The IOP Journal “Materials Futures” has included our paper led by alumnus Qingsong Wang in the collection of the “Materials Futures 2023 Best Paper Award”.

J. Wang, S.L. Dreyer, K. Wang, Z. Ding, T. Diemant, G. Karkera, Y. Ma, A. Sarkar, B. Zhou, M.V. Gorbunov, A. Omar, D. Mikhailova, V. Presser, M. Fichtner, H. Hahn, T. Brezesinski, B. Breitung, Q. Wang, P2-type layered high-entropy oxides as sodium-ion cathode materials, Materials Futures 1(3) (2022) 035104.

New paper in Carbon on hydrogen densification in carbon nanopore confinement: Insights from small-angle neutron scattering using a hierarchical contrast model from our long-term collaboration with Oskar Paris (Montanuniversität Leoben).

New paper published in Langmuir on emerging frontiers in multichannel membrane capacitive deionization. Spearheaded by our group alumni Choonsoo Kim, together with Hyunjin Kim, Seonghwan Kim, and Byeongho Lee from Kongju National University, our joint work dives deep into the advancements and future prospects of MC-MCDI technology. We explore how this innovative approach not only pushes the boundaries of efficiency and sustainability in addressing global water scarcity but also sets new benchmarks for electrochemical desalination.

New battery published in ACS Applied Materials & Interfaces on hybridization of carbon spherogels with titanium oxide and sulfur enables high performance lithium-ion battery electrodes. As a result from our research project with Michael Elsaesser from the Paris Lodron Universität Salzburg, we introduce a novel approach to enhancing lithium-ion battery electrodes. We have successfully combined titanium oxide and sulfur with carbon spherogels, achieving high performance in terms of stability and capacity. Our method resulted in electrodes combining high charge storage capacity and electrical conductivity, while maintaining a core-shell morphology. The process involved producing carbon spheres encapsulating titania and sulfur using a template-assisted sol-gel route, followed by thermal treatment with hydrogen sulfide gas. This treatment fully preserved the microporous hollow sphere architecture of the carbon shells, facilitating sulfur deposition and titania crystal protection.

New review paper published in Desalination. Our manuscript examines various Direct Lithium Extraction (DLE) technologies, a response to increasing lithium demand driven by its extensive use in batteries for diverse applications. Traditional lithium extraction methods, including mining and evaporation ponds, pose significant environmental challenges and may not suffice to meet global demand. DLE offers a potentially more efficient and sustainable alternative, akin to the impact of shale extraction on the oil industry. This study provides a comprehensive analysis of DLE techniques such as adsorption, ion exchange, membranes, direct carbonation, and electrochemical processes. It assesses their operational fundamentals, advantages, and limitations. The research aims to evaluate DLE’s capacity for efficient and sustainable lithium recovery amidst rising energy sector demands, addressing associated challenges like cost, environmental impact, and scalability. The findings intend to enrich understanding of DLE’s potential and hurdles, guiding future research in this critical technological area.

New paper published in Energy Advances from our continued collaboration with Michael Elsaesser (Paris Lodron Universität Salzburg) on carbon spherogels. Custom-designed nanoporous carbon materials enhance sustainable electrochemical technologies by offering better performance and efficiency. Carbon spherogels, which are highly porous carbon aerogel materials made up of a network of hollow carbon nanospheres with consistent diameters, are particularly promising. They offer unique advantages, including superior electrical conductivity, customizable porosity, adjustable shell thickness, and extensive surface area. In this work, we present a new, eco-friendlier approach to producing carbon spherogels using a sol-gel process that templates resorcinol-formaldehyde (RF) with polystyrene spheres in an organic solvent. By adjusting the molar ratio of resorcinol to isopropyl alcohol (R/IPA) and the polystyrene concentration, we identified the optimal conditions for creating carbon spherogels with tunable wall thicknesses. A simplified solvent exchange method from deionized water to isopropyl alcohol was developed to reduce surface tension in the gel’s pores, making this method both time and cost-efficient. The use of isopropyl alcohol, with its lower surface tension, allows for solvent extraction at room temperature and direct carbonization of RF gels with less than 20% loss in specific surface area compared to those dried supercritically. The resulting materials have specific surface areas ranging from 2300 to 3600 m2/g, as confirmed by transmission and scanning electron microscopy, which also demonstrated their uniform, hollow spherical network structure. Notably, these carbon spherogels act as high-performance electrodes for energy storage in supercapacitors, achieving a specific capacitance of up to 204 F/g at 200 mA/g with a 1 M potassium hydroxide (KOH) solution as the electrolyte.

Best practice paper on electrochemical desalination published in Cell Press Physical Science! In this paper, we shed light on technical how-to (and how-not-to) aspects of the promising future of ion-selective, energy-efficient water desalination through electrochemical methods. Including, but not limited to, capacitive deionization. We dive deep into the performance metrics commonly used for this approach and provide a comprehensive step-by-step guide on how to effectively acquire, process, and calculate raw desalination data.

We demonstrate the calculation of key performance indices (KPI), such as desalination capacity, charge efficiency, energy consumption, and ion selectivity metrics
We highlight potential pitfalls in performance metric calculations and how to avoid them
We explore the intricate relationships between pH, temperature, and conductivity, and their impact on final concentrations
We also provide a handy checklist and spreadsheet tools to streamline data processing, system design, and upscaling

This paper has been in the making for a long time. Thanks to present-day group members Mohammad Torkamanzadeh, Cansu Kök, Peter Burger, Panyu Ren, and our alumni/a Zhang Yuan, juhan lee, and 김춘수kim choonsoo.

New paper published in Journal of Molecular Liquids on binary ionic liquid supercapacitors. There is much to learn from simulation when it comes to understanding nanoscaled ion electrosorption of ions within carbon nanopores. Especially when it comes to the behavior of ionic-liquid-based supercapacitors which promise an extended potential window, and consequently, enhanced energy ratings. Ionic liquids, in absence of a solvent, and with enhanced ion-ion interactions, present an intriguing model system to study size effects in more complex electrolytes with more than just one cation. Our findings, combining simulation and experimental data, reveal the enhanced capacitance of single nanopores and nanoporous electrodes using binary electrolytes. 🔬⚡
I’d like to extend my heartfelt gratitude to our research partners (Taras Verkholyak, Dariusz GołowiczAndrij KuzmakSvyatoslav Kondrat) and my team (Anna Seltmann, Emmanuel Pameté)! And I am proud to share that this is a collaborative Polish 🔴⚪ German ⚫🔴🟡 Ukrainian paper 🔵🟡.

New open access paper published in Journal of Power Sources on an interlaboratory study on supercapacitor data evaluation. Supercapacitors are quick-charging energy savers crucial for building a strong, eco-friendly energy future. However, there’s inconsistency in reporting practices that’s hindering accurate device performance comparison within the literature. Spearheaded by our colleagues at the University of Cambridge (Jamie Gittins and Alexander Forse), the study uncovers major issues, such as the use of wrong formulas and varied interpretations of key terms, causing significant variability in data reporting.

We’ve noticed even more variation in non-ideal capacitive behavior reports. We also plaidoyer in favor of optimized machine-learning tools that automatically derive relevant key data directly from various data files under different testing conditions. Such an “approved” tool, especially when being part of open science, would enormously reduce the variation seen from today’s use of individual approaches toward supercapacitor data analysis.

Many thanks to the research participants: Jamie Gittins, Yuan Chen, Stefanie ArnoldVeronica Augustyn,
Andrea BalducciThierry BrousseElzbieta FrackowiakPedro Gomez-RomeroArchana KanwadeLukas KöpsPlawan JhaDongxun LyuMichele MeoDeepak Pandey, Le Pang, Mario Rapisarda, PhDDaniel Rueda Garcíaía, Saeed SaeedParasharam ShirageAdam ŚlesińskiFrancesca SoaviJayan ThomasMagdalena TitiriciHongxia WangZhen XuAiping YuMaiwen ZhangAlexander Forse

New paper published in Advanced Functional Materials in lead by the teams of Michael Naguib and Agnieszka Maria Jastrzębska. MBenes, a new class of post-MXene materials, stand out due to the inclusion of boron in their structure, replacing carbon and nitrogen. This distinct composition provides a fresh perspective on boron’s impact in two-dimensional materials. The challenge in processing MBenes lies in the wet-chemical etching and delamination of the initial MoAlB phase, mainly due to the strong bonding of aluminum with surrounding elements. This research successfully addresses this challenge by treating MoAlB with an aqueous HCl/H2O2 solution for varying durations of 24 hours, 48 hours, and 72 hours. The process results in individual, single-to-few layered MBene flakes, particularly notable in the 48-hour etched sample. Detailed analysis through a combination of theoretical and experimental X-ray diffraction techniques reveals that the optimally delaminated 48-MBene possesses a Mo2B2 orthorhombic lattice structure. Additionally, the formation of Mo oxide within these MBenes introduces both direct (1.2 eV) and indirect (0.2 eV) optical band gaps, significantly enhancing their photocatalytic efficiency. This is especially evident in their ability to decompose methylene blue, a commonly used organic pollutant, achieving about 90% decomposition under UV and simulated white light, with a rate thrice as fast as some MXene hybrids. Moreover, the 48-MBene shows exceptional capability in harnessing the full spectrum of visible light to generate reactive oxygen species. In contrast, the 24-hour and 72-hour treated MBenes exhibit lesser performance due to incomplete delamination or oxidation. These findings pave the way for using MBenes in environmental cleaning applications, highlighting their potential in addressing water contamination issues.

New paper published in Macromolecules on surface-initiated living anionic polymerization of functional methacrylates from the surface of organic particles.

New paper published in ACS Nano. Our work explores horn-like pore entrance geometries that boost the overall charging dynamics and charge storage of nanoporous supercapacitors. This work was in collaboration with Guang Feng (HUST).

New article published in Journal of Materials Chemistry A on high performance Mo(C,N,O)x Li-ion battery anodes. Using a continuous wet-chemical process process called a microjet reactor, we combined ammonium heptamolybdate with para-phenylenediamine, tweaking the mix to get just the right results. After applying thermal annealing, we obtained Mo(C,N,O)x with stacking defects embedded in a carbonaceous matrix. Depending on the synthesis and annealing parameters, different morphologies and phases were observed. The best of our materials yielded a high capacity of 933 mAh/g after 500 cycles! 🔋

933 mAh/g after 500 cycles… so the initial capacity must have been higher? Actually, no! On the contrary, we s tarted with about 500 mAh/g, went down a bit and then almost doubled the capacity between the 100th and 500th galvanostatic charge/discharge cycle. This has to do with the “magic of molybdenum”, as we had seen similar effects of self-activation before.🔬

Big shoutout to Mana Abdirahman Mohamed, Oliver Janka, Jörg Schmauch, and Guido Kickelbick from Universität des Saarlandes for the exciting project . 🤝 Kudos to Stefanie Arnold for her patience with this project and her excellent expertise! 🌟 And a special thanks to the Leibniz Institute for Plasma Science and Technology (INP Greifswald) e.V. (Antje Quade) for X-ray photoelectron spectroscopy. 🙌

New review article published in Advanced Energy Materials on the degradation of supercapacitors, as featured as “Editor’s Choice” and on the front cover.

Our review discusses the significance of monitoring methods and strategies for tracking the performance degradation of EDLCs and pseudocapacitors, employing a range of cutting-edge techniques such as electrochemical methods and in situ and ex situ analyses. These methods enable researchers to better understand the underlying mechanisms behind supercapacitor aging.

We also explore the intricate interplay of electrode materials, electrolytes, and other critical system aspects, including pore blocking, electrode compositions, functional groups, and corrosion of current collectors. When we understand these factors, we can pave the way for enhanced supercapacitor designs and materials that offer prolonged lifespan and improved performance. Moreover, we also examine the impact of aging from an industrial application standpoint, providing valuable insights into the real-world scenarios. And finally, we highlight future directions and challenges, including the development of innovative materials and advanced monitoring methods, to combat performance degradation effectively.

Team INM-Leibniz Institute for New MaterialsEmmanuel PametéVolker Presser
Team Friedrich Schiller University JenaLukas KöpsFabian KrethAndrea Balducci
Skeleton TechnologiesSebastian Pohlmann
Helmholtz Institute Ulm (HIU)Alberto Varzi
Nantes UniversitéThierry Brousse

New paper published in Nano Research. Heavy metal pollution is a major environmental problem to the environment and human health. Adsorption is an effective approach with a straightforward process, adaptability to a wide range of water concentrations, and high selectivity. But commonly, the materials are designed for a one-time-use and discarded after they have reached their uptake capacity.

Electrochemistry is a promising way to re-use materials by simple charge/discharge cycling. We demonstrated electrochemically enhanced selective lead removal with FeOOH. FeOOH is an environmentally friendly and cost-effective sorbent. And it is conveniently available on large scale. Our work demonstrates the feasibility of regenerating FeOOH by charge and provides a new approach for recycling and upcycling FeOOH sorbent.

Our recent study investigated the selectivity of FeOOH in a mixed solution of Co2+, Ni2+, and Pb2+ and proposed to enhance the capacity and regenerate FeOOH by using external charges. Our results demonstrated that FeOOH showed superior selectivity towards Pb2+ compared to Co2+ and Ni2+, with a purity of 97±3% in the extracts. The high selectivity is attributed to the lower activation energy for Pb2+ sorption. The system also exhibited a Pb2+ uptake capacity of 37.4 mg/g with high selectivity when using industrially exhausted granular ferric hydroxide as the electrode material.

New paper published on iron vanadate derived from Prussian Blue analog for Lithium-ion batteries in Sustainable Energy & Fuels. This marks our latest work on derivatization strategies to turn Prussian Blue Analogs (PBAs) into mixed metal oxide materials for battery applications 🔋

🔹We used PBAs as they offer a very high tunability and ease of synthesis.
🔹We successfully achieved homogeneous iron vanadate derivatization using an energy-efficient infrared furnace with CO2 gas.
🔹We entangled the active material with carbon nanotubes to generate binder-free, free-standing electrodes for direct use as electrodes.
🔹We stabilized the electrochemical performance reaching a 400 mAh/g capacity at a specific current of 250 mA/g after 150 cycles, maintaining a Coulombic efficiency of 99.2% in a potential range of 0.01-3.5 V vs. Li/Li+.
🔹The choice of electrolyte matters (of course) also, with a better performance in Li-TFSI in carbonate electrolyte compared to Li-PF6.

For an in-depth understanding of our methodology and findings, I encourage you to read the full paper where we delve deep into the role of different surfactants and the optimization of various parameters for a stable electrochemical performance.

New paper published in Small on Cu/V-Organophosphonates. In this collaborative work, we report a layered redox-active, antiferromagnetic metal organic semiconductor crystals with the chemical formula [Cu(H2O)2V(µ-O)(PPA)2] (where PPA is phenylphosphonate). 

New paper published on hydrogel-based flexible energy storage in Advanced Materials Interfaces. Our study showcases a novel electrolyte system that stands out due to its flexibility, electroactivity, and improved sustainability.
We initiated our research by electropolymerizing polypyrrole (PPy) nanotubes in graphite-thread electrodes, utilizing methyl orange templates in an acidic medium. This process successfully enhanced the conductivity, while maintaining the flexibility of the electrodes, a crucial component in developing versatile energy storage systems. We built flexible devices using hydrogel as an electrolyte prepared from poly(vinyl alcohol) (PVA)/sodium alginate (SA). This hydrogel was obtained through freeze-thawing and swelling with ionic solutions. The result was a homogenous and porous hydrogel matrix, demonstrating high conductivity of 3.6 mS/cm as-prepared and the ability of self-healing.

What sets this material apart is its adaptability. The material’s electrochemical and mechanical properties depend on the swollen electrolyte used, allowing its integration with the modified graphite-thread electrodes. This flexibility led us to develop a quasi-solid electrochemical energy storage device, with a specific capacitance value of 66 F/g at 0.5 A/g. The choice of less environmentally friendly acid electrolyte HNO3 yielded a higher capacitance in the range of 100 F/g. These attributes relied on the liquid phase in the hydrogel matrix produced from biodegradable polymers.

We thank our collaborators who were instrumental in this research project. Special acknowledgment to our esteemed colleagues from the Departamento de Química, Universidade Federal do Paraná in Brazil: Andrei Elias Deller, Izabel C. Riegel-Vidotti, and Marcio Vidotti. On our team, we are grateful for the contributions of Ph.D. student Jean Gustavo De Andrade Ruthes, our postdoc and Humboldt-Fellow Emmanuel Pameté.

The progressing electrification of water remediation: review article on electrosorption of organic compounds in Chemical Engineering Journal.
I am happy to see now-online our latest review paper, which summarizes the science and technology of electrosorption of organic compounds (EOC). Traditional methods of water treatment, such as adsorption, encounter limitations when it comes to effectively removing ionic and hydrophilic organic contaminants. Moreover, the lack of on-site regeneration techniques further hinders the efficiency of these methods. EOC not only enhances the adsorption performance but also enables green electricity-assisted regeneration of the adsorbent.
Over the past decades, the field of EOC has witnessed exponential growth in research studies. Many examples demonstrate that the application of electrical potentials can remarkably enhance the adsorption affinity, capacity, and kinetics of conductive carbon adsorbents. However, it remains unclear whether these effects are specific to certain compound classes or universally applicable, and the optimal criteria for designing EOC processes remain elusive.
In our research, we conducted a critical evaluation of the current state of the art in EOC, with a primary focus on active control of adsorption and desorption processes and their effects on both ionic and neutral organic compounds. By thoroughly considering compound speciation and surface chemistry of electrode materials, we gained mechanistic insights into the EOC process and highlighted the differences between electrosorption of inorganic and organic compounds.
We have also proposed insightful performance parameters and provided clear definitions to unify the rapidly expanding research in the EOC field. By doing so, we aim to establish a foundation for consistent analysis and evaluation of EOC techniques. Furthermore, we discuss potential application scenarios and outline future research directions to guide the development of this exciting technology. EOS, thereby, is not a one-size-fits-all solution for removing contaminants. However, it offers a valuable tool, particularly for tackling the challenges posed by hydrophilic and ionic organic contaminants, which often prove difficult for conventional adsorption processes.
Thanks to the great team of scientists authoring the work from the Helmholtz Centre for Environmental Research (UFZ): Navid SaeidiFalk Harnisch, Franz-Dieter Kopinke, Anett Georgi

New work published in Carbon in collaboration with Prof. Choonsoo Kim. In our research, we explore the impact of different carbon types on desalination capacity and rate. We exemplify the impact of conventional carbon black, nanoscaled carbon onions, and micro-mesoporous carbons. In the early cycles, we observed that using AC electrodes without additives resulted in a higher desalination capacity, reaching approximately 10 mg/g. However, there was a trade-off: the desalination rate was slightly lower. It turns out that larger AC particles limited the transportation of ions within the electrode due to the increased diffusion path length.

By incorporating small and less porous additives, we achieved the highest desalination rate (20 μg/g/s) as the additive particles reduced the ion diffusion path length by increasing size dispersion, thus enhancing overall ion transport and desalination rates.