Pohang Light Source-II – Lightsources.org

Long-Life, Ultra-Fast Charging Zinc-Ion Battery with Stable Performance over 10,000 charge–discharge cycles

2025/06/172025/06/24

This study contributed to advancing Aqueous Zinc-Ion Battery (AZIB) technology by developing a novel vanadium (V)-based cathode material that offers both high specific capacity and long offers both high specific capacity and long cycle life.

Research Background and Goals

Lithium-ion batteries (LIBs) are widely used as key energy storage devices across various industries, ranging from consumer electronics to electric vehicles and grid-scale energy storage systems (ESS), due to their high energy density and excellent cycle life. However, lithium’s scarcity, high cost, and associated fire hazards have led to growing demand for next-generation alternatives.
Aqueous zinc-ion batteries, which use water-based electrolytes, are emerging as promising candidates due to their superior safety, cost-effectiveness, and high volumetric energy density. Nonetheless, they face critical limitations: structural degradation of the cathode material during repeated charge-discharge cycles results in rapid performance decline. In particular, vanadium pentoxide (V₂O₅), a commonly used cathode material, offers high theoretical capacity but suffers from poor structural stability and limited. It also undergoes dissolution and re-precipitation during cycling, degrading its electrochemical performance.
To address these challenges, this study proposes a new vanadium-based cathode material—Na₂V₆O₁₆・2H₂O (NaVO)—prepared by pre-intercalating sodium ions (Na⁺). This material stabilizes the structure and enhances the electrochemical performance of AZIBs.

Methods

The research focused on a structural stabilization strategy via Na⁺ pre-intercalation to improve the electrochemical performance of AZIBs. NaVO was synthesized through a sonochemical method, which expanded the interlayer spacing and allowed Na⁺ ions to function as structural pillars, thereby enhancing cycling stability.
The material’s physical and chemical characteristics were thoroughly analyzed, including real-time structural monitoring using synchrotron X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to evaluate charge transfer resistance and rate capability. Density functional theory (DFT) calculations confirmed that NaVO exhibits a significantly lower Zn²⁺ diffusion energy barrier compared to V₂O₅ , as well as reduced structural expansion—key advantages for long cycle life. Furthermore, Na⁺ ions were found to suppress dendrite formation on the Zn anode surface.

Results and Discussion

The study evaluated the effectiveness of cation pre-intercalation in improving the structural integrity and electrochemical performance of vanadium-based cathodes. Through a simple and efficient sonochemical synthesis method, Na⁺ ions were successfully intercalated into V₂O₅ to form NaVO, expanding the interlayer distance to approximately 4.3–8.4 Å.
This structural modification led to significant performance enhancements. A NaVO/Zn battery demonstrated a specific capacity of 126.3 mAh g^-1 at a high current density of 10 A g⁻¹ and retained 91.8% of its capacity even after 10,000 charge-discharge cycles. hese results represent 1.68- and 1.99-fold improvements over conventional V₂O₅ cathodes.
In-situ analyses revealed the mechanisms underlying the performance improvements. The flexible valence change of vanadium during Zn²⁺ insertion and extraction contributed to structural stability, while Na⁺ ions served as internal pillars to maintain structural integrity. The expanded interlayer spacing facilitated faster Zn²⁺ insertion, improving rate performance. DFT simulations further confirmed that Na⁺ pre-intercalation is crucial for enhancing structural stability and ion diffusion, thereby improving the overall electrochemical performance of vanadium-based cathodes.

Read more on PAL website

Explosive Prevention for 1,000km Next-Gen Battery!

2025/03/212025/03/25

A solution to the gas-filling problem of the next-generation long-distance battery¹⁾ has emerged.
A team led by Professor Lee Hyun-wook of UNIST’s Department of Energy and Chemical Engineering has identified the cause of Oxygen generation in olig Lithium of a new anode material for batteries and presented material design principles to solve this problem.

Overlithium materials can theoretically store 30% to 70% more energy in batteries than before through high-pressure charging of 4.5V or higher. In terms of electric vehicle mileage, you can go up to 1,000 kilometers on a single charge. However, this material has a problem of increasing the risk of explosion as Oxygen (O^-2) held inside the material is oxidized and released as gas (O₂) during the actual high-pressure charging process.

The research team analyzed that Oxygen is oxidized near 4.25V, causing partial structural deformation and releasing Oxygen gas. They proposed an electrode material design method that fundamentally prevents the oxidation of Oxygen. This strategy involves replacing some of the transition metals²⁾ of Lithium materials with transition metal elements with lower electronegativity.

The difference in electronegativity between the two metal elements causes the number of available electrons in the transition metal to increase, and Oxygen does not oxidize when electrons are concentrated around the highly electronegativity element. On the other hand, when the number of available electrons in the transition metal is insufficient, Oxygen gives electrons instead. It is oxidized to be discharged in the form of a gas.

The first author, Kim Min-ho (Currently a postdoctoral researcher at UCLA), explained “the difference between existing research that has focused on stabilizing Oxygen and preventing it from being discharged in the form of gas, whereas present research has focused on preventing the oxidizing process itself.”

In addition, this change in electron density increases the charging voltage through an Inductive Effect³⁾, thereby increasing the high energy density attainable. Since the energy density is proportional to the number of available electrons and the charging voltage, it is possible to store more energy per unit weight of the battery to replace the transition metal. This phenomenon is similar to the principle that if there’s more water in the dam and the drop is more significant, more energy is stored.

The researchers experimentally confirmed the transition metal substitution strategy’s inhibitory effect on Oxygen oxidation. Accelerator-based X-ray analysis showed that the generation of Oxygen gas was significantly reduced when a part of Ruthenium was replaced with Nickel. Furthermore, they theoretically demonstrated that charge rearrangement occurs through density functional calculation (DFT).

This study was conducted by Professor Seo Dong-hwa of KAIST, Chung-Ang University, Pohang Accelerator Laboratory, Professor Yu Zhang Li of UCLA, UC Berkeley, and Lawrence Berkeley Research Institute. The accelerator-based X-ray analysis was conducted by Professor Jang Hae-sung of Chung-Ang University (Co-first author), and the DFT theoretical calculation was led by Dr. Lee Eun-ryul (Co-first author) of the Lawrence Berkeley Institute in the United States.

Professor Lee Hyun-wook said, “We presented the direction of material development to cathode material researchers by librarying technology through various experiments and theoretical analysis,” adding, “It will help to develop long-distance driving battery materials without explosions with increased energy density.”

The study was carried out with the support of the National Research Foundation of Korea (NRF)’s international cooperation and development project on source technology. The results were published online on Feb. 19 in ‘Science Advances’, a sister paper of the world-renowned journal ‘Science’ published by the American Science Association (AAAS).

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Analyzing Metal Interface Reactions in All-Solid-State Batteries

2025/03/132025/03/20

This study developed a real-time X-ray photoelectron spectroscopy (XPS) analysis technique and utilized it to understand the lithium-ion behavior at metal interface layers in all-solid-state secondary batteries. Notably, the result of this research was published as a cover article in Advanced Energy Materials, one of the leading journals in the field, highlighting its significance.

Research Background and Goals
All-solid-state batteries (ASSBs) are gaining attention as next-generation batteries, offering higher energy density and enhanced safety than conventional liquid lithium-ion batteries (LIBs). In particular, lithium lanthanum zirconium oxide (LLZO)-based electrolytes are considered a key material for next-generation batteries because they exhibit excellent properties, including high ionic conductivity, chemical stability, and a wide bandgap. However, to ensure the long-term stability of batteries, it is necessary to understand their role at metal interfaces (Au, Ag) within the battery. Conventional XPS analyses have the strength of accurately measuring chemical property changes. However, they have limitations in analyzing under real conditions, as lithium compounds can be degraded due to their high reactivity in air during batteries’ charge-discharge. To solve this problem, the research team developed a real-time XPS analysis technique that can compare the reactions of Au and Ag metal interfaces with the previous analyses to elucidate the lithium-metal interaction mechanisms.

Methods
The research team performed real-time charge-discharge analysis using Ag and Au battery cells deposited onto the interface layers between LLZO solid electrolytes and current collectors. Then, Li-ion behavior was analyzed for high spatial resolution using operando XPS and scanning photoelectron microscopy (SPEM). This analysis was used to examine the spatial distribution of Li ions at a high resolution. These methods provided deeper insights into Li-ion migration mechanisms.

Results and Discussion
This study optimized a reliable real-time (operando) XPS analysis technique to determine the factors determining the ASSB performance. While conventional analysis methods are limited in making real-time observations of material changes at metal interfaces during the charge-discharge process, the newly developed real-time XPS technique enables analyzing the precise chemical and electronic structures of metal interface layers at each stage. The research team thoroughly examined the impact of metal interface layers, such as Ag, Au, and Cu, on the ASSB interfacial properties through this approach. As a result, it was confirmed that an increase or decrease in Li⁰ content serves as a critical metric for assessing the efficiency and reversibility of Li plating/stripping processes. Additionally, this research discovered that oxygen bonding within the metal interface layers reacts with Li⁺ ions to form Li₂O, which influences the chemical stability of interfaces. Furthermore, while comparative analysis of core-level electrons showed no significant changes, the formation of Li-metal alloys could be judged by changes in valence-band structure. Based on these analyses, this research identified the key factors that make Ag interface layers superior to other metal interface layers in terms of interface stability and ASSB performance.

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Development of Solid Electrolyte to Enhance Lithium Battery Performance

2025/02/052025/02/10

How convenient would it be if we could use smartphone batteries longer and more safely? A research team led by Professor Moon Jeong Park at POSTECH (Pohang University of Science and Technology) has announced an innovative research outcome that could turn this vision into reality, gaining significant attention from both academia and the public. In particular, this study builds upon their previous research published in Science last year, where they introduced the “plumber’s nightmare” structure to maximize lithium-ion battery performance, making it even more meaningful.

Lithium-ion batteries are broadly used in modern technologies, including smartphones. While the electrolyte is one of the core components of a battery, conventional liquid electrolytes have risks of leakage or explosion. Solid-state electrolytes are emerging as an alternative, but there have been limitations in balancing the electrolyte’s ‘mechanical strength’ and ‘ionic conductivity’.

A research team led by Professor Park Moon Jeong, Dr. Kim Ji-hoon, and doctoral student Lee Ho-joon from the Department of Chemistry at POSTECH has presented an innovative method that dramatically improves both the ionic conductivity and mechanical properties of batteries by adding only a tiny amount of lithium salt – less than one-tenth the level used in conventional electrolyte production that used more than a few mole concentration of lithium salt to increase ionic conductivity.

The key to this approach is that adding a very small amount of lithium salt to the PS-b-PEO¹⁾ block copolymer²⁾ selectively locates it at the terminal hydroxy groups (-OH) of the PEO chain. Through this, the research team succeeded in forming a sophisticated “plumber’s nightmare” structure unobserved in conventional polymer electrolyte systems.

The “plumber’s nightmare” structure refers to an arrangement where all polymer chain ends are entangled inward, just like plumbing pipes gather internally. This structure has six channels formed by the polymer chains, all connected. The structure provides a stable ion pathway as the lithium ions are locally present in the hydroxy groups at the center of the polymer channels. As a result, it creates an environment where ions can move quickly and efficiently while maintaining the hard and robust structure of the electrolyte.

The World’s Most Efficient PET-Degrading Enzyme

2025/01/092025/01/10

Polyethylene terephthalate (PET), which is used in drinking bottles, fibers, and many other applications, is one of a few plastics that can be broken down to its constituent monomers by naturally occurring enzymes. This study developed a landscape profiling method to identify and characterize the potential of microbial enzymes to degrade these plastics. Two enzymes were engineered with sequential mutagenesis and exhibited excellent performance relative to benchmarks, especially under the harsh conditions that are ideal for use in recycling applications..

Research Background and Objectives

PET (polyethylene terephthalate) is a representative general-purpose plastic widely used in various fields such as PET bottles, clothing, seat belts, takeout cups, and car mats. While most PET waste is separately collected and mechanically recycled into intermediate products, the recycled materials often degrade in quality, ultimately leading to incineration or landfill disposal. As a method to address this issue, chemical recycling technology has been developed to break down the PET polymer bonds using chemical catalysts and return them to the original raw materials. However, it has not been a perfect alternative due to the limitations of applying the method, which is caused by high temperature and high-pressure conditions. Therefore, the scientific community has turned to biological/biocatalytic recycling to solve these problems through enzymes. With complex bonding structures, enzymes react selectively with PET at low temperatures and in water solvent conditions to produce pure reactants. Thus, they are excellent at converting contaminated raw materials. There has been a fierce competition worldwide to develop PET-degrading enzymes using advanced technologies in various fields such as synthetic biology, computational chemistry, and AI-driven protein design.

Research Approach

The research team attempted to experimentally determine the fitness landscape of various enzyme protein sequences. Since conducting experiments on all sequences was physically impossible, it was necessary to use a statistical sampling method through a landscape. To construct a landscape of the Polyesterase-Lipase-Cutinase Family, a neighborhood analysis module was devised to control the network’s rigidity using distance histogram data for each protein sequence. This analysis generated a two-dimensional semantic network. Based on this semantic network, the research team proposed an innovative approach to experimentally measure the fitness for PET degradation activity and thermal stability using hierarchization and cluster sampling. Also, to improve the selected enzymes, the team attempted a unique strategy of applying cross-template engineering to reflect natural diversity and fitness information in a rational design based on the protein’s 3D structural information.

Results and Discussion

The new approach identified the most promising enzymes, Mipa-P and Kubu-P, among 158 nodes, which showed a superior PET-degradation rate and durability compared to other benchmarks. Cross-template engineering created heat-resistant variants MipaM19 (Mipa-PM19) and KubuM12 (Kubu-PM12) with melting temperatures exceeding 92 and 99°C, respectively. Surprisingly, Kubu-M12 withstood the condition of a minimum enzyme dosage of 0.58 g/mg and high PET loading of 20% and 30%, degrading more than 90% of the PET substrate within 8 hours. It showed overwhelming performance compared to other engineered benchmark enzymes. Moreover, Kubu-M12 withstood 99% ethylene glycol solvent and produced 30 mM level bis(2-hydroxyethyl) and terephthalic acid. For the first time in the world, the enzymatic catalytic glycolysis reaction was achieved at a significant level.

Technology Development for Producing Nearly Commercializable CO2-Free Green Hydrogen

2024/12/102024/12/11

This study proposes a photo-electrode material technology that may significantly change the development of photo-electrochemical hydrogen production technology. With this study, it is expected that hydrogen production using photo-electrodes at a commercial level will be possible soon.

Hydrogen is an eco-friendly energy source that reduces greenhouse gases and fine dust. It is essential for building a clean and safe society. Currently, hydrogen production relies on utilizing the by-product hydrogen from petrochemical processes and extracting from natural gas. However, these production methods generate CO₂, creating an ironic situation of contributing to global warming while aiming for a clean Earth.

The commercialization of solar-based production technology is urgently needed to address this issue. The U.S. Department of Energy (DOE) set specific goals for expanding clean hydrogen production in the “US National Clean Hydrogen Strategy and Roadmap” released in June 2023. Also, it established targets for commercializing solar-based hydrogen production technology at the level of a solar-to-hydrogen (STH) conversion efficiency of over 10 %, stability for over 1000 hours, and a PEC (photo-electrochemical) H₂ system cost of $ 2-4 per kilogram. Various research and investments are underway to achieve these goals.

Hydrogen (H₂) production requires photo-electrodes with high PEC activity and durability. However, surface defects, photo-corrosion instability, and especially instability at high potentials degrade PEC performance and stability. In this study, we introduced an HfO2 protective layer and a NiPt single-atom catalyst to improve the surface of a BiVO4 photoelectrode, classified as a low-cost material, and controlled strong corrosivity, achieving a high stability of over 800 hours. This was evaluated under one-sun solar light (100 mW/cm²). This study has significant implications as it is the first demonstration of long-term performance in the world. Furthermore, we achieved a solar-to-hydrogen conversion efficiency of 6.0 % of the self-driven photo-electrochemical water splitting device based on the BiVO4 photoelectrode, which is significant as it is approximately 90 % of the theoretical efficiency of the BiVO4 material.

Read more on PAL website

Improvement of Efficiency and Stability of Lead-Free Perovskite Solar Cells

2024/11/072024/11/12

Research Background and Objectives

Organic-inorganic halide perovskite solar cells have significant potential in solar energy development because of their long diffusion length, high light absorption coefficient, and excellent charge mobility. Due to these characteristics, the power conversion efficiency (PCE) of perovskite solar cells has rapidly increased from 3.8% to 26%. However, using lead (Pb) poses environmental and health risks, limiting commercialization. Therefore, active studies are being conducted on lead-free perovskite materials that maintain high efficiency while using less harmful substances.

Alternative materials such as tin (Sn), germanium (Ge), antimony (Sb), bismuth (Bi), and copper (Cu) have been proposed. Among them, tin is considered a promising candidate to replace lead due to its high charge mobility, low exciton binding energy, and suitable bandgap. However, tin-based perovskites suffer instability and low efficiency (below 15%) caused by oxidation and strong self-doping. This study aims to improve structural stability and PCE by introducing additives to overcome these limitations.

Experimental Methods and Procedures

In this study, we introduced various additives to improve the performance of tin-based perovskite solar cells, aiming to enhance grain growth and charge carrier mobility. The additives used in the experiment were bromides and various organic amine compounds, which were added to the precursor solution in small amounts. These additives were selected to help the vertical orientation of tin-based perovskite films and to increase grain size for charge recombination reduction and conductivity enhancement.

Solar cell thin films were fabricated through spin coating and annealing, and solvent evaporation and crystallization were processed without anti-solvent treatment. Subsequently, we analyzed electrical characteristics to evaluate the efficiency and stability of the films with additive introduction and conducted the X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses in parallel to determine the crystal structure and defect states.

Analysis Methods

To comprehensively analyze the effects of additives on tin-based perovskites, we applied synchrotron radiation analysis. In particular, small-angle X-ray scattering (SAXS) was used to investigate the effects of introducing additives on grain growth and structural orientation within the film. In addition, we observed the surface and cross-section of the film with an electron microscope to identify microstructural changes caused by introducing additives. Furthermore, to evaluate electrical characteristics, we measured open-circuit voltage (V_OC), short-circuit current density (J_SC), fill factor (FF), and PCE.

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Clays transport more water into the Earth’s interior than we thought

2024/06/012024/06/13

Nobody knows how much water is contained in the Earth’s interior. It’s 6400 kilometres from the surface to the centre, but the deepest point we can get to is mere 12 kilometres, so most estimations are based on assumptions and extrapolations about the composition of our planet’s mantle and core. A study by a research team led by Yongjae Lee from Yonsei University (South Korea), conducted at PETRA III as well as at Pohang (South Korea) and the Advanced Photons Source at Argonne National Laboratory (USA), now shows that minerals might carry more water into the Earth’s deep mantle than previously assumed.

Water affects many properties of Earth’s interior: heat, deformation, volcanic and seismic activity and more. These in turn have a direct influence on life on Earth. Knowing more precisely how water distribution across the Earth began and how it has changed over the Earth’s 4.6 billion-year history might give us clues as to how it will evolve in the future.

Experiments performed at DESY’s synchrotron facility PETRA III, PLS-II at Pohang, South Korea and the Advanced Photons Source at Argonne National Laboratory, USA demonstrated that sediment minerals from Earth’s continents called clays can significantly influence the water household of the Earth’s interior. This study was conducted as part of an effort to understand how the subduction process that sends tectonic plates down to the mantle affects the global transport and distribution of water through changes in the water content contained in minerals composing the subducting plate.

The team of scientists led by Yongjae Lee from Yonsei University (South Korea) used a heated diamond anvil cell, an experimental device that can expose material to extremely high pressures and temperatures, for experiments to simulate the path clay minerals would take in a cold subduction zone, where one tectonic plate disappears into the mantle underneath another tectonic plate. They then studied the breakdown of those clays in detail. The study published in Nature Communications concludes that clays in subducting sediments are responsible for delivering up to 22% of the total water transported into the lower mantle, which is a significant amount and helps constrain the question of how much water could be in the Earth’s deep interior in total.

When continental rocks weather and break down they eventually transform into clay minerals. “Clays are layered sheet silicates that are easily transported to the ocean via rivers and make up the top most part of the oceanic plate. When these sediments are transported via tectonic movement to the edges of the continents and dive down into the Earth’s interior via the subduction process, they are exposed to elevated pressures and temperatures,” explains Yoonah Bang, lead author and former student at Yonsei University. One of the major minerals contributing to the clays in the sediments is the alumina-carrying silicate mineral called pyrophyllite (Al₂Si₄O₁₀(OH)₂), “Using a pressure cell consisting of resistively heated diamond anvils, we are able to simulate pressures of up to some 230,000 atmospheres and temperatures of 900 degrees Celsius to mimic the subduction path pyrophyllite will take when it dives down to the lower mantle” says Bang.

In cold subduction zones like those located in the west Pacific, pyrophyllite transforms to the minerals gibbsite (Al(OH)₃) and diaspore (AlO(OH)) at a depth of some 135 kilometres. During this process, the minerals take up water from the surrounding hydrated slab and carry it down to a depth of 185 kilometres. From here sequential transformations take place to other water-bearing minerals that eventually drag the same amount of water initially contained in pyrophyllite to a depth of 700 kilometres in the lower mantle. “This shows how important it is to clearly understand the role of clay minerals during the subduction process,” explains Y. Lee, who led this work. “Our research implies that clay minerals such as pyrophyllite would have transported about 2~3% of global ocean water down to the lower mantle over 2.5 billion years.”

“The findings contribute to the overall understanding of the hydration of the Earth through its history”, says Hanns-Peter Liermann, leader of the ‘Extreme Conditions Beamline’ P02.2 at PETRA III, where part of the research was performed.

Read more on DESY website

Image: An illustration depicting that water contained in clay minerals is transported to the lower mantle through breakdown reactions along the subducting plate

Credit: Authors/Original Publication

New technology on the beamlines gifts sleep back to staff and users

2022/01/172022/01/17

Dohyun Moon, Beamline Senior Scientist at Pohang Light Source II in Korea, and Michele Manfredda, Scientist in the Photon Transport Group at FERMI in Italy, talk about new technology that is delivering remote control, automation and robot systems. All of these advances reduce the need for humans to be on the beamlines round the clock.

As Michele says, “The best science that we can do at a light source is the one that we do when we sleep and the machines and computers work.”

#LightSourceSelfies: Dedication to single crystals

2021/11/182021/11/18

Dohyun Moon is a Beamline Senior Scientist at the Pohang Light Source II in South Korea. His main work is supporting users visiting the facility for supramolecular crystallography experiments. Dohyan’s research involves characterising the structure of single crystals using crystallography. He is constantly researching the inside of unknown materials and getting good singe crystals challenges and motivates him every day. Hear him talk about his light source journey, aspirations for the future and advice for those considering entering into the realm of light sources.