Tag Archives: #battery

“Wrapping” Anodes in 3D Carbon Nanosheets:The Next Big Thing in Li-Ion Battery Technology (Chemistry)

Study finds that anchoring manganese selenide nanoparticles, an anode material, in 3D carbon nanosheets prevents their expansion in lithium-ion batteries

The lithium-ion battery is the future of sustainable energy technology, but drastic volume fluctuations in their anodes related to enhanced battery capacity raises a safety concern. Recently, researchers from the Republic of Korea have found that embedding manganese selenide anodes in a 3D carbon nanosheet matrix is an innovative, simple, and low-cost means of reducing drastic volume expansion while improving the energy density of these batteries.

Lithium-ion batteries (LIBs), which are a renewable source of energy for electrical devices or electric vehicles, have attracted much attention as the next-generation energy solution. However, the anodes of LIBs in use today have multiple inadequacies, ranging from low ionic electronic conductivity and structural changes during the charge/discharge cycle to low specific capacity, which limits the battery’s performance.

In search of a better anode material, Dr. Jun Kang of Korea Maritime and Ocean University, along with his colleagues from Pusan National University, Republic of Korea, has designed an anode that, owing to its unique structural features, overcomes many of the existing barriers of anodic efficiency. Dr. Kang explains, We focused on manganese selenide (MnSe), an affordable transition metal compound known for its high electrical conductivity and applicability in developing semiconductors and supercapacitors- as a possible candidate for the advanced LIB anode.” However, MnSe undergoes a drastic volume change (by almost 160%) during the charging-discharging cycles, which not only reduces the performance of the electrode but also raises safety issues.

In an effort to prevent this volume change, the aforementioned researchers developed a simple and low-cost process: they uniformly infused the MnSe nanoparticles into a three-dimensional porous carbon nanosheet matrix (or 3DCNM). In the newly developed anode material (which they termed “MnSe ⊂ 3DCNM”), the carbon nanosheet scaffold endowed the anchored MnSe nanoparticles with numerous advantages, such as a high number of active sites and an enhanced contact area with the electrolyte and protected them from drastic volume expansion.

The researchers were able to synthesize a variety of MnSe ⊂ 3DCNM materials. Among these, they found MnSe ⊂ 3DCNM-1.92 to exhibit the best cycle stability and rate capabilities. When combined with lithium manganese (III,IV) oxide (LiMn2O4, a commonly used cathode material) in a full cell, the team observed that MnSe ⊂ 3DCNM-1.92 remarkably continued to demonstrate superior electrochemical properties, including superior lithium ion and electron transport kinetics!

The team is excited about the potential implications of their accomplishment. As Dr. Kang explains, Using a conducive filler scaffold, we have developed an anode that boosts the battery performance while simultaneously allowing reversible energy storage. This strategy can serve as a guide for other transition metal selenides with high surface areas and stable nanostructures, with applications in storage systems, electrocatalysis, and semiconductors.

Along with this new development in the field of LIBs, the possibility of realizing a greener future becomes brighter!

Featured image credit: KMOU


Reference: Litao Yu, Liguo Zhang, Jun Kang, Kwang Ho Kim, Facile synthesis of Manganese selenide anchored in Three-Dimensional carbon nanosheet matrix with enhanced Lithium storage properties, Chemical Engineering Journal, Volume 423, 2021, 130243, ISSN 1385-8947, https://doi.org/10.1016/j.cej.2021.130243. (https://www.sciencedirect.com/science/article/pii/S1385894721018313)


Provided by KMOU

Altered Microstructure Improves Organic-Based, Solid State Lithium EV Battery (Material Science)

Ethanol Solvent Boosts Battery Energy Density, A Step Toward Better EVs Of The Future

Only 2% of vehicles are electrified to date, but that is projected to reach 30% in 2030. A key toward improving the commercialization of electric vehicles (EVs) is to heighten their gravimetric energy density – measured in watt hours per kilogram – using safer, easily recyclable materials that are abundant. Lithium-metal in anodes are considered the “holy grail” for improving energy density in EV batteries compared to incumbent options like graphite at 240 Wh/kg in the race to reach more competitive energy density at 500 Wh/kg.

Yan Yao, Cullen Professor of electrical and computer engineering at the Cullen College of Engineering at the University of Houston, and UH post doctorate Jibo Zhang are taking on this challenge with Rice University colleagues. In a paper published June 17 in Joule, Zhang, Yao and team demonstrate a two-fold improvement in energy density for organic-based, solid state lithium batteries by using a solvent-assisted process to alter the electrode microstructure. Zhaoyang Chen, Fang Hao, Yanliang Liang of UH, Qing Ai, Tanguy Terlier, Hua Guo and Jun Lou of Rice University co-authored the paper.

Yan Yao, UH professor
Yan Yao is Cullen Professor of electrical and computer engineering at the Cullen College of Engineering at the University of Houston. © University of Houston

“We are developing low-cost, earth-abundant, cobalt-free organic-based cathode materials for a solid-state battery that will no longer require scarce transition metals found in mines,” said Yao. “This research is a step forward in increasing EV battery energy density using this more sustainable alternative.” Yao is also Principal Investigator with the Texas Center for Superconductivity at UH (TcSUH).

Any battery includes an anode, also known as negative electrode, and a cathode, also known as positive electrode, that are separated in a battery by a porous membrane. Lithium ions flow through an ionic conductor – an electrolyte, which allows for the charging and discharging of electrons that generates electricity for, say, a vehicle.

Jibo Zhang conducted his postdoctoral studies at the University of Houston. © University of Houston

Electrolytes are usually liquid, but that is not necessary – they can also be solid, a relatively new concept. This novelty, combined with a lithium-metal anode, can prevent short-circuiting, improve energy density and enable faster charging.

Cathodes typically determine the capacity and voltage of a battery and are subsequently the most expensive part of batteries due to usage of scarce materials like cobalt – set to reach a 65,000-ton deficit in 2030. Cobalt-based cathodes are almost exclusively used in solid-state batteries due to their excellent performance; only recently have organic compound-based lithium batteries (OBEM-Li) emerged as a more abundant, cleaner alternative that is more easily recycled.

“There is major concern surrounding the supply chain of lithium-ion batteries in the United States,” said Yao. “In this work, we show the possibility of building high energy-density lithium batteries by replacing transition metal-based cathodes with organic materials obtained from either an oil refinery or biorefinery, both of which the U.S. has the largest capacity in the world.”

The solvent-assisted microstructure increased electrode energy density to 300 Wh/kg compared to the dry-mixed microstructure at just under 180 Wh/kg by substantially improving the utilization rate of active material. © University of Houston

Cobalt-based cathodes generate 800 Wh/kg of material-level specific energy, or voltage multiplied by capacity, as do OBEM-Li batteries, which was first demonstrated by the team in their earlier publication, but previous OBEM-Li batteries were limited to low mass fraction of active materials due to non-ideal cathode microstructure. This capped total energy density.

Yao and Zhang uncovered how to improve electrode-level energy density in OBEM-Li batteries by optimizing the cathode microstructure for improved ion transport within the cathode. To do this the microstructure was altered using a familiar solvent – ethanol. The organic cathode used was pyrene-4,5,9,10-tetraone, or PTO.

“Cobalt-based cathodes are often favored because the microstructure is naturally ideal but forming the ideal microstructure in an organic-based solid-state battery is more challenging,” said Zhang.

On an electrode level, the solvent-assisted microstructure increased energy density to 300 Wh/kg compared to the dry-mixed microstructure at just under 180 Wh/kg by improving the utilization rate of active material significantly. Previously, the amount of active materials could be increased but the utilization percentage was still low, near 50%. With Zhang’s contribution, that utilization rate improved to 98% and resulted in higher energy density.

“Initially I was examining the chemical properties of PTO, which I knew would oxidize the sulfide electrolyte,” Zhang said. “This led to a discussion on how we might be able to take advantage of this reaction. Together with colleagues at Rice university, we investigated the chemical composition, spatial distribution and electrochemical reversibility of the cathode-solid electrolyte interphase, which can provide us hints as to why the battery could cycle so well without capacity decay,” Zhang said.

Over the last ten years, the cost of EV batteries declined to nearly 10% of their original cost, making them commercially viable. So, a lot can happen in a decade. This research is a pivotable step in the process toward more sustainable EVs and a springboard for the next decade of research. At this rate, perhaps just as literally as euphemistically, the future looks much greener on the other side.

This research was funded by the US Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE), as part of the Battery 500 Consortium.

Featured image: In an electric vehicle battery, lithium ions flow through an ionic conductor – an electrolyte, which allows for the charging and discharging of electrons that generates electricity for the vehicle. © University of Houston


Provided by University of Houston

Newly Developed Ion-conducting Membrane Improves Performance of Alkaline-zinc Iron Flow Battery (Chemistry)

Alkaline zinc-iron flow battery (AZIFB) is well suitable for stationary energy storage applications due to its advantages of high open-cell voltage, low cost, and environmental friendliness. However, it surfers from zinc dendrite/accumulation and relatively low operation current density.

Recently, a research group led by Prof. LI Xianfeng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Science (CAS) developed layered double hydroxide (LDH) membrane with high hydroxide conductivity and ion selectivity for alkaline-zinc iron flow battery.

The study was published in Nature Communications on June 7.

In order to enhance the operating current density of AZIFB, the researchers added LDHs nano materials into the AZIFB and designed a LDHs-based composite membrane with high performance. High selectivity and superb hydroxide ion conductivity were achieved through the combination of the well-defined interlayer gallery with a strong hydrogen bond network along 2D surfaces.

They identified that surface -OH groups of LDHs layer could assist the conduction of OH by promoting proton transfer away from one water molecule to the original OH.

Because of the high ionic conductivity, the LDHs-based membrane enabled the AZIFB to operate at 200 mA cm-2, along with an energy efficiency of 82.36%.

“This study offers a new insight to design and manufacture high-performance membranes for AZIFB,” said Prof. LI.(Text by YUAN Zhizhang)

Featured image: Selective ions transport and the hydroxide ions transport in LDHs (Image by HU Jing)


Provided by DICP

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

Stabilizing Gassy Electrolytes Could Make Ultra-low Temperature Batteries Safer (Engineering)

A new technology could dramatically improve the safety of lithium-ion batteries that operate with gas electrolytes at ultra-low temperatures. Nanoengineers at the University of California San Diego developed a separator—the part of the battery that serves as a barrier between the anode and cathode—that keeps the gas-based electrolytes in these batteries from vaporizing. This new separator could, in turn, help prevent the buildup of pressure inside the battery that leads to swelling and explosions.

“By trapping gas molecules, this separator can function as a stabilizer for volatile electrolytes,” said Zheng Chen, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering who led the study.

The new separator also boosted battery performance at ultra-low temperatures. Battery cells built with the new separator operated with a high capacity of 500 milliamp-hours per gram at -40 C, whereas those built with a commercial separator exhibited almost no capacity. The battery cells still exhibited high capacity even after sitting unused for two months—a promising sign that the new separator could also prolong shelf life, the researchers said.

The team published their findings June 7 in Nature Communications.

The advance brings researchers a step closer to building lithium-ion batteries that can power vehicles in the extreme cold, such as spacecraft, satellites and deep-sea vessels.

This work builds on a previous study published in Science by the lab of UC San Diego nanoengineering professor Ying Shirley Meng, which was the first to report the development of lithium-ion batteries that perform well at temperatures as low as -60 C. What makes these batteries especially cold hardy is that they use a special type of electrolyte called a liquefied gas electrolyte, which is a gas that is liquefied by applying pressure. It is far more resistant to freezing than a conventional liquid electrolyte.

But there’s a downside. Liquefied gas electrolytes have a high tendency to go from liquid to gas. “This is the biggest safety issue with these electrolytes,” said Chen. In order to use them, a lot of pressure must be applied to condense the gas molecules and keep the electrolyte in liquid form.

To combat this issue, Chen’s lab teamed up with Meng and UC San Diego nanoengineering professor Tod Pascal to develop a way to liquefy these gassy electrolytes easily without having to apply so much pressure. The advance was made possible by combining the expertise of computational experts like Pascal with experimentalists like Chen and Meng, who are all part of the UC San Diego Materials Research Science and Engineering Center (MRSEC).

Their approach makes use of a physical phenomenon in which gas molecules spontaneously condense when trapped inside tiny, nanometer-sized spaces. This phenomenon, known as capillary condensation, enables a gas to become liquid at a much lower pressure.

The team leveraged this phenomenon to build a battery separator that would stabilize the electrolyte in their ultra-low temperature battery—a liquefied gas electrolyte made of fluoromethane gas. The researchers built the separator out of a porous, crystalline material called a metal-organic framework (MOF). What’s special about the MOF is that it is filled with tiny pores that are able to trap fluoromethane gas molecules and condense them at relatively low pressures. For example, fluoromethane typically condenses under a pressure of 118 psi at -30 C; but with the MOF, it condenses at just 11 psi at the same temperature.

“This MOF significantly reduces the pressure needed to make the electrolyte work,” said Chen. “As a result, our battery cells deliver a significant amount of capacity at low temperature and show no degradation.”

The researchers tested the MOF-based separator in lithium-ion battery cells—built with a carbon fluoride cathode and lithium metal anode—filled with fluoromethane gas electrolyte under an internal pressure of 70 psi, which is well below the pressure needed to liquefy fluoromethane. The cells retained 57% of their room temperature capacity at -40 C. By contrast, cells with a commercial separator exhibited almost no capacity with fluoromethane gas electrolyte at the same temperature and pressure.

The tiny pores of the MOF-based separator are key because they keep more electrolyte flowing in the battery, even under reduced pressure. The commercial separator, on the other hand, has large pores and cannot retain the gas electrolyte molecules under reduced pressure.

But tiny pores are not the only reason the separator works so well in these conditions. The researchers engineered the separator so that the pores form continuous paths from one end to the other. This ensures that lithium ions can still flow freely through the separator. In tests, battery cells with the new separator had 10 times higher ionic conductivity at -40 C than cells with the commercial separator.

Chen’s team is now testing the MOF-based separator on other electrolytes. “We are seeing similar effects. We can use this MOF as a stabilizer to adsorb various kinds of electrolyte molecules and improve the safety even in traditional lithium batteries, which also have volatile electrolytes.”

Paper: “Sub-Nanometer Confinement Enables Facile Condensation of Gas Electrolyte for Low-Temperature Batteries.” Co-authors include Guorui Cai*, Yijie Yin*, Dawei Xia*, Amanda A. Chen, John Holoubek, Jonathan Scharf, Yangyuchen Yang, Ki Kwan Koh, Mingqian Li, Daniel M. Davies and Matthew Mayer, UC San Diego; and Tae Hee Han, Hanyang University, Seoul, Korea.

*These authors contributed equally to this work

This work was supported by NASA’s Space Technology Research Grants Program (ECF 80NSSC18K1512), the National Science Foundation through the UC San Diego Materials Research Science and Engineering Center (MRSEC, grant DMR-2011924) and startup funds from the Jacobs School of Engineering at UC San Diego. This work was performed in part at the San Diego Nanotechnology Infrastructure (SDNI) at UC San Diego, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (grant ECCS-1542148). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This work also used the Extreme Science and Engineering Discovery Environment (XSEDE), and the Comet and Expanse supercomputers at the San Diego Supercomputing Center, which is supported by National Science Foundation (grant ACI-1548562).

Featured image: Artistic rendering of a battery separator that condenses gas electrolytes into liquid at a much lower pressure. The new separator improves battery performance in the extreme cold by keeping more electrolyte, as well as lithium ions, flowing in the battery. Credit: Chen group


Provided by UCSD

The Biodegradable Battery (Chemistry)

The number of data-transmitting microdevices, for instance in packaging and transport logistics, will increase sharply in the coming years. All these devices need energy, but the amount of batteries would have a major impact on the environment. Empa researchers have developed a biodegradable mini-capacitor that can solve the problem. It consists of carbon, cellulose, glycerin and table salt. And it works reliably.

The fabrication device for the battery revolution looks quite unconspicuous: It is a modified, commercially available 3D printer, located in a room in the Empa laboratory building. But the real innovation lies within the recipe for the gelatinous inks this printer can dispense onto a surface. The mixture in question consists of cellulose nanofibers and cellulose nanocrystallites, plus carbon in the form of carbon black, graphite and activated carbon. To liquefy all this, the researchers use glycerin, water and two different types of alcohol. Plus a pinch of table salt for ionic conductivity.

A sandwich of four layers

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The biodegradable battery consists of four layers, all flowing out of a 3D printer one after the other. The whole thing is then folded up like a sandwich, with the electrolyte in the center. Image: Gian Vaitl / Empa

To build a functioning supercapacitor from these ingredients, four layers are needed, all flowing out of the 3D printer one after the other: a flexible substrate, a conductive layer, the electrode and finally the electrolyte. The whole thing is then folded up like a sandwich, with the electrolyte in the center.

What emerges is an ecological miracle. The mini-capacitor from the lab can store electricity for hours and can already power a small digital clock. It can withstand thousands of charge and discharge cycles and years of storage, even in freezing temperatures, and is resistant to pressure and shock.

Biodegradable power supply

Best of all, though, when you no longer need it, you could toss it in the compost or simply leave it in nature. After two months, the capacitor will have disintegrated, leaving only a few visible carbon particles. The researchers have already tried this, too.

“It sounds quite simple, but it wasn’t at all,” says Xavier Aeby of Empa’s Cellulose & Wood Materials lab. It took an extended series of tests until all the parameters were right, until all the components flowed reliably from the printer and the capacitor worked. Says Aeby: “As researchers, we don’t want to just fiddle about, we also want to understand what’s happening inside our materials.”

Together with his supervisor, Gustav Nyström, Aeby developed and implemented the concept of a biodegradable electricity storage device. Aeby studied microsystems engineering at EPFL and came to Empa for his doctorate. Nyström and his team have been investigating functional gels based on nanocellulose for some time. The material is not only an environmentally friendly, renewable raw material, but its internal chemistry makes it extremely versatile.

“The project of a biodegradable electricity storage system has been close to my heart for a long time,” Nyström says. “We applied for Empa internal funding with our project, Printed Paper Batteries, and were able to start our activities with this funding. Now we have achieved our first goal.”

Application in the Internet of Things

The supercapacitor could soon become a key component for the Internet of Things, Nyström and Aeby expect. “In the future, such capacitors could be briefly charged using an electromagnetic field, for example, then they could provide power for a sensor or a microtransmitter for hours.” This could be used, for instance, to check the contents of individual packages during shipping. Powering sensors in environmental monitoring or agriculture is also conceivable – there’s no need to collect these batteries again, as they could be left in nature to degrade.

After two months buried in the soil, the capacitor has disintegrated, leaving only a few visible carbon particles. Image: Gian Vaitl/ Empa.

The number of electronic microdevices will also be increasing due to a much more widespread use of near-patient laboratory diagnostics (“point of care testing”), which is currently booming. Small test devices for use at the bedside or self-testing devices for diabetics are among them. “A disposable cellulose capacitor could also be well suited for these applications”, says Gustav Nyström.

Featured image: Xavier Aeby and Gustav Nyström invented a fully printed biodegradable battery made from cellulose and other non-toxic components. Image: Gian Vaitl / Empa


Literature

X Aeby, A Poulin, G Siqueira, MK Hausmann, G Nyström; Fully 3D Printed and Disposable Paper Supercapacitors; Advanced Materials (2021); doi.org/10.1002/adma.202101328


Provided by EMPA

Hybrid Redox-flow Battery With A Long Cycle Life (Chemistry)

Researchers use the abundant chemical element manganese as active material

Redox‑flow batteries store electrical energy in chemical compounds that are dissolved in an electrolyte. They are a particularly promising alternative to lithium‑ion batteries as stationary energy storage. A team headed by Prof. Dr. Ingo Krossing from the Institute of Inorganic and Analytical Chemistry at the University of Freiburg has succeeded in developing a non-aqueous All‑Manganese Flow battery (All-MFB) that uses sustainable manganese as its active material and has a long cycle life. The researchers present the results of their work in the latest edition of Advanced Energy Materials.

Active materials are chemical substances that are required to store energy in batteries. The Freiburg scientists have now replaced the previous active material, the element vanadium, with the much more abundant element manganese. Krossing and his team have adopted a new approach to applying the sustainable manganese in the battery: until now coupling the deposition of manganese in its elemental form with the oxidation of manganese in the oxidation state +II to manganese +III had not been used to store electrochemical energy. The newly-developed battery achieves an energy density roughly twice as high compared to the standard redox‑flow battery with vanadium.

“With the electrolytes presented in our publication, energy densities of up to 74 Wh L–1 are possible,” explains Krossing. “This was already far better in the first try than the energy density of the vanadium redox‑flow battery which has been researched since 1978.” Further optimization of the battery is necessary, according to the Freiburg chemist, “but this system describes a new and highly promising design for sustainable stationary energy storage.”

Featured image: Schematic representation of the electrochemical processes taking place in the all-Mn battery, also showing the problems, namely leaching and Mn deposition. © Schmucker et al.


Original publication:
Schmucker, M. et al., Krossing, I. (2021): Investigations Towards a Non‑Aqueous Hybrid Redox‑Flow Battery with a Manganese Based Anolyte and Catholyte. In: Advanced Energy Materials. DOI: 10.1002/aenm.202101261


Provided by Freiburg University

Biopolymer-based Electrolyte For the Dream of Zero-pollution Battery (Chemistry)

In a paper published in NANO, researchers from Guizhou Meiling Power Sources Co., Ltd., China have reviewed the recent progress in biopolymer-based electrolyte. The biopolymer materials with unique characteristics including water solubility, film-forming capability and adhesive property played a key role in the design of zero pollution lithium battery. The biopolymers mentioned in this review were polysaccharide, protein, natural rubber and other polymers.

For polysaccharide, cellulose with good wettability, low cost and good mechanical properties can enhance the mechanical strength of membranes and improve interfacial stability between electrolyte and electrode. However, the porosity control of cellulose-based membranes was still a challenge. Therefore, cellulose derivatives has been studied as electrolyte materials including alkyl cellulose, hydroxyalkyl cellulose, carboxyalkyl cellulose, cellulose esters and bacterial cellulose. In addition, chitin acted as filler of polymeric matrix to increase ionic conductivity. Anionic structure of pectin resulted in the interaction between lithium ions and polymer matrix, which favored the dissolution of lithium salts in electrolyte. Starch can improve the thermal stability of electrolyte. Chitosan contained -NH2 and -OH groups, which favored the formation of complexes with other components and promoted ionic migration. Tamarind seed polysaccharide was a highly branched polymer, which possessed film-forming nature and film transparency.

For protein, soy protein isolate (SPI) and gelatin were emphasized due to their strong interactions with electrodes. Various different functional groups of SPI facilitated the fast transport of lithium ions and effective immobilization of sulfur species. Gelatin possessed electrochemical stability and it can react with the degradation products of the liquid electrolyte to stabilize the interfaces. Epoxidized natural rubber possessed the glass transition temperature of -20 oC, high flexibility and good elasticity for contacting well with electrodes. Some other biopolymers such as agar, iota-carrageenan and eggshell membranes have also been mentioned for the electrolyte fabrication.

In summary, the starting point of choosing biopolymer as battery material is still limited to the physico-chemical consideration such as their functional groups, chain structures and intermolecular interactions. The real biological effects and ideas are still rejected or ignored during the design of lithium battery.

This work is supported by S&T Planning Project of Guizhou Province (nos. [2017]1411). Corresponding author for this study is Jiayuan Shi (jiayshi@163.com). Additional co-authors of the NANO paper is Bin Shi (ml3401@126.com).

For more insight into the research described, readers are invited to access the paper on NANO.

The paper can be found in NANO journal.

Featured image: Biopolymer-based materials have been reviewed in this work including polysaccharide, protein, natural rubber and other biopolymers to fabricate electrolytes with environmental friendliness, excellent mechanical strength, improved ionic conductivity and high lithium ion transference number for the design of zero-pollution lithium batteries. © World Scientific


Provided by World Scientific

Denmark’s Largest Battery – One Step Closer to Storing Green Power in Stones (Engineering)

The concept of storing renewable energy in stones has come one step closer to realisation with the construction of the GridScale demonstration plant. The plant will be the largest electricity storage facility in Denmark, with a capacity of 10 MWh. The project is being funded by the Energy Technology Development and Demonstration Program (EUDP) under the Danish Energy Agency.

Pea sized stones heated to 600°C in large, insulated steel tanks are at the heart of a new innovation project aiming to make a breakthrough in the storage of intermittent wind and solar electricity.

The technology, which stores electrical energy as heat in stones, is called GridScale, and could become a cheap and efficient alternative to storing power from solar and wind in lithium-based batteries. While lithium batteries are only cost-effective for the supply of energy for short periods of up to four hours, a GridScale electricity storage system will cost effectively support electricity supply for longer periods – up to about a week.

“The only real challenge with establishing 100 per cent renewable electricity supply is that we can’t save the electricity generated during windy and sunny weather for use at a later time. Demand and production do not follow the same pattern. There are not yet commercial solutions to this problem, but we hope to be able to deliver this with our GridScale energy storage system,” says Henrik Stiesdal, founder of the climate technology company Stiesdal Storage Technologies, which is behind the technology.

In brief, the GridScale technology is about heating and cooling basalt crushed to tiny, pea-sized stones in one or more sets of insulated steel tanks. The storage facility is charged through a system of compressors and turbines, which pumps heat energy from one or more storage tanks filled with cool stones to a similar number of storage tanks filled with hot stones, when there is surplus power from wind or the sun.

This means the stones in the cold tanks become very cold, while they become very hot in the hot tanks; in fact up to 600oC. The heat can be stored in the stones for many days, and the number of sets of stone-filled tanks can be varied, depending on the length of storage time required.

When there is demand for electricity again, the process reverses, so the stones in the hot tanks become colder while they become warmer in the cold tanks. The system is based on an inexpensive storage material and mature, well-known technology for charging and discharging.

“Basalt is a cheap and sustainable material that can store large amounts of energy in small spaces, and that can withstand countless charges and discharges of the storage facility. We are now developing a prototype for the storage technology to demonstrate the way forward in solving the problem of storing renewable energy – one of the biggest challenges to the development of sustainable energy worldwide,” says Ole Alm, head of development at the energy group Andel, which is also part of the project.

The GridScale prototype will be the largest storage facility in the Danish electricity system, and a major challenge will be to make the storage flexibility available on the electricity markets in a way that provides the best possible value. Consequently, this will also be part of the project.

The precise location of the prototype storage facility has yet to be decided. However, it will definitely be in the eastern part of Denmark in south or west Zealand or on Lolland-Falster, where production from new large PV units in particular is growing faster than consumption can keep up.

The full name of the innovation project is ‘GridScale – cost-effective large-scale electricity storage’, and it will run for three years with a total budget of DKK 35 million (EUR 4.7 million).  The project is being funded with DKK 21 million (EUR 2.8 million) from the Energy Technology Development and Demonstration Program (EUDP). 

In addition to the companies Stiesdal and Andel, the partner group comprises Aarhus University (AU), the Technical University of Denmark (DTU), Welcon, BWSC (Burmeister Wain Scandinavian Contractor), Energi Danmark and Energy Cluster Denmark.

The partners will provide an energy system analysis and design optimisation for a stone storage facility as well as optimize the technical concepts and mature the GridScale technology to a ready-to-market scalable solution.

For example, the European energy system model developed by AU will be combined with the model for optimising turbines developed by DTU to gain insight into the potential role of the stone storage facility in a European context and to optimise the design:

“The transition to renewable energy changes the way the energy system works – simply because wind and solar energy are not necessarily produced when we need it. Therefore, we need to find out how the technical design can best be adapted to the energy system and in which countries and when in the green transition the technology has the greatest value. We will look to identify the combination of energy technologies that will provide the greatest value for the storage solution. I think that stone storage technology has a huge potential in many places around the world and could be of great advantage in the green transition,” says Associate Professor Gorm Bruun Andresen from the Department of Mechanical and Production Engineering at Aarhus University.

Featured image: When there is a surplus of electricity from wind or solar, the energy storage is charged. This is done by a system of compressors and turbines pumping heat energy from one or more storage tanks filled with cool stones to a corresponding number of storage tanks filled with hot stones. This makes the stones in the cold tanks very cold, while it gets very hot in the hot tanks, up to 600 degrees. Illustration: Claus Rye, Stiesdal Storage Technologies.


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