Tesla’s advanced battery research group in Canada in partnership with Dalhousie University has released a new paper on a new nickel-based battery that could last 100 years while still favorably comparing to LFP cells on charging and energy density.
Back in 2016, Tesla established its “Tesla Advanced Battery Research” in Canada through a partnership with Jeff Dahn’s battery lab at Dalhousie University in Halifax, Canada.
Dahn is considered a pioneer in Li-ion battery cells. He has been working on the Li-ion batteries pretty much since they were invented. He is credited for helping to increase the life cycle of the cells, which helped their commercialization.
His work now focuses mainly on a potential increase in energy density and durability, while also decreasing the cost.
One of those new leaders, Michael Metzger, along with Dahn himself, and a handful of PhDs in the program, are named as authors of a new research paper called “Li[Ni0.5Mn0.3Co0.2]O2 as a Superior Alternative to LiFePO4 for Long-Lived Low Voltage Li-Ion Cells” in the Journal of the Electrochemical Society.
The paper describes a nickel-based battery chemistry meant to compete with LFP battery cells on longevity while retaining the properties that people like in nickel-based batteries, like higher energy density, which enables longer range with fewer batteries for electric vehicles.
The group wrote in the paper’s abstract:
Single crystal Li[Ni0.5Mn0.3Co0.2]O2//graphite (NMC532) pouch cells with only sufficient graphite for operation to 3.80 V (rather than ≥4.2 V) were cycled with charging to either 3.65 V or 3.80 V to facilitate comparison with LiFePO4//graphite (LFP) pouch cells on the grounds of similar maximum charging potential and similar negative electrode utilization. The NMC532 cells, when constructed with only sufficient graphite to be charged to 3.80 V, have an energy density that exceeds that of the LFP cells and a cycle-life that greatly exceeds that of the LFP cells at 40 °C, 55 °C and 70 °C. Excellent lifetime at high temperature is demonstrated with electrolytes that contain lithium bis(fluorosulfonyl)imide (LiFSI) salt, well beyond those provided by conventional LiPF6 electrolytes.
The cells showed an impressive capacity retention over a high number of cycles:
The research group even noted that the new cell described in the paper could last a 100 years if the temperature is controlled at 25C:
Ultra-high precision coulometry and electrochemical impedance spectroscopy are used to complement cycling results and investigate the reasons for the improved performance of the NMC cells. NMC cells, particularly those balanced and charged to 3.8 V, show better coulombic efficiency, less capacity fade and higher energy density compared to LFP cells and are projected to yield lifetimes approaching a century at 25 °C.
One of the keys appears to be using an electrolyte with LiFSI lithium salts, and the paper notes that the benefits could also apply to other nickel-based chemistries, including those with no or low cobalt.
MIT Researchers build a portable desalination unit that generates clear, clean drinking water without the need for filters or high-pressure pumps.
MIT researchers have developed a portable desalination unit, weighing less than 10 kilograms, that can remove particles and salts to generate drinking water.
The suitcase-sized device, which requires less power to operate than a cell phone charger, can also be driven by a small, portable solar panel, which can be purchased online for around $50. It automatically generates drinking water that exceeds World Health Organization quality standards. The technology is packaged into a user-friendly device that runs with the push of one button.
Unlike other portable desalination units that require water to pass through filters, this device utilizes electrical power to remove particles from drinking water. Eliminating the need for replacement filters greatly reduces the long-term maintenance requirements.
This could enable the unit to be deployed in remote and severely resource-limited areas, such as communities on small islands or aboard seafaring cargo ships. It could also be used to aid refugees fleeing natural disasters or by soldiers carrying out long-term military operations.
“This is really the culmination of a 10-year journey that I and my group have been on. We worked for years on the physics behind individual desalination processes, but pushing all those advances into a box, building a system, and demonstrating it in the ocean, that was a really meaningful and rewarding experience for me,” says senior author Jongyoon Han, a professor of electrical engineering and computer science and of biological engineering, and a member of the Research Laboratory of Electronics (RLE).
Joining Han on the paper are first author Junghyo Yoon, a research scientist in RLE; Hyukjin J. Kwon, a former postdoc; SungKu Kang, a postdoc at Northeastern University; and Eric Brack of the U.S. Army Combat Capabilities Development Command (DEVCOM). The research has been published online in Environmental Science and Technology.
Commercially available portable desalination units typically require high-pressure pumps to push water through filters, which are very difficult to miniaturize without compromising the energy-efficiency of the device, explains Yoon.
Instead, their unit relies on a technique called ion concentration polarization (ICP), which was pioneered by Han’s group more than 10 years ago. Rather than filtering water, the ICP process applies an electrical field to membranes placed above and below a channel of water. The membranes repel positively or negatively charged particles — including salt molecules, bacteria, and viruses — as they flow past. The charged particles are funneled into a second stream of water that is eventually discharged.
The process removes both dissolved and suspended solids, allowing clean water to pass through the channel. Since it only requires a low-pressure pump, ICP uses less energy than other techniques.
But ICP does not always remove all the salts floating in the middle of the channel. So the researchers incorporated a second process, known as electrodialysis, to remove remaining salt ions.
Yoon and Kang used machine learning to find the ideal combination of ICP and electrodialysis modules. The optimal setup includes a two-stage ICP process, with water flowing through six modules in the first stage then through three in the second stage, followed by a single electrodialysis process. This minimized energy usage while ensuring the process remains self-cleaning.
“While it is true that some charged particles could be captured on the ion exchange membrane, if they get trapped, we just reverse the polarity of the electric field and the charged particles can be easily removed,” Yoon explains.
They shrunk and stacked the ICP and electrodialysis modules to improve their energy efficiency and enable them to fit inside a portable device. The researchers designed the device for nonexperts, with just one button to launch the automatic desalination and purification process. Once the salinity level and the number of particles decrease to specific thresholds, the device notifies the user that the water is drinkable.
The researchers also created a smartphone app that can control the unit wirelessly and report real-time data on power consumption and water salinity.
After running lab experiments using water with different salinity and turbidity (cloudiness) levels, they field-tested the device at Boston’s Carson Beach.
Yoon and Kwon set the box near the shore and tossed the feed tube into the water. In about half an hour, the device had filled a plastic drinking cup with clear, drinkable water.
“It was successful even in its first run, which was quite exciting and surprising. But I think the main reason we were successful is the accumulation of all these little advances that we made along the way,” Han says.
The resulting water exceeded World Health Organization quality guidelines, and the unit reduced the amount of suspended solids by at least a factor of 10. Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watts of power per liter.
“Right now, we are pushing our research to scale up that production rate,” Yoon says.
One of the biggest challenges of designing the portable system was engineering an intuitive device that could be used by anyone, Han says.
Yoon hopes to make the device more user-friendly and improve its energy efficiency and production rate through a startup he plans to launch to commercialize the technology.
In the lab, Han wants to apply the lessons he’s learned over the past decade to water-quality issues that go beyond desalination, such as rapidly detecting contaminants in drinking water.
“This is definitely an exciting project, and I am proud of the progress we have made so far, but there is still a lot of work to do,” he says.
For example, while “development of portable systems using electro-membrane processes is an original and exciting direction in off-grid, small-scale desalination,” the effects of fouling, especially if the water has high turbidity, could significantly increase maintenance requirements and energy costs, notes Nidal Hilal, professor of engineering and director of the New York University Abu Dhabi Water research center, who was not involved with this research.
“Another limitation is the use of expensive materials,” he adds. “It would be interesting to see similar systems with low-cost materials in place.”
The research was funded, in part, by the DEVCOM Soldier Center, the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), the Experimental AI Postdoc Fellowship Program of Northeastern University, and the Roux AI Institute.
Batteries power our lives by transforming energy from one type to another.
Whether a traditional disposable battery (e.g. AA) or a rechargeable lithium-ion battery (used in cell phones, laptops and cars), a battery stores chemical energy and releases electrical energy.
There are four key parts in a battery — the cathode (positive side of the battery), the anode (negative side of the battery), a separator that prevents contact between the cathode and anode and a chemical solution known as an electrolyte that allows the flow of electrical charge between the cathode and anode.
Lithium-ion batteries that power cell phones, for example, typically consist of a cathode made of cobalt, manganese, and nickel oxides and an anode made out of graphite, the same material found in many pencils. The cathode and anode store the lithium.
When a lithium-ion battery is turned on, positively charged particles of lithium (ions) move through the electrolyte from the anode to cathode. Chemical reactions occur that generate electrons and convert stored chemical energy in the battery to electrical current.
When you plug in your cell phone to charge the lithium-ion battery, the chemical reactions go in reverse: the lithium ions move back from the cathode to the anode.
As long as lithium ions shuttle back and forth between the anode and cathode, there is a constant flow of electrons. This provides the energy to keep your devices running. Since this cycle can be repeated hundreds of times, this type of battery is rechargeable.
A lithium-ion battery is a type of rechargeable battery. It has four key parts:
1The cathode (the positive side), typically a combination of nickel, manganese and cobalt oxides.
2The anode (the negative side), commonly made out of graphite, the same material found in many pencils.
3A separator that prevents contact between the anode and cathode.
4A chemical solution known as an electrolyte that moves lithium ions between the cathode and anode. The anode and cathode store lithium.
When the battery is in use, positively charged particles of lithium (ions) move through the electrolyte from the anode to cathode. Chemical reactions occur that generate electrons and convert stored chemical energy in the battery to electrical current.
When the battery is charging, the chemical reactions go in reverse: the lithium ions move back from the cathode to the anode.
Batteries and the U.S. Department of Energy’s (DOE) Argonne National Laboratory
Argonne is recognized as a global leader in battery science and technology. Over the past sixty years, the lab’s pivotal discoveries have strengthened the U.S. battery manufacturing industry, aided the transition of the U.S. automotive fleet toward plug-in hybrid and electric vehicles, and enabled greater use of renewable energy, such as wind and solar power.
Argonne researchers are also exploring how to accelerate the recycling of lithium-ion batteries through the DOE’s ReCell Center, a collaboration led by Argonne that includes the National Renewable Energy Laboratory, Oak Ridge National Laboratory, as well as Worcester Polytechnic Institute, University of California at San Diego and Michigan Technological University.
For another take on “Batteries 101,” check out DOE Explains.
EPFL’s Blue Brain Project has found a way to use only mathematics to automatically draw neurons in 3D, meaning we are getting closer to being able to build digital twins of brains.
Santiago Ramón y Cajal, a Spanish physician from the turn of the 19th century, is considered by most to be the father of modern neuroscience. He stared down a microscope day and night for years, fascinated by chemically stained neurons he found in slices of human brain tissue.
By hand, he painstakingly drew virtually every new type of neuron he came across using nothing more than pen and paper. As the Charles Darwin for the brain, he mapped every detail of the forest of neurons that make up the brain, calling them the “butterflies of the brain.”
Today, 200 years later, Blue Brain has found a way to dispense with the human eye, pen and paper, and use only mathematics to automatically draw neurons in 3D as digital twins. Math can now be used to capture all the “butterflies of the brain,” which allows us to use computers to build any and all the billons of neurons that make up the brain. And that means we are getting closer to being able to build digital twins of brains.
These billions of neurons form trillions of synapses—where neurons communicate with each other. Such complexity needs comprehensive neuron models and accurately reconstructed detailed brain networks in order to replicate the healthy and disease states of the brain. Efforts to build such models and networks have historically been hampered by the lack of experimental data available.
But now, scientists at the EPFL Blue Brain Project using algebraic topology, a field of Math, have created an algorithm that requires only a few examples to generate large numbers of unique cells. Using this algorithm—the Topological Neuronal Synthesis (TNS), they can efficiently synthesize millions of unique neuronal morphologies.
The TNS algorithm is of huge importance for the rapidly growing field of computational neuroscience, which increasingly relies on biologically-realistic models from the single cell level to large-scale neuronal networks. Accurate neuronal morphologies, in particular, lie at the heart of these efforts as they are essential for defining cell types, discerning their functional roles, investigating structural alterations associated with diseased brain states and, identifying what conditions make brain networks sufficiently robust to support the complex cortical processes that are fundamental for a healthy brain.
Therefore, it is essential to accurately reconstruct detailed brain networks in order to replicate the healthy and disease states of the brain.
In a paper published in Cell Reports, a team led by Lida Kanari has applied the Topological Morphology Descriptor (TMD) introduced in Kanari et al. 2018, which reliably categorizes dendritic morphologies, to digitally synthesize dendritic morphologies from all layers and morphological types of the rodent cortex. The advantages of this topology-driven approach are multiple, as the new TNS algorithm, is generalizable to new types of cells, needs little input data and does not require fine tuning because it captures feature correlations.
Enabling the rapid digital reconstruction of entire brain regions from relatively few reference cells
The TNS algorithm driven by the topological architecture of dendrites generates realistic morphologies for a large number of distinct cortical neuronal cell types with realistic morphological and electrical properties. This has enabled the rapid digital reconstruction of entire brain regions from relatively few reference cells, thereby allowing the investigation of links between neuronal morphologies and brain function across different spatio-temporal scales and addressing the challenge of insufficient biological reconstructions.
A multi-stage validation documented in the paper ensures that the synthesized cells reproduce the shapes of reconstructed neurons with respect to three modalities: 1. Their morphological characteristics, 2. The electrical activity of single cells and, 3. The connectivity of the network they form.
Lida Kanari explains that “the findings are already enabling Blue Brain to build biologically detailed reconstructions and simulations of the mouse brain, by computationally reconstructing brain regions for simulations which replicate the anatomical properties of neuronal morphologies and include region specific anatomy. We address one of the fundamental problems for neuroscience—the scarcity of experimental neuronal reconstructions since the topological synthesis requires only a few examples to generate large numbers of unique cells. Using the TNS algorithm, we can efficiently synthesize millions of unique neuronal morphologies (10 million cells in a few hours),” she concludes.
Facilitating medical applications
“Comprehensive neuron models are essential for defining cell types, discerning their functional roles and investigating structural alterations associated with diseased brain states,” affirms Blue Brain Founder and Director, Prof. Henry Markram. “The researchers synthesized cortical networks based on structural alterations of dendrites associated with medical conditions and revealed principles linking branching properties to the structure of large-scale networks.”
“As the TNS algorithm is implemented in an open source software, this will allow the modeling of brain diseases in terms of single cells and networks, as it provides a tool to directly investigate the link between local morphological properties and the connectivity of the neuronal network they form. This approach is of particular interest for medical applications as it enables the investigation of diseases in terms of the emergence of global network pathology from local structural changes in neuron morphologies,” he concludes.
** Note to Readers: With more than a few ‘dental people connections’ in the family, please indulge us this ‘nano-departure’ from our normal Posts on Renewable Energy (Green Hydrogen, Nano-Enhanced Battery Materials & Storage), Nano-Bio Medicine (Nano-Enhanced Cancer Research & Treatment) and Water Treatment (Nano-Enhanced Membranes and Nanoparticles). We hope you can “sink your teeth” into these amazing advances in Technology making our lives a little better. – Team GNT
A Dental Story
Reggie falls and loses two of his teeth. He soon finds it difficult to chew correctly and realizes he might visit the dentist for implants. Coincidentally, his grandmother had to get implants years ago. He remembers how they had to take multiple visits to the dentist and how long it took to fix her smile. Ultimately, Reggie gets discouraged and postpones his visit to the dentist.
This story typically depicts one of the drawbacks of traditional dental procedures, which has been corrected by technological advancements in dentistry over the years. Most dental experts today, like the dentist Steven Shapiro, DMD attests to the benefits of advanced technology such as nanotechnology and robotics in dental surgeries and procedures.
It has also been established that, because of these innovations, there is higher accuracy in surgeries, reducing the risk of complications which is a big win for the dental industry today. This is not to mention the increased convenience for the patient. So, Reggie might not have to wait that long to get his dental implants anymore.
Here are some of the technology innovations that have rocked the world of dentistry over the years.
Navigation surgery in dental procedures is associated with better accuracy, improved reliability, and convenience. These techniques are often linked with imaging systems like cone-beam computed tomography. This ensures better safety as compared with conventional dental procedures. There’s also a generally reduced failure rate, especially for dental implants, since less invasive methods are used. Therefore, there’s an increased success rate of such surgeries and fewer major complications.
Robotics-assisted dental surgeries
Advanced artificial intelligence in robotics is now used in navigational surgery for many dental procedures such as implant treatment periodontics, orthodontics, endodontics, and so much more. Increased precision and better dental care are made available using robotics over traditional freehand techniques. Dental clinicians can also use artificial intelligence to create new methods of diagnosing and treatment.
Complications of traditional implant surgery vs use of robotics
Several things could go wrong during implant surgery. These include:
Injuries are caused by incision or perforation of the lingual plate, inferior border, inferior alveolar canal, and so on;
Tissue necrosis or death;
Implant Dehiscence defect; and
Damage to a nerve.
The above kinds of injury can cause complications and severe infections. Other factors can lead to complications such as lack of adequate dental expertise, patient-related or underlying conditions, and implant location.
A surgical guide should help the dentist navigate during traditional dental surgeries, but there could be specific errors, such as fitting and angulation. With robotics, the clinician can change direction during the implant procedure, unlike surgical guides, which don’t allow any adjustments. Other benefits of using robotics in surgical implant treatment are:
Imaging during the preoperative phase to enable the dentist properly views the anatomical features.
It hands over control to the dentist after its job is done.
It makes use of sensory feedback for correct angulation and positioning.
It provides navigational guidance to the dental clinician.
It is more convenient for the patient.
Use of microrobots
Microrobots can be used in endodontic therapy. In this procedure, the microrobot is placed on the tooth. It carries out the root canal procedure, including cleaning and drilling, to reduce errors and improve the reliability of the process.
Nanotechnology is simply the branch of engineering and technology concerned with building and designing nanobots. These nanobots are tiny machines that can interact with specific cells in the body. This interaction can lead to changes in treatment delivery and overall therapeutic effect.
Nano dentistry is the application of nanotechnology in the field of dentistry. Due to its small size(nanometers), it is used at the cellular or molecular level to manage all complicated cases and reduce the failure rate of dental procedures. Nanotech is used in restorative surgeries, periodontics, bone replacement, and drug delivery.
More beneficial than conventional methods
In summary, artificial intelligence and nanotechnology are more beneficial than conventional methods but are slowly used in dentistry compared to other areas of medicine. Dentists must play a massive role in adopting these techniques and increasing their knowledge about these technological advancements.
Since the goal of patient care is optimum treatment, tech advancements have been proven to provide a better quality of treatment and are worth giving a shot. Conventional dental procedures are time-consuming and are also largely inconvenient.
Still, technology can take all these disadvantages away by saving time, improving precision and accuracy, improving reliability, reduce complications and failure rates for dental procedures.
Energy storage in lithium-sulfur batteries is potentially higher than in lithium-ion batteries but they are hampered by a short life. Researchers from Uppsala University in Sweden have now identified the main bottlenecks in performance.
Lithium-sulfur batteries are high on the wish-list for future batteries as they are made from cheaper and more environmentally friendly materials than lithium-ion batteries. They also have higher energy storage capacity and work well at much lower temperatures. However, they suffer from short lifetimes and energy loss. An article just published in the journal Chem by a research group from Uppsala University has now identified the processes that are limiting the performance of the sulfur electrodes that in turn reduces the current that can be delivered. Various different materials are formed during the discharge/charge cycles and these cause various problems. Often a localized shortage of lithium causes a bottleneck.
“Learning about problems allows us to develop new strategies and materials to improve battery performance. Identifying the real bottlenecks is needed to take the next steps. This is big research challenge in a system as complex as lithium-sulfur,” says Daniel Brandell, Professor of Materials Chemistry at Uppsala University who works at the Ångström Advanced Battery Centre.
The study combined various radiation scattering techniques: X-ray analyses were made in Uppsala, Sweden and neutron results came from a large research facility, the Institut Laue Langevin, in Grenoble, France.
“The study demonstrates the importance of using these infrastructures to tackle problems in materials science,” says Professor Adrian Rennie. “These instruments are expensive but are necessary to understand such complex systems as these batteries. Many different reactions happen at the same time and materials are formed and can disappear quickly during operation.”
The study was carried-out as part of a co-operation with Scania CV AB.
“Electric power is needed for the heavy truck business and not just personal vehicles. They must keep up with developments of a range of different batteries that may soon become highly relevant,” says Daniel Brandell.
Could this audacious electric scooter be the Honda Cub of the 21st Century? Ola is betting big on the S1
Ola is building the world’s largest motorcycle “Futurefactory,” and planning a staggeringly massive push into India’s electric scooter market. It has now made a “multi-million dollar investment” in an ultra-fast charging battery company from Israel.
Part of that rock-bottom price comes from serious volume; Ola is building the biggest motorcycle factory in history. The Futurefactory under construction now is a colossal, 500-acre, carbon-negative production complex that will be capable of pouring out up to an astonishing 10 million bikes per year once it reaches full capacity – that’s around 15 percent of the entire current global motorcycle production run. So there’s enormous hopes and dreams behind these scoots, and considerable pressure to get the S1 right.
Now, it seems Ola has made a move that could give its bikes some extreme fast-charging capabilities.
The company has made a “multi-million dollar investment” in Israel’s StoreDot, which makes it a “strategic partner” and will allow it to “incorporate and manufacture StoreDot’s fast charging technologies for future vehicles in India.”
Ola’s Futurefactory, now under construction, will be the world’s largest motorcycle manufacturing plant, capable of building 10 million bikes a year
StoreDot claims that its nanodot-enhanced, silicon-dominant anode, XFC lithium-ion cells will go into mass manufacture in 2024 as pouch cells and 4680-family cylinder cells, and they’ll initially be able to deliver 100 miles (160 km) of scooter range in a 5-minute charge, with an impressive 300 Wh/kg specific energy – considerably more energy-dense than today’s state of the art commercial cells.
Its second-gen solid-state cells, slated for 2028, promise a sky-high 450 Wh/kg, so they’ll be significantly lighter, as well as even faster to charge – StoreDot claims 100 miles in 3 minutes.
And in 10 years’ time, the company says it’s got plans for a “post-lithium” design capable of 100-mile charges in 2 minutes, with a monstrous 550 Wh/kg of energy on board. Such is the “clear, hype-free technology roadmap” that StoreDot CEO Doron Myersdorf promises partners.
“The future of EVs lies in better, faster and high energy density batteries, capable of rapid charging and delivering higher range,” said Ola founder and CEO Bhavish Aggarwal in a press release. “We are increasing our investments in core cell and battery technologies and ramping up our in-house capabilities and global talent hiring, as well as partnering with global companies doing cutting edge work in this field. Our partnership with StoreDot, a pioneer of extreme fast charging battery technologies, is of strategic importance and a first of many.”
It all sounds great, but the big unknown here is whether StoreDot will actually finally deliver on its fast-charge battery promises.
The company has been sending sample batteries to EV manufacturers for testing. “We are not releasing a lab prototype,” Myersdorf told The Guardian in January 2021. “We are releasing engineering samples from a mass production line.
This demonstrates it is feasible and it’s commercially ready.” And yet the nanodot technology in these samples was based on highly expensive germanium, rather than the cheap and widely available silicon, indicating that it was perhaps not quite ready.
Still, StoreDot has taken on at least US$190 million in investments and formed similar strategic partnerships with companies including VinFast, BP, Daimler, Samsung, TDK and Eve Energy – so along with Ola Electric, plenty of serious players have liked what they’ve seen enough to put their money on the line. Last November, StoreDot announced that Eve Energy had managed to produce “A-series samples” of the silicon-dominant batteries in a factory in China.
We’d all like to see EV charge times drop to the level where a top-up takes no longer than filling a tank of gas. Will StoreDot be the company that makes that a reality? Stay tuned!
In an article available as a pre-proof in the journal Carbon, researchers used electrospinning methodologies to develop an air cathode built of self-sustaining nitrogen-doped reduced graphene oxide@carbon nanofiber (N rGO@CNF) hybrid sheets suitable for microbial fuel cells.
Microbial Fuel Cells for Bioenergy Production
It is critical to develop eco-friendly and sustainable technology in light of rising climate change consequences and global energy demand.
Microbial fuel cells (MFCs), a developing biological electrolytic system with good prospects as a maintainable bioenergy generation system, have piqued scientists’ curiosity for the past few years since they can concurrently produce electricity as well as treat water waste by transforming chemical energy contained in organic material to electricity with the help of microbes and fuel (usually wastewater).
MFC outperforms alternative methods for producing energy from biological material in terms of operating and functional characteristics, such as excellent direct effectiveness, ambient temperature functioning, and no need for supplementary energy or gas treatment.
Composition of a Typical MFC
The organic materials undergo oxidation in the anode compartment, generating protons and electrons. The electrons then move via an exterior circuit, yielding electrical energy, whereas the protons move to the cathode compartment via the electrolyte, in which they interact with the electron acceptors (O2). This results in the oxygen reduction reaction (ORR), which produces water using a two-electron or four-electron mechanism.
The electron receptors in the cathodic chamber have a critical role in energy production via microbial fuel cells; oxygen from the air is the best electron recipient because it is readily available and inexpensive. Since the slow ORR conducted in the cathodic chamber is considered the main hurdle, and improving ORR may considerably boost the total MFC effectiveness, MFC output is highly reliant on electrode performance, particularly that of the cathode.
** Graphical Abstract
How to Improve Performance of Air Cathode in MFCs
In a singular chambered microbial fuel cell, the typical air cathode comprises of three parts: the catalytic layer (CL), the substrate or the supporting layer (SL), and the conducting gas diffusion layer (GDL). Since the effectiveness of the air cathode is mostly determined by the catalytic layer, substantial research into catalyst designing and development has been carried out to enhance ORR taking place in the air cathode.
Thanks to their high catalysis performance, composites based on platinum (Pt) are currently the most widely utilized catalytic materials, but their industrial applications have been restricted by their significant prices, limited availability, and vulnerability to deactivation induced by biofouling and poisons in MFC settings.
Carbonaceous materials have come to the fore as excellent air cathode catalytic materials for microbial fuel cells as compared to platinum and other metallic catalysts, owing to their inexpensive prices, great stability, toxin tolerance, and excellent catalysis performance in ORR, making them viable substitutes to Pt-based catalysts.
Influence of Heteroatom Doping
One of the most successful ways for improving the ORR performance of carbonaceous materials has been established to be heteroatom doping. Injecting nitrogen (N) into the carbon framework activates electrons by creating charge spots, resulting in increased ORR catalysis performance.
Owing to the ease of agglomeration of carbon-based nanomaterials, which can obstruct catalytically active spots, the ORR effectiveness of carbonaceous composites doped with heteroatoms is still not optimal. Reduced graphene oxide (rGO) is presently utilized as an alternative form of carbon-based material to produce carbon-carbon hybrids for ORR usage. The blend of rGO and N-injected nanocarbons has a higher conductance, meaning more active spots for ORR are available.
Key Findings of the Study
In this paper, self-sustaining N-injected rGO@CNF hybridized membranes were effectively constructed using an electrospinning approach involving the addition of graphene oxide to a polyacrylonitrile (PAN) mixture followed by thermal processing in an NH3 setting.
The constructed rGO@CNFs can be used as embedded cathodes in microbial fuel cells directly. Their architectures, make-up, and texture were studied, as well as their electrolytic characteristics and MFC effectiveness, which were examined against pure NCNF and CAC electrodes.
The test results showed that rGO@CNFs outperformed the pure NCNF and CAC in terms of MFC effectiveness and ORR activation. In addition, the quantity of rGO incorporated in CNF had a significant impact on ORR activity and MFC effectiveness. On the basis of these findings, electrospun self-sustaining rGO@CNF hybridized membranes are suggested to be viable direct cathode options in MFCs.
Ionic liquids give push to next-gen solid-state lithium metal batteries. Credit: Tokyo Metropolitan University
Since their first commercialization, rechargeable Li-ion batteries have dominated the portable electronicsmarket for the last three decades. But as we look for better solutions with higher energy density, scientists have been turning to solid-state lithium metal batteries.
Li metal batteries potentially have a much higher energy density than their Li-ion counterparts, but technical issues keep solid-state lithium metal batteries from making their way into demanding applications. It is difficult to achieve good contact between electrodes and solid electrolytes. Any surface roughness on either side leads to high interfacial resistance, which plagues battery performance.
Researchers at Japan’s Tokyo Metropolitan University have been developing new ways of improving the contact between the cathode and solid-state electrolyte in solid-state lithium metal batteries. And now, they have succeeded in creating a new quasi-solid-state cathode, with significantly reduced problematic resistance between key components. The new quasi-solid-state lithium cobalt oxide (LiCoO2) cathode contains a room-temperature ionic liquid, which is salt in a liquid state.
By adding an ionic liquid, their modified cathode could maintain excellent contact with the electrolyte.
The addition of an ionic liquid to the cathode material fills structural voids and provides a better interface with the solid electrolyte. Credit: Tokyo Metropolitan University
Ionic liquids consist of positive and negative ions; they can also transport ions and fill tiny voids at the cathode and the solid electrolyte interface. With the voids filled, the interfacial resistance was significantly reduced. Ionic liquids are not only ionically conductive but almost non-volatile and usually non-flammable.
The team demonstrated a prototype battery featuring this novel, quasi-solid-state cathode that showed impressive stability, with 80% capacity retention after 100 charge and discharge cycles at an elevated temperature of 60°C.
Though finding a better ionic liquid that doesn’t degrade as easily remains challenging, the idea promises new directions in solid lithium battery development for practical applications.
Materials scientists at the UCLA Samueli School of Engineering and colleagues from five other universities around the world have discovered the major reason why perovskite solar cells — which show great promise for improved energy-conversion efficiency — degrade in sunlight, causing their performance to suffer over time.
The team successfully demonstrated a simple manufacturing adjustment to fix the cause of the degradation, clearing the biggest hurdle toward the widespread adoption of the thin-film solar cell technology.
A research paper detailing the findings was published in Nature. The research is led by Yang Yang, a UCLA Samueli professor of materials science and engineering and holder of the Carol and Lawrence E. Tannas, Jr., Endowed Chair. The co-first authors are Shaun Tan and Tianyi Huang, both recent UCLA Samueli Ph.D. graduates whom Yang advised.
Perovskites are a group of materials that have the same atomic arrangement or crystal structure as the mineral calcium titanium oxide. A subgroup of perovskites, metal halide perovskites, are of great research interest because of their promising application for energy-efficient, thin-film solar cells.
Perovskite-based solar cells could be manufactured at much lower costs than their silicon-based counterparts, making solar energy technologies more accessible if the commonly known degradation under long exposure to illumination can be properly addressed. For further information see the IDTechEx report on Energy Harvesting Microwatt to Gigawatt: Opportunities 2020-2040.
“Perovskite-based solar cells tend to deteriorate in sunlight much faster than their silicon counterparts, so their effectiveness in converting sunlight to electricity drops over the long term,” said Yang, who is also a member of the California NanoSystems Institute at UCLA. “However, our research shows why this happens and provides a simple fix. This represents a major breakthrough in bringing perovskite technology to commercialization and widespread adoption.”
A common surface treatment used to remove solar cell defects involves depositing a layer of organic ions that makes the surface too negatively charged. The UCLA-led team found that while the treatment is intended to improve energy-conversion efficiency during the fabrication process of perovskite solar cells, it also unintentionally creates a more electron-rich surface — a potential trap for energy-carrying electrons.
This condition destabilizes the orderly arrangement of atoms, and over time the perovskite solar cells become increasingly less efficient, ultimately making them unattractive for commercialization.
Armed with this new discovery, the researchers found a way to address the cells’ long-term degradation by pairing the positively charged ions with negatively charged ones for surface treatments. The switch enables the surface to be more electron-neutral and stable, while preserving the integrity of the defect-prevention surface treatments.
The team tested the endurance of their solar cells in a lab under accelerated ageing conditions and 24/7 illumination designed to mimic sunlight. The cells managed to retain 87% of their original sunlight-to-electricity conversion performance for more than 2,000 hours. For comparison, solar cells manufactured without the fix dropped to 65% of their original performance after testing over the same time and conditions.
“Our perovskite solar cells are among the most stable in efficiency reported to date,” Tan said. “At the same time, we’ve also laid new foundational knowledge, on which the community can further develop and refine our versatile technique to design even more stable perovskite solar cells.”