GT/ Cobalt-free battery for cleaner, greener power
Energy & green technology biweekly vol.59, 17th October — 3rd November
TL;DR
- High-capacity and reliable rechargeable batteries are a critical component of many devices and even modes of transport. They play a key role in the shift to a greener world. A wide variety of elements are used in their production, including cobalt, the production of which contributes to some environmental, economic, and social issues. A team now presents a viable alternative to cobalt which in some ways can outperform state-of-the-art battery chemistry. It also survives a large number of recharge cycles, and the underlying theory can be applied to other problems.
- A huge step forward in the evolution of perovskite solar cells will have significant implications for renewable energy development.
- Power grids — the web of electrical networks that sprawl across countries and continents — are under stress. Extreme weather events and volatile energy demands often push the system to the brink. Although these high-impact events can be very damaging, often overlooked is the impact of minor disruptions that trigger a domino effect throughout the system, according to a study analyzing European power blackouts. The findings showed that recovering power within 13 hours can reduce up to 52% of the power loss stemming from cascading events.
- The world may have crossed a ‘tipping point’ that will inevitably make solar power our main source of energy, new research suggests.
- Engineers have designed a system that can efficiently produce ‘solar thermochemical hydrogen.’ It harnesses the sun’s heat to split water and generate hydrogen — a clean fuel that emits no greenhouse gas emissions.
- Research reveals that recycling post-use plastic through pyrolysis can reduce GHG emissions by 18–23%. Approach can potentially enhance sustainability by minimizing waste and fossil resource reliance.
- Researchers are now presenting a new and efficient way to recycle metals from spent electric car batteries. The method allows recovery of 100 per cent of the aluminum and 98 per cent of the lithium in electric car batteries. At the same time, the loss of valuable raw materials such as nickel, cobalt and manganese is minimized. No expensive or harmful chemicals are required in the process because the researchers use oxalic acid — an organic acid that can be found in the plant kingdom.
- Lithium–sulfur batteries (LSBs) offer a higher energy storage potential. However, issues like formation of lithium polysulfides and lithium dendrites lead to capacity loss and raise safety concerns. Now, researchers have developed a graphene separator embedded with platinum-doped gold nanoclusters, which enhance lithium-ion transport and facilitate redox reactions. This breakthrough addresses the long-standing issues associated with LSBs, setting the stage for their commercialization.
- Filtration systems are designed to capture multiple harmful substances from water or air simultaneously, but pollutants in soil can only be tackled individually or a few at a time — at least for now. A new method could help turn soil remediation processes from piecemeal to wholesale.
- A research study tackled the critical issue of how city-scale building energy consumption in urban environments will evolve under the influence of climate change.
- And more!
Green Technology Market
Green technology is an applicable combination of advanced tools and solutions to conserve natural resources and environment, minimize or mitigate negative impacts from human activities on the environment, and ensure sustainability development. Green technology is also referred to as clean technology or environmental technology which includes technologies, such as IoT, AI, analytics, blockchain, digital twin, security, and cloud, which collect, integrate, and analyze data from various real-time data sources, such as sensors, cameras, and Global Positioning System (GPS).
Green technology, also known as sustainable technology, protects the environment by using various forms of sustainable energy. Some of the best examples of green technologies include solar panels, LED lighting, wind energy, electric vehicles, vertical farming, and composting.
The global Green Technology and Sustainability market size to grow from USD 11.2 billion in 2020 to USD 36.6 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 26.6% during the forecast period. The growing consumer and industrial interest for the use of clean energy resources to conserve environment and increasing use of Radio Frequency Identification sensors across industries are driving the adoption of green technology and sustainability solutions and services in the market.
The blockchain segment is estimated to grow at the highest CAGR: Energy-intensive cryptocurrency mining has caused a spike in carbon emission, and hence blockchain is capable of driving innovation in the field of green technology.
Latest Research
Electrolyte design for lithium-ion batteries with a cobalt-free cathode and silicon oxide anode
by Seongjae Ko, Xiao Han, Tatau Shimada, Norio Takenaka, Yuki Yamada, Atsuo Yamada in Nature Sustainability
High-capacity and reliable rechargeable batteries are a critical component of many devices and even modes of transport. They play a key role in the shift to a greener world. A wide variety of elements are used in their production, including cobalt, the production of which contributes to some environmental, economic, and social issues. For the first time, a team including researchers from the University of Tokyo presents a viable alternative to cobalt which in some ways can outperform state-of-the-art battery chemistry. It also survives a large number of recharge cycles, and the underlying theory can be applied to other problems.
The chances are, you are reading this article on a laptop or smartphone, and if not, you probably own at least one of those. Inside either device, and many others, you will find a lithium-ion battery (LIB). For decades now, LIBs have been the standard way of powering portable or mobile electronic devices and machines. As the world transitions from fossil fuels, they are seen as an important step for use in electric cars and home batteries for those with solar panels. But just as batteries have a positive end and a negative end, LIBs have negative points set against their positive ones.
For one thing, although they are some of the most power-dense portable power sources available, many people wish that LIBs could yield a larger energy density to make them either last longer or power even more demanding machines. Also, they can survive a large number of recharge cycles, but they also degrade with time; it would be better for everyone if batteries could survive more recharge cycles and maintain their capacities for longer. But perhaps the most alarming problem with current LIBs lies in one of the elements used for their construction.
Cobalt is widely used for a key part of LIBs, the electrodes. All batteries work in a similar way: Two electrodes, one positive and one negative, promote the flow of lithium ions between them in what’s called the electrolyte when connected to an external circuit. Cobalt, however, is a rare element; so rare in fact that there is only one main source of it at present: a series of mines located in the Democratic Republic of Congo. Many issues have been reported over the years about the environmental consequences of these mines, as well as the labor conditions there, including the use of child labor. From a supply perspective also, the source of cobalt is an issue due to political and economic instability in the region.
“There are many reasons we want to transition away from using cobalt in order to improve lithium-ion batteries,” said Professor Atsuo Yamada from the Department of Chemical System Engineering. “For us the challenge is a technical one, but its impact could be environmental, economic, social and technological. We are pleased to report a new alternative to cobalt by using a novel combination of elements in the electrodes, including lithium, nickel, manganese, silicon and oxygen — all far more common and less problematic elements to produce and work with.”
The new electrodes and electrolyte Yamada and his team created are not only devoid of cobalt, but they actually improve upon current battery chemistry in some ways. The new LIBs’ energy density is about 60% higher, which could equate to longer life, and it can deliver 4.4 volts, as opposed to about 3.2–3.7 volts of typical LIBs. But one of the most surprising technological achievements was to improve upon the recharge characteristics. Test batteries with the new chemistry were able to fully charge and discharge over 1,000 cycles (simulating three years of full use and charging), whilst only losing about 20% of their storage capacity.
“We are delighted with the results so far, but getting here was not without its challenges. It was a struggle trying to suppress various undesirable reactions that were taking place in early versions of our new battery chemistries which could have drastically reduced the longevity of the batteries,” said Yamada. “And we still have some way to go, as there are lingering minor reactions to mitigate in order to improve the safety and longevity even further. At present, we are confident that this research will lead to improved batteries for many applications, but some, where extreme durability and lifespan are required, might not be satisfied just yet.”
Although Yamada and his team were exploring applications in LIBs, the concepts that underlie their recent development can be applied to other electrochemical processes and devices, including other kinds of batteries, water splitting (to produce hydrogen and oxygen), ore smelting, electro-coating and more.
Stabilized hole-selective layer for high-performance inverted p-i-n perovskite solar cells
by Zhen Li, Xianglang Sun, Xiaopeng Zheng, Bo Li, Danpeng Gao, Shoufeng Zhang, Xin Wu, Shuai Li, Jianqiu Gong, Joseph M. Luther, Zhong’an Li, Zonglong Zhu in Science
A huge step forward in the evolution of perovskite solar cells recorded by researchers at City University of Hong Kong (CityU) will have significant implications for renewable energy development. The CityU innovation paves the way for commercialising perovskite solar cells, bringing us closer to an energy-efficient future powered by sustainable sources.
“The implications of this research are far-reaching, and its potential applications could revolutionise the solar energy industry,” said Professor Zhu Zonglong of the Department of Chemistry at CityU, who collaborated with Professor Li Zhong’an at Huazhong University of Science and Technology.
Perovskite solar cells are a promising frontier in the solar energy landscape, known for their impressive power conversion efficiency. However, they have one significant drawback: thermal instability, i.e. they don’t tend to perform well when exposed to high temperatures. The team at CityU has engineered a unique type of self-assembled monolayer, or SAM for short, and anchored it on a nickel oxide surface as a charge extraction layer.
“Our approach has dramatically enhanced the thermal robustness of the cells,” said Professor Zhu, adding that thermal stability is a significant barrier to the commercial deployment of perovskite solar cells.
“By introducing a thermally robust charge extraction layer, our improved cells retain over 90% of their efficiency, boasting an impressive efficiency rate of 25.6%, even after operated under high temperatures, around (65 degrees Celsius) for over 1,000 hours. This is a milestone achievement,” said Professor Zhu.
The motivation for this research was born from a specific challenge in the solar energy sector: the thermal instability of perovskite solar cells.
“Despite their high power conversion efficiency, these solar cells are like a sports car that runs exceptionally well in cool weather but tends to overheat and underperform on a hot day. This was a significant roadblock preventing their widespread use,” said Professor Zhu.
The CityU team has focused on the self-assembled monolayer (SAM), an essential part of these cells, and envisioned it as a heat-sensitive shield that needed reinforcement.
“We discovered that high-temperature exposure can cause the chemical bonds within SAM molecules to fracture, negatively impacting device performance. So our solution was akin to adding a heat-resistant armour — a layer of nickel oxide nanoparticles, topped by a SAM, achieved through an integration of various experimental approaches and theoretical calculations,” Professor Zhu said.
To counteract this issue, the CityU team introduced an innovative solution: anchoring the SAM onto an inherently stable nickel oxide surface, thereby enhancing the SAM’s binding energy on the substrate. Also, they synthesised a new SAM molecule of their own, creating an innovative molecule that promotes more efficient charge extraction in perovskite devices. The primary outcome of the research is the potential transformation of the solar energy landscape. By improving the thermal stability of perovskite solar cells through the innovatively designed SAMs, the team has laid the foundation for these cells to perform efficiently even in high-temperature conditions.
“This breakthrough is pivotal as it addresses a major obstacle that previously impeded wider adoption of perovskite solar cells. Our findings could significantly broaden the utilisation of these cells, pushing their application boundaries to environments and climates where high temperatures were a deterrent,” said Professor Zhu.
The importance of these findings cannot be overstated. By bolstering the commercial viability of perovskite solar cells, CityU is not merely introducing a new player in the renewable energy market, it’s setting the stage for a potential game-changer that could play a vital role in the global shift towards sustainable and energy-efficient sources.
“This technology, once fully commercialised, could help decrease our dependence on fossil fuels and contribute substantially to combating the global climate crisis,” he added.
Power blackouts in Europe: Analyses, key insights, and recommendations from empirical evidence
by Andrej Stankovski, Blazhe Gjorgiev, Leon Locher, Giovanni Sansavini in Joule
Power grids — the web of electrical networks that sprawl across countries and continents — are under stress. Extreme weather events and volatile energy demands often push the system to the brink. Although these high-impact events can be very damaging, often overlooked is the impact of minor disruptions that trigger a domino effect throughout the system, according to a study analyzing European power blackouts. The findings showed that recovering power within 13 hours can reduce up to 52% of the power loss stemming from cascading events.
“Imagine dominoes when they are spaced far apart. Triggering it will not cause a chain reaction because it can’t reach the next tile. We want the power system to operate in this relaxed way,” says senior author Giovanni Sansavini of ETH Zurich, Switzerland. “Triggering events like wind, storms, or hacking will always happen. But we can understand how our system operates and adjust the distance of the tiles to mitigate the risk of cascading events.”
Drawing on decades-worth of data from 478 blackout events across Europe and 14,557 incidents across Italy, the research team had three goals: pinpointing the cause of power failures, identifying the early warning signs, and improving power system recovery.
They found that cascading events are the leading causes of blackouts across the European continent, responsible for 91% of lost power and 89% of recovery time. While weather events, often damaging power lines, are the most common initiators of cascading events, events stemming from volatile grid conditions are the most damaging. Human errors in operations, although rare, also have a very pronounced impact. The findings emphasize the importance of identifying early warning signs and operational training.
Teasing through the data from Italy, the researchers saw a pattern linked to blackouts. When the electrical demand reaches 80% of the power grid’s maximum capacity and when wind speeds reach 50 km/h (31.1 mph), the occurrence of power failures spikes. If these indications can be verified as early warning signs, operators may develop strategies to mitigate the risk of power system failure.
“Early warning signs are less-expensive ways to build resiliency in the system,” says Sansavini. “Because upon detection, you can activate some buffers in the system.”
When a power failure does happen, less-significant events tend to take longer to fix because of the prioritization of high-impact ones. This prolonged duration weakens the system, rendering it vulnerable to further threats that can exacerbate the damage. However, the researchers found that restoring the power within 13 hours can cut the system’s average exposure to cascades by 95% — avoiding up to 52% of cascading power loss. This suggests that 13 hours is the golden window for system operators to restore power.
Next, the researchers plan to construct a model based on their findings on cascading failures. This model will allow risk assessments of the power grid and scrutinize its vulnerabilities.
“We hope, via the model, we can simulate this chain reaction to understand how to stop it, like a hand in between the dominos tiles,” says Sansavini. “No system operator alone can win this battle; we need collaboration and system-wide assessments.”
The momentum of the solar energy transition
by Femke J. M. M. Nijsse, Jean-Francois Mercure, Nadia Ameli, Francesca Larosa, Sumit Kothari, Jamie Rickman, Pim Vercoulen, Hector Pollitt in Nature Communications
The world may have crossed a “tipping point” that will inevitably make solar power our main source of energy, new research suggests.
The study, based on a data-driven model of technology and economics, finds that solar PV (photovoltaics) is likely to become the dominant power source before 2050 — even without support from more ambitious climate policies. However, it warns four “barriers” could hamper this: creation of stable power grids, financing solar in developing economies, capacity of supply chains, and political resistance from regions that lose jobs.
The researchers say policies resolving these barriers may be more effective than price instruments such as carbon taxes in accelerating the clean energy transition.
“The recent progress of renewables means that fossil fuel-dominated projections are no longer realistic,” Dr Femke Nijsse, from Exeter’s Global Systems Institute. “In other words, we have avoided the ‘business as usual’ scenario for the power sector. “However, older projections often rely on models that see innovation as something happening outside of the economy.
“In reality, there is a virtuous cycle between technologies being deployed and companies learning to do so more cheaply. “When you include this cycle in projections, you can represent the rapid growth of solar in the past decade and into the future.
“Traditional models also tend to assume the ‘end of learning’ at some point in the near future — when in fact we are still seeing very rapid innovation in solar technology. “Using three models that track positive feedbacks, we project that solar PV will dominate the global energy mix by the middle of this century.”
However, the researchers warn that solar-dominated electricity systems could become “locked into configurations that are neither resilient nor sustainable, with a reliance on fossil fuel for dispatchable power.”
Instead of trying to bring about the solar transition in itself, governments should focus policies on overcoming the four key “barriers”:
- Grid resilience: Solar generation is variable (day/night, season, weather) so grids must be designed for this. Dr Nijsse said: “If you don’t put the processes in place to deal with that variability, you could end up having to compensate by burning fossil fuels.” She said methods of building resilience include investing in other renewables such as wind, transmission cables linking different regions, extensive electricity storage and policy to manage demand (such as incentives to charge electric cars at non-peak times). Government subsidies and funding for R&D are important in the early stages of creating a resilient grid, she added.
- Access to finance: Solar growth will inevitably depend on the availability of finance. At present, low-carbon finance is highly concentrated in high-income countries. Even international funding largely favours middle-income countries, leaving lower-income countries — particularly those in Africa — deficient in solar finance despite the enormous investment potential.
- Supply chains: A solar-dominated future is likely to be metal- and mineral-intensive. Future demand for “critical minerals” will increase. Electrification and batteries require large-scale raw materials such as lithium and copper. As countries accelerate their decarbonisation efforts, renewable technologies are projected to make up 40% of total mineral demand for copper and rare earth elements, between 60 and 70% for nickel and cobalt, and almost 90% for lithium by 2040.
- Political opposition: Resistance from declining industries may impact the transition. The pace of the transition depends not only on economic decisions by entrepreneurs, but also on how desirable policy makers consider it. A rapid solar transition may put at risk the livelihood of up to 13 million people worldwide working in fossil fuel industries and dependent industries. Regional economic and industrial development policies can resolve inequity and can mitigate risks posed by resistance from declining industries.
Commenting on the financial barrier, Dr Nadia Ameli from UCL’s Institute for Sustainable Resources, said: “There is a growing belief that, with the dramatic decline in the global average cost of renewables, it will be much easier for the developing world to decarbonise. “Our study reveals persistent hurdles, especially considering the challenges these nations face in accessing capital under equitable conditions.
A comparative analysis of integrating thermochemical oxygen pumping in water-splitting redox cycles for hydrogen production
by Aniket S. Patankar, Xiao-Yu Wu, Wonjae Choi, Harry L. Tuller, Ahmed F. Ghoniem on Solar Energy
MIT engineers aim to produce totally green, carbon-free hydrogen fuel with a new, train-like system of reactors that is driven solely by the sun.
In a study, the engineers lay out the conceptual design for a system that can efficiently produce “solar thermochemical hydrogen.” The system harnesses the sun’s heat to directly split water and generate hydrogen — a clean fuel that can power long-distance trucks, ships, and planes, while in the process emitting no greenhouse gas emissions.
Today, hydrogen is largely produced through processes that involve natural gas and other fossil fuels, making the otherwise green fuel more of a “grey” energy source when considered from the start of its production to its end use. In contrast, solar thermochemical hydrogen, or STCH, offers a totally emissions-free alternative, as it relies entirely on renewable solar energy to drive hydrogen production. But so far, existing STCH designs have limited efficiency: Only about 7 percent of incoming sunlight is used to make hydrogen. The results so far have been low-yield and high-cost.
In a big step toward realizing solar-made fuels, the MIT team estimates its new design could harness up to 40 percent of the sun’s heat to generate that much more hydrogen. The increase in efficiency could drive down the system’s overall cost, making STCH a potentially scalable, affordable option to help decarbonize the transportation industry.
“We’re thinking of hydrogen as the fuel of the future, and there’s a need to generate it cheaply and at scale,” says the study’s lead author, Ahmed Ghoniem, the Ronald C. Crane Professor of Mechanical Engineering at MIT. “We’re trying to achieve the Department of Energy’s goal, which is to make green hydrogen by 2030, at $1 per kilogram. To improve the economics, we have to improve the efficiency and make sure most of the solar energy we collect is used in the production of hydrogen.”
Ghoniem’s study co-authors are Aniket Patankar, first author and MIT postdoc; Harry Tuller, MIT professor of materials science and engineering; Xiao-Yu Wu of the University of Waterloo; and Wonjae Choi at Ewha Womans University in South Korea.
Similar to other proposed designs, the MIT system would be paired with an existing source of solar heat, such as a concentrated solar plant (CSP) — a circular array of hundreds of mirrors that collect and reflect sunlight to a central receiving tower. An STCH system then absorbs the receiver’s heat and directs it to split water and produce hydrogen. This process is very different from electrolysis, which uses electricity instead of heat to split water.
At the heart of a conceptual STCH system is a two-step thermochemical reaction. In the first step, water in the form of steam is exposed to a metal. This causes the metal to grab oxygen from steam, leaving hydrogen behind. This metal “oxidation” is similar to the rusting of iron in the presence of water, but it occurs much faster. Once hydrogen is separated, the oxidized (or rusted) metal is reheated in a vacuum, which acts to reverse the rusting process and regenerate the metal. With the oxygen removed, the metal can be cooled and exposed to steam again to produce more hydrogen. This process can be repeated hundreds of times.
The MIT system is designed to optimize this process. The system as a whole resembles a train of box-shaped reactors running on a circular track. In practice, this track would be set around a solar thermal source, such as a CSP tower. Each reactor in the train would house the metal that undergoes the redox, or reversible rusting, process.
Each reactor would first pass through a hot station, where it would be exposed to the sun’s heat at temperatures of up to 1,500 degrees Celsius. This extreme heat would effectively pull oxygen out of a reactor’s metal. That metal would then be in a “reduced” state — ready to grab oxygen from steam. For this to happen, the reactor would move to a cooler station at temperatures around 1,000 C, where it would be exposed to steam to produce hydrogen.
Other similar STCH concepts have run up against a common obstacle: what to do with the heat released by the reduced reactor as it is cooled. Without recovering and reusing this heat, the system’s efficiency is too low to be practical. A second challenge has to do with creating an energy-efficient vacuum where metal can de-rust. Some prototypes generate a vacuum using mechanical pumps, though the pumps are too energy-intensive and costly for large-scale hydrogen production.
To address these challenges, the MIT design incorporates several energy-saving workarounds. To recover most of the heat that would otherwise escape from the system, reactors on opposite sides of the circular track are allowed to exchange heat through thermal radiation; hot reactors get cooled while cool reactors get heated. This keeps the heat within the system. The researchers also added a second set of reactors that would circle around the first train, moving in the opposite direction. This outer train of reactors would operate at generally cooler temperatures and would be used to evacuate oxygen from the hotter inner train, without the need for energy-consuming mechanical pumps.
These outer reactors would carry a second type of metal that can also easily oxidize. As they circle around, the outer reactors would absorb oxygen from the inner reactors, effectively de-rusting the original metal, without having to use energy-intensive vacuum pumps. Both reactor trains would run continuously and would enerate separate streams of pure hydrogen and oxygen.
The researchers carried out detailed simulations of the conceptual design, and found that it would significantly boost the efficiency of solar thermochemical hydrogen production, from 7 percent, as previous designs have demonstrated, to 40 percent.
“We have to think of every bit of energy in the system, and how to use it, to minimize the cost,” Ghoniem says. “And with this design, we found that everything can be powered by heat coming from the sun. It is able to use 40 percent of the sun’s heat to produce hydrogen.”
In the next year, the team will be building a prototype of the system that they plan to test in concentrated solar power facilities at laboratories of the Department of Energy, which is currently funding the project.
“When fully implemented, this system would be housed in a little building in the middle of a solar field,” Patankar explains. “Inside the building, there could be one or more trains each having about 50 reactors. And we think this could be a modular system, where you can add reactors to a conveyor belt, to scale up hydrogen production.”
Life-cycle analysis of recycling of post-use plastic to plastic via pyrolysis
by Ulises R. Gracida-Alvarez, Pahola Thathiana Benavides, Uisung Lee, Michael Wang in Journal of Cleaner Production
Producing new plastic by advanced recycling of post-use plastic (PUP), instead of fossil-based production, can reduce greenhouse gas emissions (GHG) and increase the U.S. recycling rate, according to research by the U.S. Department of Energy’s (DOE) Argonne National Laboratory.
This is the first analysis of multiple U.S. facilities taking PUP all the way to new plastics again. Specifically, the new plastics are low-density and high-density polyethylene (LDPE and HDPE, respectively). The recycling process used is pyrolysis, whereby plastics are heated to high temperatures in an oxygen-free environment. The main product is pyrolysis oil, a liquid mix of various compounds that can be an ingredient in new plastic. The oil can replace fossil ingredients like naphtha and gases to manufacture ethylene and propylene. They are two important monomers, or building blocks, for plastic production.
The study collected 2017–2021 operating data from eight companies with varying pyrolysis oil production processes. The analysis shows an 18% to 23% decrease in GHG emissions when making plastic with just 5% pyrolysis oil from PUP compared to crude oil-derived LDPE and HDPE, respectively.
When factoring in current end-of-life practices for many plastics in the U.S., such as incineration, there is a further 40% to 50% reduction in GHG emissions when manufacturing pyrolysis-based LDPE and HDPE, respectively, according to the analysis. Reductions are much higher (up to 131%) in the European Union as more PUP is currently incinerated.
“As advanced recycling becomes increasingly efficient, it is poised to play a major role in achieving global sustainability goals by reducing waste and GHG emissions,” said Argonne Principal Energy Systems Analyst Pahola Thathiana Benavides, a study author. ?”It can transform hard-to-recycle plastics into a multitude of high-value raw materials, reducing the need for fossil resources and potentially minimizing the environmental impact of waste management.”
Advanced recycling enables reliance on PUP to produce valuable industrial chemicals and develop markets for recycled plastic materials. Pyrolysis is one of the most common advanced technologies being implemented at industrial scale to convert PUP that cannot typically be turned into new products using other means.
In addition to GHG emissions, the Argonne team assessed the fossil energy, water consumption and solid waste impacts of converting PUP into new plastics. The most-likely scenario of 5% recycled materials when compared to virgin production shows a reduction of 65% to 70% in fossil energy use, a 48% to 55% reduction in water use and a 116% to 118% reduction in solid waste.
Complete and selective recovery of lithium from EV lithium-ion batteries: Modeling and optimization using oxalic acid as a leaching agent
by Léa M.J. Rouquette, Martina Petranikova, Nathália Vieceli in Separation and Purification Technology
Researchers at Chalmers University of Technology, Sweden, are now presenting a new and efficient way to recycle metals from spent electric car batteries. The method allows recovery of 100 per cent of the aluminium and 98 per cent of the lithium in electric car batteries. At the same time, the loss of valuable raw materials such as nickel, cobalt and manganese is minimised. No expensive or harmful chemicals are required in the process because the researchers use oxalic acid — an organic acid that can be found in the plant kingdom.
“So far, no one has managed to find exactly the right conditions for separating this much lithium using oxalic acid, whilst also removing all the aluminium. Since all batteries contain aluminium, we need to be able to remove it without losing the other metals,” says Léa Rouquette, PhD student at the Department of Chemistry and Chemical Engineering at Chalmers.
In Chalmers’ battery recycling lab, Rouquette and research leader Martina Petranikova show how the new method works. The lab has spent car battery cells and, in the fume cupboard, their pulverised contents. This takes the form of a finely ground black powder dissolved in a transparent liquid — oxalic acid. Rouquette produces both the powder and the liquid in something reminiscent of a kitchen mixer. Although it looks as easy as brewing coffee, the exact procedure is a unique and recently published scientific breakthrough. By fine-tuning temperature, concentration and time, the researchers have come up with a remarkable new recipe for using oxalic acid — an environmentally friendly ingredient that can be found in plants such as rhubarb and spinach.
“We need alternatives to inorganic chemicals. One of the biggest bottlenecks in today’s processes is removing residual materials like aluminium. This is an innovative method that can offer the recycling industry new alternatives and help solve problems that hinder development,” says Martina Petranikova, Associate Professor at the Department of Chemistry and Chemical Engineering at Chalmers.
The aqueous-based recycling method is called hydrometallurgy. In traditional hydrometallurgy, all the metals in an EV battery cell are dissolved in an inorganic acid. Then, you remove the “impurities” such as aluminium and copper. Lastly, you can separately recover valuable metals such as cobalt, nickel, manganese and lithium. Even though the amount of residual aluminium and copper is small, it requires several purification steps and each step in this process can cause lithium loss. With the new method, the researchers reverse the order and recover the lithium and aluminium first. Thus, they can reduce the waste of valuable metals needed to make new batteries.
The latter part of the process, in which the black mixture is filtered, is also reminiscent of brewing coffee. While aluminium and lithium end up in the liquid, the other metals are left in the “solids.” The next step in the process is to separate aluminium and lithium.
“Since the metals have very different properties, we don’t think it’ll be hard to separate them. Our method is a promising new route for battery recycling — a route that definitely warrants further exploration,” says Rouquette. “As the method can be scaled up, we hope it can be used in industry in future years,” says Petranikova.
Metal Nanoclusters as a Superior Polysulfides Immobilizer toward Highly Stable Lithium–Sulfur Batteries
by Kai Sun, Yujun Fu, Taishu Sekine, Haruna Mabuchi, Sakiat Hossain, Qiang Zhang, Dequan Liu, Saikat Das, Deyan He, Yuichi Negishi in Small
The demand for efficient energy storage systems is ever increasing, especially due to the recent emergence of intermittent renewable energy and the adoption of electric vehicles. In this regard, lithium-sulfur batteries (LSBs), which can store three to five times more energy than traditional lithium-ion batteries, have emerged as a promising solution.
LSBs use lithium as the anode and sulfur as the cathode, but this combination poses challenges. One significant issue is the “shuttle effect,” in which intermediate lithium polysulfide (LiPS) species formed during cycling migrate between the anode and cathode, resulting in capacity fading, low life cycle, and poor rate performance. Other problems include the expansion of the sulfur cathode during lithium-ion absorption and the formation of insulating lithium-sulfur species and lithium dendrites during battery operation. While various strategies, such as cathode composites, electrolyte additives, and solid-state electrolytes, have been employed to address these challenges, they involve trade-offs and considerations that limit further development of LSBs.
Recently, atomically precise metal nanoclusters, aggregates of metal atoms ranging from 1–3 nanometers in size, have received considerable attention in materials research, including on LSBs, owing to their high designability as well as unique geometric and electronic structures. However, while many suitable applications for metal nanoclusters have been suggested, there are still no examples of their practical applications. Now, a team of researchers from Japan and China, led by Professor Yuichi Negishi of Tokyo University of Science (TUS), has harnessed the surface binding property and redox activity of platinum (Pt)-doped gold (Au) nanoclusters, Au24Pt(PET)18 (PET: phenylethanethiolate, SCH2CH2Ph), as a high-efficiency electrocatalyst in LSBs. The work is co-authored by Assistant Professor Saikat Das from TUS and Professor Deyan He and Junior Associate Professor Dequan Liu from Lanzhou University, China.
The researchers prepared composites of Au24Pt(PET)18 and graphene (G) nanosheets with a large specific surface area, high porosity, and conductive network, using them to develop a battery separator that accelerates the electrochemical kinetics in the LSB. “The LSBs assembled using the Au24Pt(PET)18G-based separator arrested the shuttling LiPSs, inhibited the formation of lithium dendrites, and improved sulfur utilization, demonstrating excellent capacity and cycling stability,” highlights Prof. Negishi. The battery showed a high reversible specific capacity of 1535.4 mA h g−1 for the first cycle at 0.2 A g−1 and an exceptional rate capability of 887 mA h g−1 at 5 A g−1. Additionally, the capacity retained after 1000 cycles at 5 A g−1 was 558.5 mA h g−1.
These results highlight the advantages of using metal nanoclusters in LSBs. They include improved energy density, longer cycle life, enhanced safety features, and a reduced environmental impact of LSBs, making them more environment-friendly and competitive with other energy storage technologies.
“LSBs with metal nanoclusters may find applications in electric vehicles, portable electronics, renewable energy storage, and other industries requiring advanced energy storage solutions. In addition, this study is expected to pave the way for all-solid-state LSBs with more novel functionalities,” highlights Prof. Negishi.
In the near future, the proposed technology can lead to cost-efficient and longer-lasting energy storage devices. This would help reduce carbon emissions and support renewable energy adoption, promoting sustainability.
High-temperature electrothermal remediation of multi-pollutants in soil
by Bing Deng, Robert A. Carter, Yi Cheng, Yuan Liu, Lucas Eddy, Kevin M. Wyss, Mine G. Ucak-Astarlioglu, Duy Xuan Luong, Xiaodong Gao, Khalil JeBailey, Carter Kittrell, Shichen Xu, Debadrita Jana, Mark Albert Torres, Janet Braam, James M. Tour in Nature Communications
Filtration systems are designed to capture multiple harmful substances from water or air simultaneously, but pollutants in soil can only be tackled individually or a few at a time — at least for now.
A method developed by Rice University scientists and collaborators at the United States Army Engineer Research and Development Center (ERDC) could help turn soil remediation processes from piecemeal to wholesale.
A team of Rice scientists led by chemist James Tour and researchers from the geotechnical structures and environmental engineering branches of the ERDC showed that mixing polluted soil with nontoxic, carbon-rich compounds that propel electrical current, such as biochar, then zapping the mix with short bursts of electricity flushes out both organic pollutants and heavy metals without using water or generating waste.
According to a study, the electrical pulses bring soil temperature up to 1000–3000 degrees Celsius as needed (1832–5432 Fahrenheit) in seconds, turning organic contaminants into nontoxic graphite minerals and toxic heavy metals into vapor collected via extraction pipes. Moreover, the process is beneficial to soil fertility, with experiments showing germination rates improve by 20–30% in remediated soil.
“Our high-temperature electrothermal process can remove multiple pollutants simultaneously,” said lead author Bing Deng, a postdoctoral research associate in the Tour lab. “This newly established method, which we called high-temperature electrothermal process (HET), is based on the flash Joule heating technique we developed a few years ago. It is the first time that direct electric heating has been used for soil remediation.”
Heavy metals like lead, arsenic, zinc, cobalt, copper, mercury and nickel and organic contaminants like pesticides and microplastics are the main pollutants in soil. In addition to anthropogenic activities, natural events like earthquakes and flooding can also drive soil contamination: Toxic ash released by wildfires like the ones that devastated Hawaii in August or any potential industrial waste released by thawing permafrost in the Arctic could contaminate vast areas of soil, calling for large-scale decontamination protocols.
However, current methods of removing pollutants from soil are time-consuming, costly and logistically challenging. Some decontamination techniques, such as surfactant leaching, also generate secondary waste streams and use up significant amounts of water and/or electricity. Finding better ways to decontaminate soil is critical for improved disaster readiness, making it a national security priority, Deng said.
“This method is ultrafast, which can be really useful in addressing emergency situations,” Deng added.
“Soil remediation technologies normally target only one or two heavy metals at a time, and often they’re not very successful or function at a much slower rate than electrothermal heating,” said Mine Ucak-Astarlioglu, an ERDC research chemist. “This method is very rapid, water-free and handles multiple pollutants in soil. Flash Joule heating is an incredibly promising technique in critical metals recovery from waste and heavy metals removal for remediation.”
Chris Griggs, an ERDC senior research physical scientist, said that, currently, polluted soil can either be dug up and hauled away from populated sites — an option he calls a “logistical nightmare” — or it can be treated on site to prevent toxic elements from migrating into the surrounding air, water or food supply.
“Certain contaminants might be fine — they’re not going to move. Other ones might migrate to groundwater and drinking water sources. Some could end up tainting crops, where you could have toxic heavy metals being drawn up through the roots of plants, etc.,” Griggs said. “Being able to regenerate the soil and put it right back where it was, that’s a huge advantage over existing technologies that are out there.”
A surprising effect of the rapid high-temperature treatment is that it leaves soil particle size and overall mineral composition relatively unchanged. In fact, the process improves the water infiltration rate and increases the pool of available nutrients, making the soil more fertile.
“It was surprising to us that we do not damage the soil in the process,” said Tour, Rice’s T.T. and W.F. Chao Professor of Chemistry and a professor of materials science and nanoengineering. “Plants actually like it more, because of the minerals that get freed up in the thermal cycling.”
Yi Cheng, a Rice postdoctoral researcher and lead co-author who helped with the characterization of soil properties, said the process works equally well on wet soil.
“Our process is economical and environmentally friendly,” Cheng added.
The study includes a lifecycle analysis that shows the process is scalable and promises to be more energy-efficient and cost-effective than traditional soil remediation practices like soil washing or thermal desorption.
“We developed two implementation models for both off- and on-site deployment, and we are looking forward to taking this process to the next stage — field testing,” Deng said.
The collaboration between Rice and ERDC could help the technology transition from the proof-of-concept stage to real-world practice.
“When it comes to the techno-economics and scalability of the process, we can lift a little bit heavier and go a little bit bigger than a university could, but the discovery side of research is where universities excel,” Griggs said. “It’s a good partnership.” “It’s a technical partnership, an educational partnership, and it also provides job opportunities,” Ucak-Astarlioglu said. “It’s a win-win situation for all university partners involved.”
Impacts of climate change, population growth, and power sector decarbonization on urban building energy use
by Chenghao Wang, Jiyun Song, Dachuan Shi, Janet L. Reyna, Henry Horsey, Sarah Feron, Yuyu Zhou, Zutao Ouyang, Ying Li, Robert B. Jackson in Nature Communications
A research study led by University of Oklahoma assistant professor Chenghao Wang tackled the critical issue of how city-scale building energy consumption in urban environments will evolve under the influence of climate change.
Fossil fuels account for approximately 40% of all building energy use in urban city centers in the United States, and the U.S. Energy Information Administration reports that residential and commercial buildings in U.S. cities are one of the major energy consumers (39%) and greenhouse gas emitters (28%).
“Understanding their future energy use is very important for developing climate change mitigation strategies, improving energy efficiency, developing and implementing energy and environmental regulations, policies, and incentive plans and enhancing the resilience and adaptation of our society under future climate and extreme weather conditions,” said Wang, who leads the Sustainable Urban Futures, or SURF, Lab in the OU School of Meteorology.
“Previous studies made strides in estimating how energy use might change at the national or state levels in response to future changes in climate,” he said. “However, there is a significant gap in our understanding when it comes to the city scale. As global cities commit to ambitious sustainability goals, a more granular understanding of energy use at the city scale becomes imperative.”
They examined 277 cities across the contiguous U.S., using model simulations and the most recent future climate projections from the Coupled Model Intercomparison Project, or CMIP6, dataset. They considered four possible warming scenarios that encompass a variety of possible climate warming scenarios and two electric power sector scenarios.
“In one power sector scenario, we assumed no future carbon policies would be implemented, but we also included a scenario that assumes rapid decarbonization and net-zero carbon emissions from the power sector by 2050, similar to with U.S. carbon-pollution-free goals announced by President Biden in 2023,” Wang said.
To investigate how urban building energy use would evolve under future climate change, Wang’s team used an indicator called energy use intensity, or EUI. The EUI is the energy used per square foot per year and is calculated by dividing the total energy consumed by the buildings by their total gross floor area.
“Due to climate change, we found that city-scale building EUI is projected to experience uneven changes by the 2050s when compared to the 2010s,” Wang said. “The largest increase in electricity EUI will mainly occur in the South, Southwest, West, and Southeast, which will see an increase of up to 7.2%.”
They discovered that the increase in electricity EUI during warm seasons and the hottest days will be much greater than the annual change, especially in the Northwest. This difference is mainly due to the higher air conditioning adoption rate and space cooling energy use under future warming. For each degree of warming, the average city-level space cooling EUI will increase by 13.8%.
“We found an average 10.1 to 37.7% increase in the frequency of urban summer peak building electricity EUI. However, some cities will experience over 110% increases. This will require higher grid capacity and also greater resilience against power outages during extreme heat waves,” Wang said.
The team also assessed the potential changes in the source energy used by urban buildings, considering energy losses during generation, transmission and distribution.
“Power sector decarbonization is very effective in curbing the source energy consumption of future buildings in cities, but it’s crucial to further reduce direct fossil fuel combustion in buildings,” Wang said. “Simply put, we need rapid electrification for future urban buildings.”
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