A new study from Khalifa University demonstrates how covalent organic frameworks can significantly improve the stability and efficiency of lithium-sulfur batteries��

Unpack the science behind Li-S innovation – Listen Now!

Lithium-sulfur (Li-S) batteries are often considered the next big leap in energy storage due to their higher energy density and lower cost compared to traditional lithium-ion batteries. However, their widespread use has been limited by one major problem: the polysulfide shuttle effect – a phenomenon where lithium polysulfides (LiPSs) dissolve and migrate within the battery, leading to capacity loss, poor efficiency, and short cycle life.����

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A team of researchers from Khalifa University, including Dr. Dinesh Shetty, Dr. Kayaramkodath Chandran Ranjeesh and Safa Gaber, has collaborated with researchers from CSIR-National Chemical Laboratory, India, and Technische Universitat Dresden, Germany, to develop a solution. The research team developed a novel sulfur-hosting material based on covalent organic frameworks (COFs). These materials offer strong chemical and physical confinement of LiPSs, preventing their migration and stabilizing battery performance over hundreds of cycles.����

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The team published their work in .����

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“The rapid evolution of modern electronics and electric vehicles has motivated the development of safer rechargeable batteries with greater capacity and lower costs,” Dr. Shetty said. “Rechargeable lithium-sulfur batteries are a promising candidate but despite extensive research, their performance remains significantly below theoretical potential. We used molecular-level material design to unravel the structure and property relationship in enhancing the performance of sulfur-hosting cathodes for Li-S batteries.”��

“The rapid evolution of modern electronics and electric vehicles has motivated the development of safer rechargeable batteries with greater capacity and lower costs. Molecularly engineered covalent organic frameworks can unlock the true potential of lithium-sulfur batteries for next-generation energy storage.”

Dr. Dinesh Shetty, Associate Professor, Khalifa University.

 

Covalent organic frameworks are a class of materials that form two- or three-dimensional structures through reactions between their organic components, resulting in strong, covalent bonds that create porous, crystalline materials. The research team designed chalcone-linked nanographene COFs that serve as advanced sulfur hosts. These COFs provide dual confinement for LiPSs through physical trapping, as the microporous structure prevents them from escaping, and chemical anchoring. The chalcone and pyridine groups in the COFs form strong bonds with the lithium polysulfides, keeping them in place. These molecular interactions suppress the shuttle effect and allow for more efficient and stable sulfur utilization.����

 

In the team’s experiments, the batteries retained 80 percent of their original capacity, even after 500 cycles, while enhanced redox kinetics improved charge and discharge rates. With further optimization, this technology could soon power anything from electric vehicles to grid-scale renewable energy storage, bringing us closer to a cleaner, more sustainable future.����

 

Jade Sterling
Science Writer

The post Next-Gen Materials to Overcome Lithium-Sulfur Battery Challenges�� appeared first on Khalifa University.

A team of researchers from Khalifa University has developed a techno-economic model to evaluate and compare energy-storage systems (ESS) in green building design.��

Dr. Ahmad Mayyas, Assistant Professor, Assia Chadly, MSc student, Dr. Elie Azar, Associate Professor, and Dr. Maher Maalouf, Associate Professor, all from the Khalifa University Department of Industrial and Systems Engineering, published their results in the journal and also recently had their work feature as a story in pv magazine, which is a monthly trade publication widely read by the international photovoltaics (PV) community.

They compared lithium-ion batteries, proton-exchange membranes reversible fuel cells (PEM RFC), and reversible solid oxide cells (RSOC), with all three types of storage systems connected to a stand-alone photovoltaic system. Their model was tested on what would be a typical commercial building located in Los Angeles to determine the most efficient energy-storage system of the three.

“Low-energy buildings can be designed to be self-sufficient if connected to a suitably sized renewable-energy system, supported by energy-efficiency measures that minimize their energy demand,” Dr. Mayyas said. “Since energy generation is often intermittent and weather-dependent, we need to consider and plan for situations where energy is not available.”

The electric grid must always be balanced so that electricity generation exactly equals electricity usage. Though we often think of intermittent renewable energy resources, such as solar and wind, as susceptible to not being able to provide enough energy, there are invariably times when there is more electricity generated than we can use. Excess electricity in the system leads to curtailment, where output is intentionally reduced, limiting the value of impacted renewable energy systems.

“The main role of the ESS is to store energy when supply exceeds demand and release it when the situation is reversed,” Dr. Mayyas said.

There are a wide range of specifications and classifications for ESS, depending on their storage mechanism and potential applications, with key differences found in their structure and mode of operation. Some systems use supercapacitors, some use lithium-ion batteries. Others use fuel cells or flywheels, but all have lifetimes measured by the total number of cycles the system can offer.

“Batteries and hydrogen-based ESS offer high power ratings, energy density, and storage duration, all of which make them suitable for medium- and long-term storage needs,” Dr. Mayyas said. “But system aging lowers their performance and typically increases the energy-storage cost. Plus, they age at varying rates: hydrogen systems suffer from higher levels of degradation at the cell and stack levels, for example.”

The team’s model considered a medium office building, defined as a three-floor office building, located in Los Angeles. Its assumed electricity demand ranged from 18.69kW during the night to 178.30kW during the day in August. The team chose a rooftop solar array with a capacity of 400kW and 19 percent efficiency.

Their model looked at the levelized cost of storage (LCOS), considering the economic burden of the three energy-storage systems. They found that upfront capital in installing the technologies accounts for more than 65 percent of the total LCOS, making it the most important component in the model. Bringing the capital cost down would have the most impact on reducing the overall cost of such systems.

Additionally, as each system had a different rate of aging and therefore a different operating lifetime, the LCOS depended on the lifetime of each system.

“The LCOS is sensitive to changes in capital costs and lifetime among many other things,” Dr. Mayyas said. “Of the three storage systems, lithium-ion batteries were the most sensitive, but they also offered the lowest LCOS. All three systems are economically appealing, however.”

However, the fuel cells in the two other systems, although expensive, help improve the reliability and resiliency of the commercial building when supplied with renewable-energy.

“Further work could include other energy-storage systems and hybrid models looking at lower capital costs and higher efficiencies,” Dr. Mayyas said. “Also, expanding the analysis to a comparison between different locations would help understand how the LCOS changes with different climates.”��

Jade Sterling
Science Writer
19 July 2022

The post Comparing the Cost of Energy-Storage Systems for Renewable Energy appeared first on Khalifa University.

Lithium batteries are reaching technological maturity and metal-organic framework-based materials may be a long-term answer.��

Lithium-ion batteries (Li-ion) are everywhere. For the decades since their inception, they have been powering billions of devices including mobile phones, cameras, laptops, e-scooters and electric vehicles. This is due to their higher energy density and lithium being the lightest of all metals with great electrochemical potential. However, as demand for batteries grows, supply of lithium is struggling to keep up. Finding alternatives is becoming increasingly important.

Dr. Shashikant Patole, Assistant Professor of Physics at Khalifa University, has published a review paper investigating the potential of metal-organic framework (MOF)-based materials in batteries. With Dr. Anukul Thakur, Korea Institute of Materials Science, Dr. Mandira Majumder, College de France, Dr. Karim Zaghib, McGill University, and Dr. M. V. Reddy, National University of Singapore, the review paper was published in ��

“The compact structure of Li-ion batteries has contributed hugely towards revolutionizing electronic gadgets by adding features such as compactness, efficiency, flexibility, and mobility,” explained Dr. Patole. “Nevertheless, after four decades of intense research and advancement, Li-ion battery technology is reaching its stalling point, but the demand for higher energy density prevails.”

Some researchers are investigating ways to optimize current Li-ion systems by changing the cathode, anode and electrolyte materials, but the continued use of lithium in these types of batteries is becoming a major cause of concern due to the limited availability of lithium on earth. Additionally, lithium is commonly sourced from brine in an energy and water intensive process.

“The rapid expansion of Li-based batteries in various applications has made the cost of the raw materials increase steeply in recent years,” said Dr. Patole. “Employing systems with other charge storage mechanisms could be the answer.”

In their review paper, Dr. Patole’s team ��ݮ��Ƶ the current challenges being faced by the development of metal organic framework (MOF)-based battery technologies, and possible ways to overcome these issues.

MOFs are known for their extraordinarily high surface areas with pores that are tunable and internal surface properties that can be adjusted to requirements. They can be made with abundantly available low-cost materials, such as sodium, potassium, magnesium and aluminium, for use in MOFs in batteries.

Metal ions are combined with organic linkers to provide endless possibilities of pore shape and size and physical properties of the resultant MOF. By altering the combination of ingredients, properties such as porosity, particle morphology, stability and conductivity can be tailored for specific applications, and this tunable conductivity is of particular interest to the research team.

MOFs have been shown to be useful not only as electrode materials but also as catalysts in metal-air batteries and sulfur hosts in metal-sulfide batteries.

“The pore features and pore size distribution are important attributes of any electrode material and play a vital role in imparting the desired properties to the MOF,” explained Dr. Patole. “MOFs or MOF-derived materials can act as both the anode and cathode in rechargeable batteries. Due to their large surface area, they can store charge effectively and are very promising materials in many types of batteries. For example, sodium-ion batteries are striking alternatives to lithium-ion batteries due to the cost-effectiveness and abundance of sodium.”

The team points out that advanced nanostructures such as MOFs can offer significant structural strength in harsh conditions, easy accessibility of reactants to the active sites, and effective electron transport pathways. Carefully designing MOFs is crucial to extend the adaptability of these materials for energy storage systems.

In spite of the significant progress made so far on MOF-based materials for battery systems, several challenges remain.

Designing the perfect MOF structure is no easy task, and transforming an MOF into an MOF-based material introduces further structural and architectural difficulties. Additionally, pure MOFs suffer from instability, which needs to be overcome for use in practical energy storage devices.

Although there are many challenges still to face, researchers are developing more advanced characterization techniques and a fundamental, in-depth understanding of the structure-performance relationship of MOF-based materials, and they expect to achieve the perfect MOF for practical energy storage devices in the near future.

Jade Sterling
Science Writer
15 August 2021

The post Khalifa University Researcher Investigates the Potential for Next-Generation Batteries appeared first on Khalifa University.

Research into advanced materials at Khalifa University is unlocking a number of new technologies that can be used to generate and store renewable energy more efficiently.

Dr. Nirpendra Singh, Assistant Professor of Physics at Khalifa University, and colleagues recently published three papers that investigate the development of materials with a number of applications for renewable energy.

These papers explore new materials that could help improve the performance of thermoelectric materials capable of converting heat into electricity more efficiently, and sulphur-based batteries with high energy densities that could replace traditional lithium-ion batteries.

Understanding Phonon Dynamics of Copper Pseudohalides

A team consisting of to determine how effective they are in conducting the heat. Their study was published in the journal .��

Phonon transport of materials plays a significant role in determining their thermoelectric performance. Dr. Singh’s team investigated two copper-based compounds – copper thiocyanate (CuSCN) and copper selenocyanate (CuSeCN) – which are candidates for inexpensive large-area photovoltaic use, but until now, have not been deeply studied for phonon transport. The research team comprehensively determines phonon thermal transport with the most sophisticated computational approach available to date. The electron localization function profile is used to explain phonon softening, which was found to be the leading cause of low in-plane lattice thermal conductivity. The high phonon scattering rates in CuSeCN give rise to lower lattice thermal conductivity than CuSCN, suggesting its better thermoelectric performance, Dr. Singh explained.��

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Lead-free Double Perovskite Cs2PtI6: A Promising Thermoelectric Material

While transparent materials are vital for renewable energy harvesting, thermoelectric materials are crucial for turning heat – either heat from the sun or waste heat from power plants and cars – into renewable energy. One promising thermoelectric material is double perovskite Cs2Ptl6, a lead-free hybrid material containing cesium and platinum.��

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Dr. Singh, Dr. Muhammad Sajjad, and Dr. J. Andreas Larsson from the Luleå University of Technology, Sweden, in work recently published in the journal .

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The researchers found that the Cs2Ptl6 shows high thermoelectric performance at and above room temperature and is therefore worth exploring for thermoelectric applications. Cs2PtI6 has a lattice thermal conductivity that is 8-fold smaller than that of the commercial thermoelectric material Bi2Te3. Nanostructuring and alloying of Cs2Ptl6 can lead to further improvement in thermoelectric performance, possibly making it useful for conventional thermoelectric generators.�� For future energy needs, finding alternative and better thermoelectric materials is critically needed, Dr. Singh said.��

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Polar C2N Sheet: A Potential Electrode Enhancer in Sodium–Sulfur Batteries

With clean renewable energy production comes the need for energy storage since renewable energy supply is intermittent. Currently, metal-ion batteries are used, but low energy density and relatively high cost limit their viability for large-scale usage.

Alkali metal-sulfur batteries have emerged as a promising option, especially in applications requiring high energy storage capacity. However, one issue with metal-sulfur batteries is the so-called ‘shuttle effect.’ In the shuttle effect, metal particles called polysulphides dissolve into the battery’s electrolyte and are transported from the sulfur cathode to the metal anode. This results in a reduction in capacity and charging performance of the battery.

Finding a way to suppress the shuttle effect is crucial to metal-sulfur battery performance and lifetime.. They published their findings in the journal.

The 2D materials the team investigated were nitrogenated holey graphene (C2N) and nonpolar polyaniline (C3N). Both C2N and C3N are 2D nanostructures, which can help to anchor the metal polysulphides to the sulfur cathode and improve the electric conduction of the sulphur cathode in metal-sulfur batteries.

The researchers found that C2N was a stronger anchor than C3N, paving the way for a cost-effective C2N nanosheet as an anchoring material for the high-energy and high-capacity batteries needed for large-scale photovoltaic energy storage.

As energy consumption continues to rise, finding new materials that can make renewable solar energy generation and storage cleaner and more efficient will be key to meeting the world’s growing energy demands sustainably.

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Jade Sterling
Science Writer
12 April 2021

The post Getting More Clean Energy with New Materials appeared first on Khalifa University.

10-meter Diameter Prototype to Help in Energy Storage, High-Efficient Power Generation, Desalination and Other Applications

Khalifa University and Wahaj Solar (Wahaj Investment L.L.C) have signed an agreement to test and verify a patented prototype in the Concentrated Solar Power (CSP) industry at the Masdar Institute Solar Platform (MISP).

The 10-meter diameter high-flux solar furnace – the first medium-scale point solar concentrator –can focus solar energy efficiently to a lower point fixed on the ground generating a very high temperature which is easily accessible. This system is unique since the focal point is fixed on the ground while the solar disk turns around it throughout the day. This would result in many applications including low cost solar energy storage allowing for 24/7 electricity production, high efficiency in electricity production, hydrogen generation from water, desalination, as well as melting metals or sand to produce glass.

The project period is one year during which the performance of the concentrator will be tested analyzed, and certain applications demonstrated by a team led by Dr. Nicolas Calvet, Assistant Professor, College of Engineering, and Chair of the Masdar Institute Solar Platform – Khalifa University. The invention has already received favorable reviews from experts in reputable international research institutes worldwide.

Dr Arif Sultan Al Hammadi, Executive Vice-President, Khalifa University of Science and Technology, said: “The MISP is a unique world-class research facility, pushing the boundaries by being multipurpose, modular and the first-of-its-kind, bringing niche capabilities to the UAE. We welcome collaborations with industry partners that will result in cutting-edge solutions in solar power, thereby facilitating faster adoption of sustainable energy technologies. We believe testing of this innovative prototype from Wahaj Solar will further demonstrate MISP’s capabilities and help in the development of CSP components, and high-temperature thermal energy storage (TES) solutions.”

Motasim Al Daour, the majority shareholder at Wahaj Solar said: “We are working with the Masdar Institute Solar Platform at Khalifa University because we would like to take advantage of the available expertise and resources at this world class facility. In collaboration with Khalifa University, we are keen launch this potentially breakthrough invention from the UAE to the entire world in the hope of considerably contributing to the progress of the CSP technology as an alternative clean source of energy.”

The technology is already patented by Wahaj’s Dr Ayman Al-Maaitah in the US, European Union, GCC and at the World Intellectual Property Organization (WIPO) with priority protection in 150 countries worldwide.

The MISP is a unique tool for developing large scale TES systems for on-demand and ‘dispatchable’ electricity production. Initially built as a demonstration plant in 2009, the facility has been significantly modified and extended by Masdar Institute in 2014 to become a user research facility also valued by industry, capable of testing large scale TES units up to 500 kWh storage capacity. This innovative and educative research facility has already attracted several international collaborations.

Clarence Michael

News Writer

20 January 2019

The post KU and Wahaj Solar Sign Agreement to Test Innovative Prototype at Masdar Institute Solar Platform appeared first on Khalifa University.

Over the past decade, the UAE has demonstrated a serious commitment to the development of renewable and alternative energy, which is one of the pillars of the country’s economic diversification strategy. The empowerment of renewable energy technology and the rapid advancements in energy storage technologies will lead to significant improvements in our daily life. Batteries play a key role as an energy storage device to overcome the operational challenges caused by the intermittent nature of renewable energy, while advanced flexible energy storage solutions will allow for further miniaturization of portable electronic devices, including wearables.

A major limitation to better electrochemical energy storage systems lies in the electrode. Electrodes are the places in every storage device i.e., battery or supercapacitor, where the chemical reactions occur and where the ions, or charged particles, are stored. Researchers around the world have been racing to develop high-performance electrode materials.

Considering the above mentioned research demands, a collaborative team of researchers at Khalifa University have developed excellent electrodes using ultrathin 2D materials and their 3D nano-architectures, for safer, more powerful and less expensive batteries and for flexible supercapacitor applications. The research is described in two papers published recently in the journals and

The research is being led by Dr. Shoaib Anwer, a postdoctoral fellow working with Prof. Kin Liao in the Department of Aerospace Engineering, Professor Lianxi Zheng of Mechanical Engineering, Prof. Wesley Cantwell, Director of the Aerospace Research and Innovation Center (ARIC), and Dr. Shashikant Patole of the Department of Physics.

The Nature-Inspired Anode Material for Sodium-Ion Batteries

All batteries produce current in the same way – through an electrochemical reaction involving electrodes (an anode and a cathode) and electrolyte. In a rechargeable battery, the reaction is reversible. When electrical energy from an outside source is applied to a rechargeable battery, the negative-to-positive electron flow that occurs during discharge is reversed, and the cell’s charge is restored.

The most common and widely used rechargeable batteries are lithium-ion, where lithium is the charge carrier, moving from the negative electrode to the positive cathode. But since 2011, there has been a revival of research interest in sodium-ion batteries because of growing concerns about the availability of lithium and the increasing cost. In 2015, prices for lithium almost tripled to more than USD 20,000 a ton in just ten months.

“Sodium-ion batteries are an efficient, low-cost and sustainable alternative to the expensive lithium-ion batteries used today in most large-scale energy storage applications in renewable energy and smart grids owing to the abundance of sodium in nature compared to lithium,” said Dr. Anwer. “However, the practical applications of SIBs have been constrained­— sodium ions are nearly 25 percent larger than lithium ions, and the larger sodium ions do not fit into the crystal structure of the electrodes, where the chemical reactions take place.”

Ideally, the anode and cathode materials should be able to withstand repeated cycles of sodium storage without degradation. However, the typical anode material used in commercial lithium-ion batteries, graphite, cannot be used in SIBs as it cannot store the larger sodium ion in large quantities. The KU researchers investigated 2D nanostructured materials, such as transition-metal sulfides and hydroxides, and carbon-rich materials as possible electrode materials to overcome the limitations posed by graphite anodes and to improve the properties of rechargeable SIBs.

Molybdenum disulfide (MoS₂) has been identified as a particularly attractive anode material for SIBs due to its layered structure. 2D materials, sometimes referred to as single layer materials, are crystalline materials comprising a single layer of atoms. Molybdenum disulfide monolayers comprise a unit of one layer of molybdenum atoms covalently bonded to two layers of sulfur atoms, forming a nanosheet.

“The large interlaying spacing and weak van der waal interaction among the molybdenum disulfide layers are beneficial for reversible sodium ion intercalation and extraction,” Dr. Anwer explained. “But poor electronic conductivity and slow sodium diffusion kinetics makes MoS₂ as an anode material for SIBs limited.”

To overcome these key problems, and to improve molybdenum disulfide’s performance, Dr. Anwer scaled down the structure of MoS₂ to ultra-thin nanosheets, and a two-dimensional crystalline form with a thickness of few atomic layers was achieved. Then they controlled the closely interconnected ultrathin molybdenum disulfide nanosheets synthesis to form a 3D marigold flower-like microstructure. Finally, they wrapped these microstructures in atomically thin sheets of graphene, forming MoS₂-Graphene networks.

“Inspired by the marigold flower structures in nature, we developed a simple hydrothermal approach to synthesize the flowery 3D MoS₂ ultrathin structures, followed by graphene wrapping to obtain the MoS₂-G interconnected 3D conductive network,” said Dr. Anwer. “Such a unique MoS₂-G 3D architecture influenced by the surface-to-surface intimate contact between MoS₂ and graphene effectively improves the electron/ion transport kinetics of MoS₂ and ensures structural integrity, resulting in superior electrochemical performance.”

“The prepared electrode exhibited an outstanding specific capacity, remarkable rate performance, and long cycle life, while our proposed synthesis strategy and 3D design offer a unique way to fabricate high-performing anode materials for low-cost and large-scale applications in SIBs,” elaborated Dr. Anwer.

The high energy density SIBs would be well suited for those applications currently dominated by lithium-ion batteries, including long-range electric vehicles and power-hungry consumer electronics, reducing energy storage costs across the board.

A Flexible Electrode for Supercapacitor Application

Dr. Anwer and his co-workers also leveraged advancements in nanotechnology and 2D materials to develop flexible electrode materials for supercapacitors application. Supercapacitors have emerged as the advanced energy storage system for portable and wearable electronics due to their excellent power density, charging time and cycling life.

The researchers prepared a freestanding flexible supercapacitor electrode, based on Ni(OH)₂ nanosheets (NSs) grown on a carbon nanotube foam (CNTF) as core–shell 3D Nano-architectures.

“The new flexible electrode displayed outstanding electrochemical performance by retaining its shape and structure under bending or compression without any fracture,” Dr. Anwer said. “The highly conductive CNT foam, which comprised a 3D network of CNTs – which are tiny cylindrical tubes made of tightly bonded carbon atoms, measuring just one atom thick walls – and the unique nanostructure design of the nickel hydroxide nanosheets, facilitated rapid ion transport near the electrode surfaces, and improved charge storage activity.”

The proposed synthesis strategies developed by Dr. Anwer and his team, which leverage 2D materials with a 3D design, reveal a unique way to fabricate promising electrode materials for energy storage devices.

Jade Sterling, News and Features Writer, and Erica Solomon, Senior Editor
13 October 2019

The post Wonders of 2D Materials & their 3D Nano-Architectures for Energy Storage appeared first on Khalifa University.