect from the grid. Meanwhile, Tesla CEO Elon Musk says the company’s Gigafactory in Nevada will produce enough lithium ion batteries to fit half million electric cars a year at a third of current costs.

You can think of the lithium ion battery as a tiny water tower. When you charge your phone, electrons are pumped up into a storage tank called the “anode”, where they’re captured by lithium ions. Turning on your phone is like turning on the tap: electrons come flooding out of the lithium, and through your phone’s circuitry – before being collected in a receiver tank called the “cathode”.

At the same time, the lithium ions cross the battery directly to reach the cathode. Here, electrons and lithium ion recombine – but as a spent force. Charging the battery re-energises the pair by pumping them back up to the anode.

But there are safety concerns. Solvents in lithium ion batteries, such as diethyl carbonate, are inflammable and sometimes things go wrong. For example, in 2013 lithium batteries caused a fire on a Boeing’s 787 Dreamliner at Boston’s Logan International Airport, grounding the fleet.

Such mishaps could be avoided if a new technology developed by Chunsheng Wang and colleagues at the University of Maryland in Baltimore pans out – a non-flammable salt solvent that can carry lithium ions, creating a battery with the same power as a conventional lithium ion battery. By fine-tuning the chemistry the team thinks it can push the battery’s performance further. He published his development in Science in November

Still, the lithium ion battery won’t be the champion forever. When it comes to energy density, lithium ion batteries may be the best we’ve got, but the technology’s already been pushed “almost as far as it can go”, says Adam Best, a materials engineer at Commonwealth Scientific and Industrial Research Organisation in Melbourne.

Second-in-command — the lithium sulfur battery

A new all-solid lithium-sulfur battery developed by an Oak Ridge National Laboratory team led by Chengdu Liang has the potential to reduce cost, increase performance and improve safety compared with existing designs.Credit: Oak Ridge National Laboratory, U.S. Dept. of Energy

Potential use: Devices, electrical cars, household renewable energy storage.
Advantages: Potentially 5x more energy dense than lithium ion
Disadvantages: shorter lifespan than lithium ion batteries.

Lithium sulfur is the next battery we’ll see rolled out commercially, says Cameron Shearer, materials engineer at Flinders University in Adelaide. Otis Energy, a UK-based company, has announced that next year they will sell this type of battery for electric cars and solar energy storage. But they could soon be powering smartphones too.

Whereas conventional lithium ion batteries use a slab of graphite to capture lithium ions at the anode, this battery uses a lightweight slither of lithium itself. And at the cathode, the battery uses sulfur to soak up the spent lithium and electrons – again, a lighter option than the mixture of metals in a conventional lithium ion battery cathode.

Their lighter construction and favourable electrochemistry means that, at least on paper, a lithium sulfur battery can hold five times more electrons than lithium ion batteries, weight for weight – and at lower cost (sulfur is cheap).

But the lithium sulfur battery is not long-lived – the lithium and sulfur tend to react together and clog pores in the cathode, and the sulfur begins to decompose. One solution could be to wrap the battery in a thin protective polymer coat — this helps hold the sulfur together, according to work from chemists at the Toyota Research Institute of North America in Michigan published in Energy and Environmental Science in November.

Shearer is a strong supporter of lithium sulfur batteries, predicting their reliability and lifespan will match lithium ion batteries within 10 years.

Lives fast, dies young — the lithium air battery

Potential use: Devices, electric cars.
Advantages: Very light, and on paper 10x more energy dense than lithium ion.
Disadvantages: Very short lifespan (so far).

Rather than using sulfur to soak up lithium at its cathode, this battery uses oxygen from the air. When the battery is charged, the oxygen is exhaled again. As a result, these batteries are exceptionally light – on paper they could store 10 times more energy than a lithium ion battery of the same weight. That’s your smartphone powered for more than a week on one charge – or an electric car with range longer than a petrol car with a full tank.

“If you can make lithium-air work, you’ve pretty much got the most energy dense device available to man,” says Best.

Sadly, so far the lithium air battery’s lifespan is even worse than lithium sulfur’s. And for the same old reasons – clogged cathodes, in this case because the lithium reacts with other molecules in the air.

“It’s losing around 10 to 20 % [capacity] each time it’s cycled,” says Best. In October in Science, researchers at the University of Cambridge revealed a better type of lithium air battery. It contains a different anode that happily tolerates lithium hydroxide particles that form when lithium reacts with moisture in the air. But reaction with nitrogen still clogs the cathode.

We’re unlikely to see lithium air move from lab bench to the market any time soon. “It’s 10 to 20 years away, if that,” says Best.

Slow, chubby and cheap — the sodium ion battery

Potential use: devices, electric car, household renewable energy storage
Advantages: Lower cost than lithium ion.
Disadvantages: Lower performance than lithium ion.

Lithium has so far quenched our thirst for portable electronics, but demand for lithium is rising – an electric car battery requires about four kilograms. And lithium isn’t cheap, which will continue to push up the price of batteries as lithium becomes scarcer.

Enter the sodium ion battery. It works like a lithium ion battery but uses cheaper, more abundant sodium as its electron source. The drawback is that it is not as energy dense – sodium atoms are bigger and heavier than lithium.

For now, that takes it out the running for mobile applications such as electronic devices and electric cars, but not for solar energy storage, where cost is critical and size and weight less of an issue. Faradion, a UK-based company, and Aquion Energy, a US company, are already selling sodium ion batteries for these purposes.

And if lithium prices do spike? That could provide the incentive for mass manufacture of sodium ion batteries – they could be ready for use in phones and laptops, in perhaps as little as five years, according to some estimates.
The alien — the flow battery

Potential use: Storage of renewable energy.
Advantages: Cheap and reliable.
Disadvantages: Low energy density. Must be stationary because of the heavy liquids and pumps.

The flow battery promises to be the heavy-duty storage workhorse.

Flow batteries don’t use an anode or cathode – they store energy by shuttling electrons between two large tanks of liquid. In place of lithium, most flow batteries use vanadium. Where lithium ions need to latch on to an anode or cathode to store electrons, vanadium ions are stable in solution.

Flow batteries have a long lifetime as there is no solid anode or cathode to degrade. What’s more, it’s easy to increase capacity – simply feed in more solution.

Their drawback is low energy density. The ions need a lot of liquid to be stable and this liquid needs to be pumped around to keep the ions evenly distributed. That makes the battery heavy and big – the smallest are about the size of a bar fridge. You wouldn’t use one in an electric car, let alone a phone.

But at least one company, Australian firm Redflow, already sells flow batteries – for renewable energy storage at remote mine sites.

Home use is also not out of the question. “The Tesla Powerwall is made to show off,” says Cameron Shearer of Flinders University in Adelaide. “You’d have a flow battery hidden in your wall.”

How we’re designing new batteries has changed. “We’re moving from a sort of cottage industry to a much more sophisticated atomic design of materials,” says Anthony Vassallo, battery chemist at the University of Sydney. High-resolution microscopy techniques are enabling scientists to custom-design anodes, cathodes and other battery parts from the atoms up. Within five to 10 years, he estimates, nano-engineered battery components will be mass produced on 3D printers.

Perhaps these could be the enabling technologies that springboard advanced batteries such as lithium air out of the lab and into real world renewable energy storage.

See the full article here .

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From EPFL: “An innovative response to the challenge of storing renewable energy”

Ecole Polytechnique Federale Lausanne

26.10.15
Emmanuel Barraud

Inside the Container. Alain Herzog/EPFL

A system for managing and storing energy, developed by EPFL’s Distributed Electrical Systems Laboratory, has been inaugurated on the school’s campus. The system, which received extensive co-financing from the Canton of Vaud, is built around an industrial-capacity battery developed by Vaud-based company Leclanché. It is now connected to the Romande Energie-EPFL solar park and will be used to conduct real-world tests on the behavior of a power grid that is fed electricity from solar panels.

The experimental storage system was inaugurated today and is now connected to the Romande Energie-EPFL solar park, one of the largest in French-speaking Switzerland. Researchers will use it to study new, industrial-scale solutions for using renewable energies (especially solar energy) and feeding them into the power distribution grid, as part of the ‘EPFL Smart Grid’ project.

Useful life far above average

The system, which is the size of a shipping container, is unique for its underlying technology: it is based on high-performance lithium-ion titanate cells manufactured by Vaud-based company Leclanché. The life of these cells is around 15,000 charge-discharge cycles, while 3,000 is more common. In addition, the cells come with ceramic separators, patented by Leclanché, which are meant to maximize safety. It is a fully integrated solution comprising storage and energy-conversion modules as well as software for the battery to communicate with the EPFL engineers.

Real-world testing

The system will be used to test the research being carried out by Professor Mario Paolone, the Head of EPFL’s Distributed Electrical Systems Laboratory. It will be able to hold up to 500 kWh, which is the equivalent of the average energy consumed by fifty Swiss households over the course of one day, while managing variations in power as a function of the sunshine. “The ability to connect reliable energy storage solutions to the grid is key for incorporating renewable energy sources in our energy mix,” said Dr. Paolone. “Because of the system’s high capacity, we will be able for the first time to carry out real-world tests on the new control methods offered by the smart grids developed at EPFL.”

A project co-financed by Canton of Vaud

This project received extensive financial support from the Canton of Vaud. As part of its “100 million for renewable energies and energy efficiency” program, the Canton allocated some two million francs to Dr. Paolone’s team. These funds are from the R&D component of that program, which, in addition to EPFL, is providing support to the School of Business and Engineering in Yverdon-les-Bains and the University of Lausanne. “This project represents an important milestone in the implementation of our energy policy, one of the objectives of which is to develop renewable energy resources at the local level,” said Jacqueline de Quattro, State Councilor and Head of the Department of Territorial Planning and the Environment.

The research involving the new system is set to last 23 months and will optimize the functioning of the various components of the new system, its management and its interoperability with an integrated electricity production and distribution network (i.e., a smart grid).

See the full article here .

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EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

From MIT: “Going solid-state could make batteries safer and longer-lasting”

MIT News

August 17, 2015
David L. Chandler

llustrations show the crystal structure of a superionic conductor. The backbone of the material is a body-centred cubic-like arrangement of sulphur anions. Lithium atoms are depicted in green, sulfur atoms in yellow, PS4 tetrahedra in purple, and GeS4 tetrahedra in blue. Researchers have revealed the fundamental relationship between anion packing and ionic transport in fast lithium-conducting materials. Image: Yan Wang

New research paves the way for rechargeable batteries with almost indefinite lifetimes, researchers say.

If you pry open one of today’s ubiquitous high-tech devices — whether a cellphone, a laptop, or an electric car — you’ll find that batteries take up most of the space inside. Indeed, the recent evolution of batteries has made it possible to pack ample power in small places.

But people still always want their devices to last even longer, or go further on a charge, so researchers work night and day to boost the power a given size battery can hold. Rare, but widely publicized, incidents of overheating or combustion in lithium-ion batteries have also highlighted the importance of safety in battery technology.

Now researchers at MIT and Samsung, and in California and Maryland, have developed a new approach to one of the three basic components of batteries, the electrolyte. The new findings are based on the idea that a solid electrolyte, rather than the liquid used in today’s most common rechargeables, could greatly improve both device lifetime and safety — while providing a significant boost in the amount of power stored in a given space.

The results are reported in the journal Nature Materials in a paper by MIT postdoc Yan Wang, visiting professor of materials science and engineering Gerbrand Ceder, and five others. They describe a new approach to the development of solid-state electrolytes that could simultaneously address the greatest challenges associated with improving lithium-ion batteries, the technology now used in everything from cellphones to electric cars.

The electrolyte in such batteries — typically a liquid organic solvent whose function is to transport charged particles from one of a battery’s two electrodes to the other during charging and discharging — has been responsible for the overheating and fires that, for example, resulted in a temporary grounding of all of Boeing’s 787 Dreamliner jets, Ceder explains. Others have attempted to find a solid replacement for the liquid electrolyte, but this group is the first to show that this can be done in a formulation that fully meets the needs of battery applications.

Solid-state electrolytes could be “a real game-changer,” Ceder says, creating “almost a perfect battery, solving most of the remaining issues” in battery lifetime, safety, and cost.

Costs have already been coming down steadily, he says. But as for safety, replacing the electrolyte would be the key, Ceder adds: “All of the fires you’ve seen, with Boeing, Tesla, and others, they are all electrolyte fires. The lithium itself is not flammable in the state it’s in in these batteries. [With a solid electrolyte] there’s no safety problem — you could throw it against the wall, drive a nail through it — there’s nothing there to burn.”

The proposed solid electrolyte also holds other advantages, he says: “With a solid-state electrolyte, there’s virtually no degradation reactions left” — meaning such batteries could last through “hundreds of thousands of cycles.”

The key to making this feasible, Ceder says, was finding solid materials that could conduct ions fast enough to be useful in a battery.

“There was a view that solids cannot conduct fast enough,” he says. “That paradigm has been overthrown.”

The research team was able to analyze the factors that make for efficient ion conduction in solids, and home in on compounds that showed the right characteristics. The initial findings focused on a class of materials known as superionic lithium-ion conductors, which are compounds of lithium, germanium, phosphorus, and sulfur, but the principles derived from this research could lead to even more effective materials, the team says.

The research that led to a workable solid-state electrolyte was part of an ongoing partnership with the Korean electronics company Samsung, through the Samsung Advanced Institute of Technology in Cambridge, Massachusetts, Ceder says. That alliance also has led to important advances in the use of quantum-dot materials to create highly efficient solar cells and sodium batteries, he adds.

This solid-state electrolyte has other, unexpected side benefits: While conventional lithium-ion batteries do not perform well in extreme cold, and need to be preheated at temperatures below roughly minus 20 degrees Fahrenheit, the solid-electrolyte versions can still function at those frigid temperatures, Ceder says.

The solid-state electrolyte also allows for greater power density — the amount of power that can be stored in a given amount of space. Such batteries provide a 20 to 30 percent improvement in power density — with a corresponding increase in how long a battery of a given size could power a phone, a computer, or a car.

The team also included MIT graduate student William Richards and postdoc Jae Chul Kim; Shyue Ping Ong at the University of California at San Diego; Yifei Mo at the University of Maryland; and Lincoln Miara at Samsung. The work is part of an alliance between MIT and the Samsung Advanced Institute of Technology focusing on the development of materials for clean energy.

See the full article here.

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