New discovery will have huge impact on the development of future battery cathodes

A new paper published today in Nature Energy reveals how a collaborative team of researchers have been able to fully identify the nature of oxidised oxygen in the important battery material – Li-rich NMC – using RIXS (Resonant Inelastic X-ray Scattering) at Diamond. This compound is being closely considered for implementation in next generation Li-ion batteries because it can deliver a higher energy density than the current state-of-the-art materials, which could translate to longer driving ranges for electric vehicles. They expect that their work will enable scientists to tackle issues like battery longevity and voltage fade with Li-rich materials.

The paper, ‘First cycle voltage hysteresis in Li-rich 3d cathodes associated with molecular O2 trapped in the bulk’ by a joint team from the University of Oxford, the Henry Royce and Faraday Institutions and Diamond, examines the results of their investigations to better understand the important compound known in the battery industry as Li-rich NMC (or Li1.2Ni0.13Co0.13Mn0.54O2).   

Principal Beamline Scientist on I21 RIXS at Diamond, Kejin Zhou,said:

Our work is much about understanding the mysterious first cycle voltage hysteresis in which the O-redox process cannot be fully recovered resulting in the loss of the voltage hence the energy density.

Read more on the Diamond website

Image: A previous study (Nature 577, 502–508 (2020)) into this process made by the same research team, at the I21 beamline at Diamond, reported that, in Na-ion battery cathodes, the voltage hysteresis is related to the formation of molecular O2 trapped inside of the particles due to the migration of transition metal ions during the charging process.

High-pressure study advances understanding of promising battery materials

X-ray investigation shows systematic distortion of the crystal lattice of high-entropy oxides

In a high-pressure X-ray study, scientists have gained new insights into the characteristics of a promising new class of materials for batteries and other applications. The team led by Qiaoshi Zeng from the Center for High Pressure Science in China used the brilliant X-rays from DESY’s research light source PETRA III to analyse a so-called high-entropy oxide (HEO) under increasing pressure. The study, published in the journal Materials Today Advances is a first, but very important step paving a way for a broader picture and solid understanding of HEO materials.

Modern society requires industry to manufacture efficiently sustainable products for everyday life, for example batteries for smart phones. About five years ago, a new class of materials emerged that appears to be very promising for the design of new applications, especially batteries. These high-entropy oxides consist of at least five metals that are distributed randomly in a common simple crystal lattice, while their crystal structure can be different from each metal’s generic lattice. A popular example of a HEO material consists of 20 per cent each of cobalt, copper, magnesium, nickel and zinc for every oxygen atom, or (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O.

Read more on the DESY website

Image: Example of a high-entropy oxide between the anvils of a diamond anvil cell used to exert increasing pressure on the sample. Credit: Center of High Pressure Science, Qiaoshi Zeng

Scientists probe the chemistry of a single battery electrode particle both inside and out

The results show how a particle’s surface and interior influence each other, an important thing to know when developing more robust batteries.

The particles that make up lithium-ion battery electrodes are microscopic but mighty: They determine how much charge the battery can store, how fast it charges and discharges and how it holds up over time – all crucial for high performance in an electric vehicle or electronic device.

Cracks and chemical reactions on a particle’s surface can degrade performance, and the whole particle’s ability to absorb and release lithium ions also changes over time. Scientists have studied both, but until now they had never looked at both the surface and the interior of an individual particle to see how what happens in one affects the other.

Read more on the SSRL (SLAC National Accelerator Laboratory) website

Image: Images made with an X-ray microscope show particles within a nickel-rich layered oxide battery electrode (left). In a SLAC study, scientists welded a single charged particle to the tip of a tungsten needle (right) so they could probe its surface and interior with two X-ray instruments. The particle is about the size of a red blood cell. (S. Li et al., Nature Communications, 2020)

Longer-lasting cell phone batteries

Studies demonstrate the promise of phosphorene in electronics

Phosphorene is attracting a lot of attention lately in the energy and electronics industries, and for good reason. The theoretical capacity of the two-dimensional material—which consists of a single layer of black phosphorus—is almost seven times that of anode materials currently used in lithium-ion batteries. That could translate into real-world benefits such as significantly greater range for electric vehicles and longer battery life for cell phones.

There are a couple of strikes against phosphorene though. Commercially available black phosphorus is costly, at roughly $1000 per gram, and it breaks down quickly when it’s exposed to air. Researchers from Western University teamed up with scientists from the Canadian Light Source (CLS) at the University of Saskatchewan on a pair of studies to determine if they could address both issues.

Read more on the Canadian Light Source website

Image: Dr. Andy Sun at the Canadian Light Source.

Hope for better batteries – researchers follow the charging and discharging of silicon electrodes live

Using silicon as a material for electrodes in lithium-ion batteries promises a significant increase in battery amp-hour capacity.The shortcoming of this material is that it is easily damaged by the stress caused by charging and discharging.Scientists at the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) have now succeeded for the first time in observing this process directly on crystalline silicon electrodes in detail.Operando experiments using the BESSY II synchrotronprovided new insights into how fractures occur in silicon – and also how the material can nevertheless be utilised advantageously.

Whether in smartphones or electric cars – wherever mobile electric power needs to be available, it usually comes from rechargeable lithium-ion batteries. One of the two electrodes inside these batteries consists of graphite in which lithium ions are lodged, thereby storing electrical energy. The disadvantage of this carbon material is that its energy storage capacity is quite small – which makes frequent recharging of the battery necessary. For this reason, researchers worldwide are searching for alternative electrode materials to lengthen the battery charge/discharge cycles.

Read more on the Helmholtz Zentrum Berlin website

Image: The design of the experimental set-up shows how the structure of the silicon electrode periodically changes during charging and discharging on the basis of voltage measurements. © HZB

Seeing “under the hood” in batteries

From next-gen smartphones to longer-range electric cars and an improved power grid, better batteries are driving tech innovation. And to push batteries beyond their present-day performance, researchers want to see “under the hood” to learn how the individual ingredients of battery materials behave beneath the surface.

This could ultimately lead to battery improvements such as increased capacity and voltage.

But many of the techniques scientists use can only scratch the surface of what’s at work inside batteries, and a high-sensitivity X-ray technique at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) is attracting a growing group of scientists because it provides a deeper, more precise dive into battery chemistry.

>Read more on the Advaced Light Source at LBNL website

Image: The high-efficiency RIXS system at the Advanced Light Source’s Beamline 8.0.1
Credit: Marilyn Sargent/Berkeley Lab

How a new electrocatalyst enables ultrafast reactions

The work provides rational guidance for the development of better electrocatalysts for applications such as hydrogen-fuel production and long-range batteries for electric vehicles.

The oxygen evolution reaction (OER) is the electrochemical mechanism at the heart of many processes relevant to energy storage and conversion, including the splitting of water to generate hydrogen fuel and the operation of proposed long-range batteries for electric vehicles. Because the OER rate is a limiting factor in such processes, highly active OER electrocatalysts with long-term stability are being sought to increase reaction rates, reduce energy losses, and improve cycling stability. Catalysts incorporating rare and expensive materials such as iridium and ruthenium exhibit good performance, but an easily prepared, efficient, and durable OER catalyst based on earth-abundant elements is still needed for large-scale applications.

Key insight: shorter O-O bonds
In an earlier study, a group led by John Goodenough (2019 Nobel laureate in chemistry) measured the OER activities of two compounds with similar structures: CaCoO3 and SrCoO3. They found that the CaCoO3 exhibited higher OER activity, which they attributed to its shorter oxygen–oxygen (O-O) bonds. Inspired by this, members of the Goodenough group have now analyzed a metallic layered oxide, Na0.67CoO2, which has an even more compact structure than CaCoO3. X-ray diffraction (XRD) experiments performed at the Advanced Photon Source (APS) confirmed that the shortest O-O separation in Na0.67CoO2 is 2.30 Å, compared to 2.64 Å for CaCoO3. The researchers then compared the OER performance of Na0.67CoO2 with IrO2, Co3O4, and Co(OH)2. They found that Na0.67CoO2 exhibited the highest current density, the lowest overpotential (a measure of thermodynamic energy loss), and the most favorable Tafel slope (sensitivity of the electric current to applied potential). The Na0.67CoO2 also showed excellent stability under typical operating conditions.

>Read more on the Advanced Light Source website

Image: (extract, full image here) A new electrocatalyst prepared for this study, Na0.67CoO2, consists of two-dimensional CoO2 layers separated by Na layers (not shown). The Co ions (blue spheres) have four different positions (Co1-Co4), and the distorted Co–O octahedra have varying oxygen–oxygen (O-O) separations (thick red lines connecting red spheres). All of the O-O bonds are shorter than 2.64 Å (the length of the corresponding bonds in a comparable material), and the shortest bonds are less than 2.40 Å. It turns out that O-O separation has a strong effect on the oxygen evolution reaction (OER) in this material.

Expertise in characterising materials for lithium ion batteries

Pioneering work on materials for energy production, such as lithium ion batteries, has made ANSTO a centre of specialist capabilities and expertise.

(…)
In addition to the research on lithium-ion batteries; the team also investigates other types of batteries that can reversibly host ions, such as sodium and potassium ion batteries. 
Dr Christophe Didier, a post-doc working with Peterson at the ACNS and shared with Peterson’s University of Wollongong collaborators, published work in Advanced Energy Materials providing structural insights into layered manganese oxide electrodes for potassium-Ion batteries.
“In this case, we were able to use X-rays on an operating battery at the Australian Synchrotron,  because potassium has a lot more electrons than lithium.”
These results again confirm the importance of understanding the detailed structural evolution that underpins performance that will inform the strategic design of electrode materials for high-performance potassium ion batteries. “We do have many collaborators but we are always interested in new projects.  Because we are knowledgeable in the materials themselves, we can contribute to the selection of suitable materials as well as leading the characterisation effort.

>Read more on the Australian Synchrotron (ANSTO) website

Image: Powder diffraction instrument scientist, Dr Qinfen Gu at the Australian Synchrotron.

Cathode ‘defects’ improve battery performance

A counterintuitive finding revealed by high-precision powder diffraction analyses suggests a new strategy for building better batteries

UPTON, NY—Engineers strive to design smartphones with longer-lasting batteries, electric vehicles that can drive for hundreds of miles on a single charge, and a reliable power grid that can store renewable energy for future use. Each of these technologies is within reach—that is, if scientists can build better cathode materials.

To date, the typical strategy for enhancing cathode materials has been to alter their chemical composition. But now, chemists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have made a new finding about battery performance that points to a different strategy for optimizing cathode materials. Their research, published in Chemistry of Materials and featured in ACS Editors’ Choice, focuses on controlling the amount of structural defects in the cathode material.

“Instead of changing the chemical composition of the cathode, we can alter the arrangement of its atoms,” said corresponding author Peter Khalifah, a chemist at Brookhaven Lab and Stony Brook University.

>Read more on the NSLS-II at Brookhaven Lab website

Image: Corresponding author Peter Khalifah (left) with his students/co-authors Gerard Mattei (center) and Zhuo Li (right) at one of Brookhaven’s chemistry labs.

Sizing up red phosphorus for use in future battery technologies

A step forward in the search for better anodes for sodium-ion batteries

In 2015, the world used around 16 TW of energy, and this is predicted to rise to about 24 TW by 2035. The need for high-performing energy storage is growing, with the increased use of both intermittent, renewable power sources and electric vehicles. The current technology of choice is lithium-ion batteries (LIBs), which have high specific energies, rate capabilities, and cycle lives. However, LIBs rely on lithium and cobalt, two elements with an uneven geographical distribution. Disruptions to supply can cause price spikes, and there are concerns that the world’s total cobalt reserves may not meet future demand. Scientists are therefore investigating the potential of other battery technologies, which use cheap and widely available materials, such as sodium-ion batteries (SIBs). Although operation and manufacturing processes for SIBs are similar to those for LIBs, they cannot use the graphite anodes that are common in LIS. In research recently published in Energy Fuels, a team of researchers from the University of Oxford investigated how the particle-size distribution of red phosphorus affects the performance of composite anodes for SIBs.

Image: a) TEM image of the composite material made by mixing phosphorus (Dv90 = 0.79 μm) with graphite for 48 h in which graphene planes can be seen on the surface of the phosphorus particle. (b) Plotting the ratio between the integrated areas of the peaks fitted on the photoelectron spectra collected from the composite versus the probing depth shows that surficial P–C chemical bonds gradually decrease and P–P bonds increase as we move deeper toward the particle bulk. The areas are calculated from the fit shown in panels c–e, with the photoelectron spectra of the P 2p region acquired using increasing incident radiation energy.

>Read more on the Diamond Light Source website

Canadian researchers extend the life of rechargeable batteries

Carbon coating that extends lithium ion battery capacity by 50% could pave the way for next-generation batteries in electric vehicles.

Researchers from Western University, using the Canadian Light Source (CLS) at the University of Saskatchewan, found that adding a carbon-based layer to lithium-ion rechargeable batteries extends their life up to 50%.
The finding, recently published in the journal ACS Applied Materials and Interfaces, tackles a problem many Canadians will be familiar with: rechargeable batteries gradually hold less charge over time.
“We added a thin layer of carbon coating to the aluminum foil that conducts electric current in rechargeable batteries,” said lead researcher Dr. Xia Li of Western University. “It was a small change, but we found the carbon coating protected the aluminum foil from corrosion of electrolyte in both high voltage and high energy environments – boosting the battery capacities up to 50% more than batteries without the carbon coating.”

>Read more on the Canadian Light Source website

Image: Dr. Li in the lab. 

Using reed waste for sustainable batteries

With the changing climate, researchers are focusing on finding sustainable alternatives to conventional fuel cells and battery designs. Traditional catalysts used in vehicles contribute to increasing carbon dioxide emissions and mining for materials used in their design has a negative impact on the environment. Prof. Shuhui Sun, a researcher from the Institut National de la Recherche Scientifique (INRS) in Montreal, and his team used the Canadian Light Source (CLS) at the University of Saskatchewan to investigate an Iron-Nitrogen-Carbon catalyst using reed waste.

They hope to use the bio-based materials to create high-performance fuel cells and metal-air batteries, which could be used in electric cars. “An efficient oxygen electrocatalyst is extremely important for the development of high-performance electrochemical energy conversion and storage devices. Currently, the rare and expensive Pt-based catalysts are commonly used in these devices. Therefore, developing highly efficient and low-cost non-precious metal (e.g., Fe-based) catalysts to facilitate a sluggish cathodic oxygen reduction reaction (ORR) is a key issue for metal air batteries and fuel cells,” said Qilang Wei, the first author of the paper.

>Read more on the Canadian Light Source website

Catalyst improves cycling life of magnesium/sulfur batteries

Comprising earth-abundant elements, cathodes made of magnesium/sulfur compounds could represent the next step in battery technology. However, despite being dendrite free and having a high theoretical energy density compared with lithium batteries, magnesium/sulfur batteries have suffered from high polarization and extremely limited recharging capabilities. To gain electrochemical insights into magnesium/sulfur batteries during charge–discharge cycles, researchers used the Advanced Light Source (ALS) to investigate and optimize battery chemistry.

The in situ x-ray absorption spectroscopy (XAS) capabilities at ALS Beamlines 5.3.1 and 10.3.2 provided information on the oxidation state of sulfur under real operating conditions. The group found that the conversion of sulfur in the first discharging process was divided into three stages: formation of MgSand MgSat a fast reaction rate, reduction of MgSto Mg3S8, and a sluggish further reduction of Mg3Sto MgS. The in situ XAS analysis revealed that Mg3Sand MgS are more electrochemically inert and cannot revert to the active forms of sulfur, thereby dramatically reducing the battery’s cycling life.

>Read more on the ALS website

Image: Efforts to develop magnesium/sulfur batteries have been stymied by a loss of capacity after the first discharging process. In situ XAS revealed the accumulation of Mg3S8 and MgS during the discharging process, which are inert forms of the magnesium/sulfur compounds. Introducing a titanium-sulfide catalyst activated the compounds, reversing the chemical mechanism so that the battery could be recharged multiple times.

 

Scientists design organic cathode for high performance batteries

The new, sulfur-based material is more energy-dense, cost-effective, and environmentally friendly than traditional cathodes in lithium batteries.

Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have designed a new, organic cathode material for lithium batteries. With sulfur at its core, the material is more energy-dense, cost-effective, and environmentally friendly than traditional cathode materials in lithium batteries. The research was published in Advanced Energy Materials on April 10, 2019.

Optimizing cathode materials

From smartphones to electric vehicles, the technologies that have become central to everyday life run on lithium batteries. And as the demand for these products continues to rise, scientists are investigating how to optimize cathode materials to improve the overall performance of lithium battery systems.
“Commercialized lithium-ion batteries are used in small electronic devices; however, to accommodate long driving ranges for electric vehicles, their energy density needs to be higher,” said Zulipiya Shadike, a research associate in Brookhaven’s Chemistry Division and the lead author of the research. “We are trying to develop new battery systems with a high energy density and stable performance.”

>Read more on the NSLS-II website

Image: Lead author Zulipiya Shadike (right) is pictured at NSLS-II’s XPD beamline with lead beamline scientist and co-author Sanjit Ghose (left).

The most complete study of battery failure sees the light

An international team of researchers just published in Advanced Energy Materials the widest study on what happens during battery failure, focusing on the different parts of a battery at the same time. The role of the ESRF was crucial for its success.

We have all experienced it: you have charged your mobile phone and after a short period using it, the battery goes down unusually quickly. Consumer electronics seem to lose power at uneven rates and this is due to the heterogeneity in batteries. When the phone is charging, the top layer charges first and the bottom layer charges later. The mobile phone may indicate it’s complete when the top surface level is finished charging, but the bottom will be undercharged. If you use the bottom layer as your fingerprint, the top layer will be overcharged and will have safety problems.
The truth is, batteries are composed of many different parts that behave differently. Solid polymer helps hold particles together, carbon additives provide electrical connection, and then there are the active battery particles storing and releasing the energy.
An international team of scientists from ESRF, SLAC, Virginia Tech and Purdue University wanted to understand and quantitatively define what leads to the failure of lithium-ion batteries. Until then, studies had either zoomed in on individual areas or particles in the cathode during failure or zoomed out to look at cell level behavior without offering sufficient microscopic details. Now this study provides the first global view with unprecedented amount of microscopic structural details to complement the existing studies in the battery literature.

>Read more on the ESRF website

Improving engine performance and fuel efficiency

A study conducted in part at the Canadian Light Source (CLS) at the University of Saskatchewan suggests reformulating lubricating oils for internal combustion engines could significantly improve not only the life of the oil but the life of the engine too.
Dr. Pranesh Aswath with the Department of Materials Science and Engineering at the University of Texas at Arlington and his research colleagues focused on the role soot plays in engine wear, and its effect on the stability of engine oil.
He described the research as “one piece of a broader story we’re trying to write” about how the reformulation of engine oils can reduce emissions, decrease wear and increase the longevity of engines.
Soot is a carbon-based material that results from incomplete combustion of fuel in an internal combustion engine, he explained. The soot ends up in crankcase oil where it is trapped by additives, but that leads to reduced engine efficiency and a breakdown of lubricating oil.

>Read more on the Canadian Light Source website