Tag Archives: #lithium-ion

How To Make Lithium-ion Batteries Invincible? (Chemistry)

Berkeley Lab researchers are developing a family of cathode materials that have all of the advantages of conventional lithium batteries but without the supply constraints

In our future electrified world, the demand for battery storage is projected to be enormous, reaching to upwards of 2 to 10 terawatt-hours (TWh) of annual battery production by 2030, from less than 0.5 TWh today. However, concerns are growing as to whether key raw materials will be adequate to meet this future demand. The lithium-ion battery – the dominant technology for the foreseeable future – has a component made of cobalt and nickel, and those two metals face severe supply constraints on the global market.

Now, after several years of research led by Lawrence Berkeley National Laboratory (Berkeley Lab), scientists have made significant progress in developing battery cathodes using a new class of materials that provide batteries with the same if not higher energy density than conventional lithium-ion batteries but can be made of inexpensive and abundant metals. Known as DRX, which stands for disordered rocksalts with excess lithium, this novel family of materials was invented less than 10 years ago and allows cathodes to be made without nickel or cobalt.

“The classic lithium-ion battery has served us well, but as we consider future demands for energy storage, its reliance on certain critical minerals exposes us not only to supply-chain risks, but also environmental and social issues,” said Ravi Prasher, Berkeley Lab’s Associate Lab Director for Energy Technologies. “With DRX materials, this offers lithium batteries the potential to be the foundation for sustainable battery technologies for the future.”

The cathode is one of the two electrodes in a battery and accounts for more than one-third of the cost of a battery. Currently the cathode in lithium-ion batteries uses a class of materials known as NMC, with nickel, manganese, and cobalt as the key ingredients.

“I’ve done cathode research for over 20 years, looking for new materials, and DRX is the best new material I’ve ever seen by far,” said Berkeley Lab battery scientist Gerbrand Ceder, who is co-leading the research. “With the current NMC class, which is restricted to just nickel, cobalt, and an inactive component made of manganese, the classic lithium-ion battery is at the end of its performance curve unless you transfer to new cathode materials, and that’s what the DRX program offers. DRX materials have enormous compositional flexibility – and this is very powerful because not only can you use all kinds of abundant metals in a DRX cathode, but you can also use any type of metal to fix any problem that might come up during the early stages of designing new batteries. That’s why we’re so excited.”

Cobalt and nickel supply-chain risks

The U.S. Department of Energy (DOE) has made it a priority to find ways to reduce or eliminate the use of cobalt in batteries. “The battery industry is facing an enormous resource crunch,” said Ceder. “Even at 2 TWh, the lower range of global demand projections, that would consume almost all of today’s nickel production, and with cobalt we’re not even close. Cobalt production today is only about 150 kilotons, and 2 TWh of battery power would require 2,000 kilotons of nickel and cobalt in some combination.”

What’s more, over two-thirds of the world’s nickel production is currently used to make stainless steel. And more than half of the world’s production of cobalt comes from the Democratic Republic of Congo, with Russia, Australia, the Philippines, and Cuba rounding out the top five producers of cobalt.

In contrast, DRX cathodes can use just about any metal in place of nickel and cobalt. Scientists at Berkeley Lab have focused on using manganese and titanium, which are both more abundant and lower cost than nickel and cobalt.

“Manganese oxide and titanium oxide cost less than $1 per kilogram whereas cobalt costs about $45 per kilogram and nickel about $18,” said Ceder. “With DRX you have the potential to make very inexpensive energy storage. At that point lithium-ion becomes unbeatable and can be used everywhere – for vehicles, the grid – and we can truly make energy storage abundant and inexpensive.”

Ordered vs. disordered

Ceder and his team developed DRX materials in 2014. In batteries, the number and speed of lithium ions able to travel into the cathode translates into how much energy and power the battery has. In conventional cathodes, lithium ions travel through the cathode material along well-defined pathways and arrange themselves between the transition metal atoms (usually cobalt and nickel) in neat, orderly layers.

Berkeley Lab battery scientists Gerbrand Ceder (left) and Guoying Chen co-lead the “deep dive” into DRX materials. © Marilyn Sargent/Berkeley Lab

What Ceder’s group discovered was that a cathode with a disordered atomic structure could hold more lithium – which means more energy – while allowing for a wider range of elements to serve as the transition metal. They also learned that within that chaos, lithium ions can easily hop around.

In 2018, the Vehicle Technologies Office in DOE’s Office of Energy Efficiency and Renewable Energy provided funding for Berkeley Lab to take a “deep dive” into DRX materials. In collaboration with scientists at Oak Ridge National Laboratory, Pacific Northwest National Laboratory, and UC Santa Barbara, Berkeley Lab teams led by Ceder and Guoying Chen have made tremendous progress in optimizing DRX cathodes in lithium-ion batteries.

For example, the charge rate – or how fast the battery can charge – of these materials was initially very low, and its stability was also poor. The research team has found ways to address both of these issues through modeling and experimentation. Studies on using fluorination to improve stability have been published in Advanced Functional Materials and Advanced Energy Materials; research on how to enable a high charging rate was recently published in Nature Energy.

Illustration of a DRX cathode’s “disordered” atomic structure (right) versus the “ordered” atomic structure of a conventional cathode. A disordered cathode structure can store more lithium – which means more energy – while allowing for a wider range of elements to serve as the transition metal. © Berkeley Lab

Since DRX can be made with many different elements, the researchers have also been working on which element would be best to use, hitting the sweet spot of being abundant, inexpensive, and providing good performance. “DRX has now been synthesized with almost the whole periodic table,” Ceder said.

“This is science at its best – fundamental discoveries that will serve as the bedrock of systems in future homes, vehicles, and grids,” said Noel Bakhtian, director of Berkeley Lab’s Energy Storage Center. “What has made Berkeley Lab so successful in battery innovation for decades now is our combination of breadth and depth of expertise – from fundamental discovery to characterization, synthesis, and manufacturing, as well as energy markets and policy research. Collaboration is key – we partner with industry and beyond to solve real-world problems, which in turn helps galvanize the world-leading science we do at the Lab.”

Fast progress

New battery materials have traditionally taken 15 to 20 years to commercialize; Ceder believes progress on DRX materials can be accelerated with a larger team. “We’ve made great progress in the last three years with the deep dive,” Ceder said. “We’ve come to the conclusion that we’re ready for a bigger team, so we can involve people with a more diverse set of skills to really refine this.”

An expanded research team could move quickly to address the remaining issues, including improving the cycle life (or the number of times the battery can be recharged and discharged over its lifetime) and optimizing the electrolyte, the chemical medium that allows the flow of electrical charge between the cathode and anode. Since being developed in Ceder’s lab, groups in Europe and Japan have also launched large DRX research programs.

“Advances in battery technologies and energy storage will require continued breakthroughs in the fundamental science of materials,” said Jeff Neaton, Berkeley Lab’s Associate Lab Director for Energy Sciences. “Berkeley Lab’s expertise, unique facilities, and capabilities in advanced imaging, computation, and synthesis allow us to study materials at the scale of atoms and electrons. We are well poised to accelerate the development of promising materials like DRX for clean energy.”

Featured image: Jingyang Wang holds up a ceramic palette sample prepared for the DRX research program co-led by Gerbrand Ceder and Guoying Chen at Berkeley Lab. © Marilyn Sargent/Berkeley Lab


Reference: Huang, J., Zhong, P., Ha, Y. et al. Non-topotactic reactions enable high rate capability in Li-rich cathode materials. Nat Energy (2021). https://doi.org/10.1038/s41560-021-00817-6


Provided by LBL

Scientists Discover How Oxygen Loss Saps A Lithium-ion Battery’s Voltage (Chemistry)

Measuring the process in unprecedented detail gives them clues to how to minimize the problem and protect battery performance.BY GLENNDA CHUI

When lithium ions flow in and out of a battery electrode during charging and discharging, a tiny bit of oxygen seeps out and the battery’s voltage – a measure of how much energy it delivers – fades an equally tiny bit. The losses mount over time, and can eventually sap the battery’s energy storage capacity by 10-15%.

Now researchers have measured this super-slow process with unprecedented detail, showing  how the holes, or vacancies, left by escaping oxygen atoms change the electrode’s structure and chemistry and gradually reduce how much energy it can store.

The results contradict some of the assumptions scientists had made about this process and could suggest new ways of engineering electrodes to prevent it.

The research team from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University described their work in Nature Energy today.

“We were able to measure a very tiny degree of oxygen trickling out, ever so slowly, over hundreds of cycles,” said Peter Csernica, a Stanford PhD student who worked on the experiments with Associate Professor Will Chueh. “The fact that it’s so slow is also what made it hard to detect.”

A two-way rocking chair

Lithium-ion batteries work like a rocking chair, moving lithium ions back and forth between two electrodes that temporarily store charge. Ideally, those ions are the only things moving in and out of the billions of nanoparticles that make up each electrode. But researchers have known for some time that oxygen atoms leak out of the particles as lithium moves back and forth. The details have been hard to pin down because the signals from these leaks are too small to measure directly.

lithium_ion_oxygen_migration_sv_final.jpg

Illustration of oxygen atoms leaving the atomic lattice of a lithium-ion battery nanoparticle as lithium flows in
Scientists at SLAC and Stanford have made detailed measurements of how oxygen seeps out of the billions of nanoparticles that make up lithium-ion battery electrodes, degrading the battery’s voltage and energy efficiency over time. In this illustration, the pairs of red spheres are escaping oxygen atoms and purple spheres are metal ions. This new understanding could lead to new ways to minimize the problem and improve battery performance. (Greg Stewart/SLAC National Accelerator Laboratory)

“The total amount of oxygen leakage, over 500 cycles of battery charging and discharging, is 6%,” Csernica said. “That’s not such a small number, but if you try to measure the amount of oxygen that comes out during each cycle, it’s about one one-hundredth of a percent.”

In this study, researchers measured the leakage indirectly instead, by looking at how oxygen loss modifies the chemistry and structure of the particles. They tracked the process at several length scales – from the tiniest nanoparticles to clumps of nanoparticles to the full thickness of an electrode.

Because it’s so difficult for oxygen atoms to move around in solid materials at the temperatures where batteries operate, the conventional wisdom has been that the oxygen leaks come only from the surfaces of nanoparticles, Chueh said, although this has been up for debate.  

To get a closer look at what’s happening, the research team cycled batteries for different amounts of time, took them apart, and sliced the electrode nanoparticles for detailed examination at Lawrence Berkeley National Laboratory’s Advanced Light Source. There, a specialized X-ray microscope scanned across the samples, making high-res images and probing the chemical makeup of each tiny spot. This information was combined with a computational technique called ptychography to reveal nanoscale details, measured in billionths of a meter.

Meanwhile, at SLAC’s Stanford Synchrotron Light Source, the team shot X-rays through entire electrodes to confirm that what they were seeing at the nanoscale level was also true at a much larger scale.

A burst, then a trickle

Comparing the experimental results with computer models of how oxygen loss might occur, the team concluded that an initial burst of oxygen escapes from the surfaces of particles, followed by a very slow trickle from the interior. Where nanoparticles glommed together to form larger clumps, those near the center of the clump lost less oxygen than those near the surface.

Another important question, Chueh said, is how the loss of oxygen atoms affects the material they left behind. “That’s actually a big mystery,” he said. “Imagine the atoms in the nanoparticles are like close-packed spheres. If you keep taking oxygen atoms out, the whole thing could crash down and densify, because the structure likes to stay closely packed.”

Since this aspect of the electrode’s structure could not be directly imaged, the scientists again compared other types of experimental observations against computer models of various oxygen loss scenarios. The results indicated that the vacancies do persist – the material does not crash down and densify – and suggest how they contribute to the battery’s gradual decline.

“When oxygen leaves, surrounding manganese, nickel and cobalt atoms migrate. All the atoms are dancing out of their ideal positions,” Chueh said. “This rearrangement of metal ions, along with chemical changes caused by the missing oxygen, degrades the voltage and efficiency of the battery over time. People have known aspects of this phenomenon for a long time, but the mechanism was unclear.”

Now, he said, “we have this scientific, bottom-up understanding” of this important source of battery degradation, which could lead to new ways of mitigating oxygen loss and its damaging effects.

Chueh is an investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC. The Advanced Light Source, Stanford Synchrotron Radiation Lightsource and Spallation Neutron Source at Oak Ridge National Laboratory, where parts of this work were performed, are DOE Office of Science user facilities. Major funding came from the DOE Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, and samples were provided by the Samsung Advanced Institute of Technology Global Research Outreach program.


Reference: Peter M. Csernica et al., Nature Energy, 14 June 2021 (10.1038/s41560-021-00832-7)


Provided by SLAC

A New Type of Battery That Can Charge Ten Times Faster Than a Lithium-ion Battery Created (Chemistry)

Moreover, it is safer in terms of potential fire hazards and has a lower environmental impact

It is difficult to imagine our daily life without lithium-ion batteries. They dominate the small format battery market for portable electronic devices, and are also commonly used in electric vehicles. At the same time, lithium-ion batteries have a number of serious issues, including: a potential fire hazard and performance loss at cold temperatures; as well as a considerable environmental impact of spent battery disposal.

According to the leader of the team of researchers, Professor in the Department of Electrochemistry at St Petersburg University Oleg Levin, the chemists have been exploring redox-active nitroxyl-containing polymers as materials for electrochemical energy storage. These polymers are characterised by a high energy density and fast charging and discharging speed due to fast redox kinetics. One challenge towards the implementation of such a technology is the insufficient electrical conductivity. This impedes the charge collection even with highly conductive additives, such as carbon.

Looking for solutions to overcome this problem, the researchers from St Petersburg University synthesised a polymer based on the nickel-salen complex (NiSalen). The molecules of this metallopolymer act as a molecular wire to which energy-intensive nitroxyl pendants are attached. The molecular architecture of the material enables high capacitance performance to be achieved over a wide temperature range.

‘We came up with the concept of this material in 2016. At that time, we began to develop a fundamental project “Electrode materials for lithium-ion batteries based on organometallic polymers”. It was supported by a grant from the Russian Science Foundation. When studying the charge transport mechanism in this class of compounds, we discovered that there are two keys directions of development. Firstly, these compounds can be used as a protective layer to cover the main conductor cable of the battery, which would be otherwise made of traditional lithium-ion battery materials. And secondly, they can be used as an active component of electrochemical energy storage materials,’ explains Oleg Levin.

Professor in the Department of Electrochemistry at St Petersburg University Oleg Levin © SPbU

The polymer took over three years to develop. In the first year, the scientists tested the concept of the new material: they combined individual components to simulate the electrically conducting backbone and redox-active nitroxyl-containing pendants. It was essential to make certain that all parts of the structure worked in conjunction and reinforced each other. The next stage was the chemical synthesis of the compound. It was the most challenging part of the project. This is because some of the components are extremely sensitive and even the slightest error of a scientist may cause degradation of the samples.

Of the several polymer specimens obtained, only one was found to be sufficiently stable and efficient. The main chain of the new compound is formed by complexes of nickel with salen ligands. A stable free radical, capable of rapid oxidation and reduction (charge and discharge), has been linked to the main chain via covalent bonds.

‘A battery manufactured using our polymer will charge in seconds – about ten times faster than a traditional lithium-ion battery. This has already been demonstrated through a series of experiments. However, at this stage, it is still lagging behind in terms of capacity – 30 to 40% lower than in lithium-ion batteries. We are currently working to improve this indicator while maintaining the charge-discharge rate,’ says Oleg Levin.

The cathode for the new battery has been fabricated – a positive electrode for use in chemical current sources. Now we need the negative electrode – the anode. In fact, it does not have to be created from scratch – it can be selected from the existing ones. Paired together they will form a system that, in some areas, may soon supersede lithium-ion batteries.

‘The new battery is capable of operating at low temperatures and will be an excellent option where fast charging is crucial. It is safe to use – there is nothing that may pose a combustion hazard, unlike the cobalt-based batteries that are widespread today. It also contains significantly less metals that can cause environmental harm. Nickel is present in our polymer in a small amount, but there is much less of it than in lithium-ion batteries,’ says Oleg Levin.

Featured image: Symbolic representation of the chemical formula of the new polymer © Anatoliy A. Vereshchagin


Reference: A. A. Vereshchagin, D. A. Lukyanov, I. R. Kulikov, N. A. Panjwani, E. A. Alekseeva, J. Behrends, O. V. Levin, Batteries & Supercaps 2021, 4, 336. https://doi.org/10.1002/batt.202000220 https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/batt.202000220


Provided by St. Petersburg State University

Reactive Boride Infusion Stabilizes Ni-rich Cathodes for Lithium-ion Batteries (Chemistry)

Their findings have been published in the March 2021 issue of Nature Energy.

A new coating for lithium-ion batteries (LIBs), developed by scientists at UNIST promises extended driving for future electric vehicles (EVs). The coating, described in a paper published in the journal Nature Energy, when applied to LIBs is shown to have improved cycling stability even after being charged and discharged more than 500 times. As a result, the development of EV batteries that can drive longer distances with a single battery charge has gained considerable momentum.

Distinguished Professor Jaephil Cho and his research team in the School of Energy and Chemical Engineering at UNIST unveiled a new coating technology that can greatly suppress intergranular cracking, chemical side reactions, and impedance growth. According to the research team, this is extraordinary given that it happens at room temperature, and the secondary particle does not alter the crystalline bulk, but produces drastic changes in the grain boundaries (GBs) as they are infiltrated by reactive wetting.

Figure 1. Schematic coating-plus-infusion microstructure in which CoxB uniformly coats the surface of NCM secondary particle and infuses into GBs between the NCM primary particles. © UNIST

Nickel-rich (Ni-rich) materials are considered promising cathode materials, as they can deliver higher capacity at lower costs. However, conventional Ni-rich cathodes have been limited in terms of short lifespans, caused by microcracking and the side reactions of the electrolyte due to repeated charging/discharging operation. For this reason, in order to prevent electrolyte degradation, a protective coating is being applied onto the surfaces of all materials that are currently being produced with heat treatment at 700°C or higher. However, there had been problems with poor performance and high production costs.

In the study, the research team has presented a room-temperature synthesis route to achieve a full surface coverage of secondary particles and facile infusion into grain boundaries, and thus offer a complete ‘coating-plus-infusion’ strategy. Through this method, they constructed a high-quality cobalt boride (CoxB) metallic glass infusion of NCM secondary particles by reactive wetting. Under the strong driving force of an interfacial chemical reaction, nanoscale cobalt boride (CoxB) metallic glass not only completely wraps around the secondary particle surfaces, but also infuses into the grain boundaries (GBs) between primary particles. This is extraordinary given that it happens at room temperature, and the secondary particle does not alter the crystalline bulk, but produces drastic changes in the GBs as they are infiltrated by reactive wetting. Consequently, it offers superior electrochemical performance and better safety by mitigating the entwined cathode-side intergranular SCC, microstructural degradation, and side reactions, as well as the TM crossover effect to the anode.

Figure 2. Superior electrochemical performance of CoxB–NCM over pristine NCM. (e) Cycling performance of CoxB–NCM/Gr and pristine NCM/Gr full-cells at 1.0C in the range of 2.8−4.3 V at 25 °C. Inset: photo of an assembled pouch cell. © UNIST

Their findings reveal that the battery, constructed with the new coating method exhibited an impressive 95% capacity retention over 500 cycles, which is about 20% improved life retention rate compared to the existing Ni-rich materials. Not only that it has also dramatically improved the rate capability and cycling stability of NCM, including under high-discharge rate and high-temperature (45 °C) conditions, as it greatly suppressed intergranular cracking, side reactions and impedance growth.

The findings of this research have been published in the March 2021 issue of Nature Energy. It has been carried out in collaboration with Professor Ju Li’s research group from the MIT Department of Materials Science and Engineering.

Featured image: Distinguished Professor Jaephil Cho and his research team in the School of Energy and Chemical Engineering at UNIST. © UNIST


Journal Reference
Moonsu Yoon, Yanhao Dong, Jaeseong Hwang, et al., “Reactive boride infusion stabilizes Ni-rich cathodes for lithium-ion batteries,” Nature Energy, (2021).


Provided by UNIST

How To Prevent Short-circuiting in Next-gen Lithium Batteries? (Chemistry)

New findings may help unleash the potential of high-powered, solid-electrolyte lithium batteries.

As researchers push the boundaries of battery design, seeking to pack ever greater amounts of power and energy into a given amount of space or weight, one of the more promising technologies being studied is lithium-ion batteries that use a solid electrolyte material between the two electrodes, rather than the typical liquid.

But such batteries have been plagued by a tendency for branch-like projections of metal called dendrites to form on one of the electrodes, eventually bridging the electrolyte and shorting out the battery cell. Now, researchers at MIT and elsewhere have found a way to prevent such dendrite formation, potentially unleashing the potential of this new type of high-powered battery.

The findings are described in the journal Nature Energy, in a paper by MIT graduate student Richard Park, professors Yet-Ming Chiang and Craig Carter, and seven others at MIT, Texas A&M University, Brown University, and Carnegie Mellon University.

These diagrams illustrate the two different configurations the researchers used to minimize dendrite formation, one using a semi-solid electrode and one using a liquid layer between the solid electrode and the solid electrolyte.
Credits: Courtesy of the researchers

Solid-state batteries, Chiang explains, have been a long-sought technology for two reasons: safety and energy density. But, he says, “the only way you can reach the energy densities that are interesting is if you use a metal electrode.” And while it’s possible to couple that metal electrode with a liquid electrolyte and still get good energy density, that does not provide the same safety advantage as a solid electrolyte does, he says.

Solid state batteries only make sense with metal electrodes, he says, but attempts to develop such batteries have been hampered by the growth of dendrites, which eventually bridge the gap between the two electrode plates and short out the circuit, weakening or inactivating that cell in a battery.

It’s been known that dendrites form more rapidly when the current flow is higher — which is generally desirable in order to allow rapid charging. So far, the current densities that have been achieved in experimental solid-state batteries have been far short of what would be needed for a practical commercial rechargeable battery. But the promise is worth pursuing, Chiang says, because the amount of energy that can be stored in experimental versions of such cells, is already nearly double that of conventional lithium-ion batteries.

The team solved the dendrite problem by adopting a compromise between solid and liquid states. They made a semisolid electrode, in contact with a solid electrolyte material. The semisolid electrode provided a kind of self-healing surface at the interface, rather than the brittle surface of a solid that could lead to tiny cracks that provide the initial seeds for dendrite formation.

The idea was inspired by experimental high-temperature batteries, in which one or both electrodes consist of molten metal. According to Park, the first author of the paper, the hundreds-of-degrees temperatures of molten-metal batteries would never be practical for a portable device, but the work did demonstrate that a liquid interface can enable high current densities with no dendrite formation. “The motivation here was to develop electrodes that are based on carefully selected alloys in order to introduce a liquid phase that can serve as a self-healing component of the metal electrode,” Park says.

The arrow points to the branch-like dendrite formations on the electrode. Credits: Courtesy of the researchers

The material is more solid than liquid, he explains, but resembles the amalgam dentists use to fill a cavity — solid metal, but still able to flow and be shaped. At the ordinary temperatures that the battery operates in, “it stays in a regime where you have both a solid phase and a liquid phase,” in this case made of a mixture of sodium and potassium. The team demonstrated that it was possible to run the system at 20 times greater current than using solid lithium, without forming any dendrites, Chiang says. The next step was to replicate that performance with an actual lithium-containing electrode.

In a second version of their solid battery, the team introduced a very thin layer of liquid sodium potassium alloy in between a solid lithium electrode and a solid electrolyte. They showed that this approach could also overcome the dendrite problem, providing an alternative approach for further research.

The new approaches, Chiang says, could easily be adapted to many different versions of solid-state lithium batteries that are being investigated by researchers around the world. He says the team’s next step will be to demonstrate this system’s applicability to a variety of battery architectures. Co-author Viswanathan, professor of mechanical engineering at Carnegie Mellon University, says, “We think we can translate this approach to really any solid-state lithium-ion battery. We think it could be used immediately in cell development for a wide range of applications, from handheld devices to electric vehicles to electric aviation.”

“Metal penetration through solid electrolyte separators is a key challenge facing high energy-density batteries, and to date much attention has been directed toward the properties of the separator material through which the metal penetrates,” says Paul Albertus, an associate professor of chemical and biomolecular engineering at the University of Maryland, who was not associated with this research. Noting that the new work focuses instead on the properties of the metal electrode itself, he says the research “is important for both setting scientific priorities for understanding metal penetration, as well as developing innovations to help mitigate this important failure mode.”

The team also included Christopher Eschler, Cole Fincher, and Andres Badel at MIT; Pinwen Guan at Carnegie Mellon University; and Brian Sheldon at Brown University. The work was supported by the U.S. Department of Energy, the National Science Foundation, and the MIT-Skoltech Next Generation Program.

Featured image: This photograph shows a metal electrode (the textured inner circle) on a grey disc of solid electrolyte. After being tested through many charging-discharging cycles, the electrolyte shows the beginnings of dendrite formation on its surface. Credits: Courtesy of the researchers


Reference: Park, R.JY., Eschler, C.M., Fincher, C.D. et al. Semi-solid alkali metal electrodes enabling high critical current densities in solid electrolyte batteries. Nat Energy (2021). https://www.nature.com/articles/s41560-021-00786-w https://doi.org/10.1038/s41560-021-00786-w


Provided by MIT

Material From Russia Will Triple the Capacity of Lithium-ion Batteries (Material Science)

The scientists of the National University of Science and Technology “MISIS” (NUST MISIS) being a part of an international team of researches managed to increase the capacity and extend the service life of lithium-ion batteries. According to the researchers, they have synthesized a new nanomaterial that can replace low-efficiency graphite used in lithium-ion batteries today. The results of the research are published in the Journal of Alloys and Compounds.

Lithium-ion batteries are widely used for household appliances from smartphones to electric vehicles. The charge-discharge cycle in such battery is provided by the movement of lithium ions between two electrodes — from a negatively charged anode to a positively charged cathode.

The scope of application of lithium-ion batteries is constantly expanding, but at the same time, according to the scientists, their capacity is still limited by the properties of graphite — the main anode material. Scientists from NUST MISIS managed to obtain a new material for anodes that can provide a significant increase in capacity and extend battery service life.

“Porous nanostructured microspheres with the composition Cu0.4Zn0.6Fe2O4, that we have extracted, used as anode material provide three times higher capacity than the batteries existing on market. Besides, it allows to increase the number of charge-discharge cycles by 5 times compared to other promising alternatives to graphite. This improvement is achieved due to a synergistic effect with a combination of a special nanostructure and the composition of used elements”, 

— Evgeny Kolesnikov, an assistant at the Department of Functional Nanosystems and High-Temperature Materials, NUST MISIS said.

The synthesis of the final material happens via one step process without intermediate stages due to the use of the spray-pyrolysis method. As the scientists explained, aqueous solution with ions of special metals is converted into fog with the help of ultrasound, and then water is evaporated at temperatures up to 1200 ° C with decomposition of the original metal salts. As the result, micron or submicron spheres with the porosity, that is required to operate in a lithium-ion system, are extracted.

Electrochemical studies of the material synthesized by NUST MISIS specialists were carried out by the scientists from the Seoul National University of Science and Technology (Republic of Korea), the Norwegian University of Science and Technology (Norway), and the SRM Institute of Science and Technology (India).

The research team intends to continue researches for new even more efficient compositions of battery electrodes in the future.

Featured image: Evgeny Kolesnikov, an assistant at the Department of Functional Nanosystems and High-Temperature Materials, NUST MISIS © Sergey Gnuskov/NUST MISIS


Reference: Gopalu Karunakaran, Govindhan Maduraiveeran, Evgeny Kolesnikov, Suresh Kannan Balasingam, Denis Kuznetsov, Manab Kundu, Hollow-structured Cu0.4Zn0.6Fe2O4 as a novel negative electrode material for high-performance lithium-ion batteries, Journal of Alloys and Compounds, Volume 865, 2021, 158769, ISSN 0925-8388, https://doi.org/10.1016/j.jallcom.2021.158769. (https://www.sciencedirect.com/science/article/pii/S0925838821001766)


Provided by MISIS

Silicon Anode Structure Generates New Potential For Lithium-ion Batteries (Material Science)

Highlights

  • New research has identified a nanostructure that improves the anode in lithium-ion batteries
  • Instead of using graphite for the anode, the researchers turned to silicon: a material that stores more charge but is susceptible to fracturing
  • The team made the silicon anode by depositing silicon atoms on top of metallic nanoparticles
  • The resulting nanostructure formed arches, increasing the strength and structural integrity of the anode
  • Electrochemical tests showed the lithium-ion batteries with the improved silicon anodes had a higher charge capacity and longer lifespan

Press release

New research conducted by the Okinawa Institute of Science and Technology Graduate University (OIST) has identified a specific building block that improves the anode in lithium-ion batteries. The unique properties of the structure, which was built using nanoparticle technology, are revealed and explained today in Communications Materials.

Powerful, portable and rechargeable, lithium-ion batteries are crucial components of modern technology, found in smartphones, laptops and electric vehicles. In 2019, their potential to revolutionize how we store and consume power in the future, as we move away from fossil fuels, was notably recognized, with the Nobel Prize co-awarded to new OIST Board of Governors member, Dr. Akira Yoshino, for his work developing the lithium-ion battery.

Traditionally, graphite is used for the anode of a lithium-ion battery, but this carbon material has major limitations.

“When a battery is being charged, lithium ions are forced to move from one side of the battery – the cathode – through an electrolyte solution to the other side of the battery – the anode. Then, when a battery is being used, the lithium ions move back into the cathode and an electric current is released from the battery,” explained Dr. Marta Haro, a former researcher at OIST and first author of the study. “But in graphite anodes, six atoms of carbon are needed to store one lithium ion, so the energy density of these batteries is low.”

With science and industry currently exploring the use of lithium-ion batteries to power electric vehicles and aerospace craft, improving energy density is critical. Researchers are now searching for new materials that can increase the number of lithium ions stored in the anode.

One of the most promising candidates is silicon, which can bind four lithium ions for every one silicon atom.

“Silicon anodes can store ten times as much charge in a given volume than graphite anodes – a whole order of magnitude higher in terms of energy density,” said Dr. Haro. “The problem is, as the lithium ions move into the anode, the volume change is huge, up to around 400%, which causes the electrode to fracture and break.”

The large volume change also prevents stable formation of a protective layer that lies between the electrolyte and the anode. Every time the battery is charged, this layer therefore must continually reform, using up the limited supply of lithium ions and reducing the lifespan and rechargeability of the battery.

“Our goal was to try and create a more robust anode capable of resisting these stresses, that can absorb as much lithium as possible and ensure as many charge cycles as possible before deteriorating,” said Dr. Grammatikopoulos, senior author of the paper. “And the approach we took was to build a structure using nanoparticles.”

In a previous paper, published in 2017 in Advanced Science, the now-disbanded OIST Nanoparticles by Design Unit developed a cake-like layered structure, where each layer of silicon was sandwiched between tantalum metal nanoparticles. This improved the structural integrity of the silicon anode, preventing over-swelling.

In chamber 1, the nanoparticles, made from tantalum metal, are grown. Within this chamber, individual tantalum atoms clump together, similar to the formation of rain droplets. In chamber 2, the nanoparticles are mass filtered, removing ones that are too large or too small. In chamber 3, a layer of nanoparticles is deposited. This layer is then “sprayed” with isolated silicon atoms, forming a silicon layer. This process can then be repeated to create a multi-layered structure. Credit: Schematic created by Pavel Puchenkov, OIST Scientific Computing & Data Analysis Section.

While experimenting with different thicknesses of the silicon layer to see how it affected the material’s elastic properties, the researchers noticed something strange.

“There was a point at a specific thickness of the silicon layer where the elastic properties of the structure completely changed,” said Theo Bouloumis, a current PhD student at OIST who was conducting this experiment. “The material became gradually stiffer, but then quickly decreased in stiffness when the thickness of the silicon layer was further increased.  We had some ideas, but at the time, we didn’t know the fundamental reason behind why this change occurred.”

Now, this new paper finally provides an explanation for the sudden spike in stiffness at one critical thickness.

Through microscopy techniques and computer simulations at the atomic level, the researchers showed that as the silicon atoms are deposited onto the layer of nanoparticles, they don’t form an even and uniform film. Instead, they form columns in the shape of inverted cones, growing wider and wider as more silicon atoms are deposited. Eventually, the individual silicon columns touch each other, forming a vaulted structure.

The video shows that as silicon atoms are deposited in the presence of nanoparticles, columns grow in the shape of an inverted cone. Credit:  Video created by Dr. Junlei Zhao, University of Helsinki and SUSTech.

“The vaulted structure is strong, just like an arch is strong in civil engineering,” said Dr. Grammatikopoulos. “The same concept applies, just on a nanoscale.”

Importantly, the increased strength of the structure also coincided with enhanced battery performance. When the scientists carried out electrochemical tests, they found that the lithium-ion battery had an increased charge capacity. The protective layer was also more stable, meaning the battery could withstand more charge cycles.

These improvements are only seen at the precise moment that the columns touch. Before this moment occurs, the individual pillars are wobbly and so cannot provide structural integrity to the anode. And if silicon deposition continues after the columns touch, it creates a porous film with many voids, resulting in a weak, sponge-like behavior.

In the first stage, the silicon film exists as a rigid but wobbly columnar structure. In the second stage, the columns touch at the top, forming a vaulted structure, which is strong due to arch action. In the third stage, further deposition of silicon atoms results in a sponge-like structure. The red dashed lines show how the silicon deforms as a force is applied. Credit:  Schematic created by Dr. Panagiotis Grammatikopoulos, OIST Nanoparticles by Design Unit and Particle Technology Laboratory, ETH Zürich

This reveal of the vaulted structure and how it gains its unique properties not only acts as an important step forward towards the commercialization of silicon anodes in lithium-ion batteries, but also has many other potential applications within material sciences.

“The vaulted structure could be used when materials are needed that are strong and able to withstand various stresses, such as for bio-implants or for storing hydrogen,” said Dr. Grammatikopoulos. “The exact type of material you need – stronger or softer, more flexible or less flexible – can be precisely made, simply by changing the thickness of the layer. That’s the beauty of nanostructures.”


Article information

Journal: Communications Materials
Title: Nano-vault architecture mitigates stress in silicon-based anodes for lithium-ion batteries
Authors: Marta Haro, Pawan Kumar, Junlei Zhao, Panagiotis Koutsogiannis, Alexander James Porkovich, Zakaria Ziadi, Theodoros Bouloumis, Vidyadhar Singh, Emilio J. Juarez-Perez, Evropi Toulkeridou, Kai Nordlund, Flyura Djurabekova, Mukhles Sowwan, Panagiotis Grammatikopoulos
DOI: 10.1038/s43246-021-00119-0


Provided by OIST

Batteries That Can Be Assembled in Ambient Air (Chemistry)

The honor of the 2020 Nobel Prize in Chemistry went to those who developed lithium-ion rechargeable batteries. These batteries have become an essential energy source for electronic devices ranging from small IT devices to electric vehicles. Tesla, a leading U.S. automaker, recently emphasized the need to establish an innovative production system and reduce battery cost. The price of batteries accounts for a large portion of electric vehicles and cost reduction is vital to popularizing them.

A joint research team, led by Professor Soojin Park and Ph.D. candidate Hye Bin Son of POSTECH’s Department of Chemistry with Professor Seungmin Yoo of Ulsan College, has successfully developed a multi-functional separator which allows the batteries to function even when the pouch cell is assembled in ambient air. These findings were introduced in the latest online edition of Energy Storage Materials.

Since the electrolyte inside the battery reacts with moisture to cause deterioration, lithium-ion batteries are typically assembled in a dry room which maintains less than 1% humidity levels. However, maintaining a dry room is rather costly.

To solve this issue, studies have been conducted to suppress impurities – such as moisture or hydrofluoric acid – by injecting additives into the electrolytes. But these can cause unwanted side reactions during the battery operation. In fact, when batteries are activated at a high temperature (50? or higher), even a small bit of moisture causes faster performance deterioration. Therefore, there is a need for a material capable of trapping moisture and impurities in the battery without adverse electrochemical reactions to the additives.

To this, the joint research team introduced functional materials that can trap impurities on the surface of the separator to increase thermal stability and improve battery performance. This multi-functional separator demonstrated excellent heat resistance (shrinkage within 10% after 30 minutes of storage at 140?. Conventional separator had 50% shrinkage) and further showed improved electrochemical performance at the high temperature of 55? (79% of the initial capacity maintained after 100 charging cycles).

Additionally, the researchers confirmed the effectiveness of the functional material in the electrolyte in the impurity-filled environment. The silane compound on the surface of the synthesized functional ceramic traps moisture and maintains the ceramic structure well, but the general ceramic material was corroded by the acidified electrolyte. Moreover, through this research, the team confirmed that this multi-functional separator produced in the ambient air this time exhibits superior lifespan than the conventional separators, confirming that it provides stable performance beyond the role of a simple separator.

“This newly developed multi-functional separator shows great stability and excellent electrochemical performance at high energy density,” remarked Professor Soojin Park who has long been studying battery separators through various approaches. “With this first successful case of fabricating batteries in ambient air, it is expected to play a big role in reducing battery cost.”

This research was conducted with the support from the National Research Foundation of Korea grant funded by the Korean government (2020 M2D8A2093081, 2018R1C1B6004908).

Featured image: Battery production in ambient air using a multi-functional separator © POSTECH


Reference: Hye Bin Son, Myoungsoo Shin, Woo-Jin Song, Dong-Yeob Han, Sungho Choi, Hyungyeon Cha, Seoha Nam, Jaephil Cho, Sinho Choi, Seungmin Yoo, Soojin Park, “A Dry Room-Free High-Energy Density Lithium-ion Batteries Enabled by Impurity Scavenging Separator Membrane”, Energy Storage Materials, Volume 36, 2021, Pages 355-364, ISSN 2405-8297,
https://doi.org/10.1016/j.ensm.2021.01.018.
(http://www.sciencedirect.com/science/article/pii/S2405829721000192)


Provided by POSTECH

Bionic Idea Boosts Lithium-ion Extraction (Chemistry)

Lithium is an energy-critical element that is considered to be a geopolitically significant resource. However, the supply of lithium may not be enough to meet continuously increasing demand. As a result, scientists are looking for new ways to extract lithium ions.

Metal ion sieving using a bioinspired nanochannel membrane (Image by XIN Weiwen)

Ion selective membranes have already been used extensively for water treatment and ion sieving in electrodialysis technology. However, conventional membranes exhibit low and useless Li+ selectivity, making them insufficient for meeting industry requirements.

Chinese scientists have recently made progress in the preparation and application of a bioinspired material that is capable of achieving controlled ion transport and sieving, especially for lithium-ion extraction.

This work, published in Matter, was completed by Prof. WEN Liping’s team at the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences and Prof. ZHANG Qianfan’s team from Beihang University.

In this research, scientists utilized nanofibers, such as from natural silk and polyethyleneimine, to decorate 2D nanosheets. Inspired by the biological structure in nature, the 2D nanosheets are self-assembled layer-by-layer to form a nacre-like stacked structure. The composited membrane acts as an ion-gating heterojunction with opposite charges and asymmetrical nanochannels.

“To be more detailed, the composited membrane shows higher toughness than other reported materials and natural nacre structures. The membrane is also able to efficiently control interlayer spacing and achieve stable ordered nanostructures,” said Prof. WEN.

The typical brick-and-mortar structure formed by nanofibers and nanosheets exhibits a long-time use in solutions. Meanwhile, the confined dehydration and charge-exclusion effects conduct Li+ through composited channels rapidly.

Experimental and theoretical results indicate Li+ shows an excellent permeation rate that is far higher than Na+, K+, Mg2+ and Ca2+ due to its small radius and low charge. Compared with mobilities in bulk, Li+ remains basically consistent with the bulk value. In stark contrast, other ions become less mobile than Li+ in bulk.

The methodology of using tailor-made 2D membranes with chemical, geometrical, and electrostatic heterostructures allows further exploration of nanofluidic phenomena inside nanochannel membranes for water treatment or power generation.

This work was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, and the Strategic Priority Research Program of the Chinese Academy of Sciences.

References: Weiwen Xin, Chao Lin, Lin Fu, Qianfan Zhang, Lei Jiang, Liping Wen, “Nacre-like Mechanically Robust Heterojunction for Lithium-Ion Extraction”, Matter, 2020. https://doi.org/10.1016/j.matt.2020.12.003 https://www.cell.com/matter/fulltext/S2590-2385(20)30672-X?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS259023852030672X%3Fshowall%3Dtrue

Provided by Chinese Academy of Sciences