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 Materials: Emmanuel Pameté, Volker Presser
Team Friedrich Schiller University Jena: Lukas Köps, Fabian Kreth, Andrea Balducci
Skeleton Technologies: Sebastian Pohlmann
Helmholtz Institute Ulm (HIU): Alberto Varzi
Nantes Université: Thierry Brousse

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 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.

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.

New paper published in a special issue of Energy Technology on battery research ontology. This work offers a logical framework that seamlessly integrates with digital architecture, enabling efficient visualization, correlation, and prediction capabilities in battery production, research, and development.

The ontology employs a predetermined terminology to specify materials and processes, establishing a chain of unit processes that connect raw materials to the final products of battery cell production. Moreover, it facilitates the attachment of analytical methods, known as characterization methods, to the relevant items. To ensure its suitability for both industrial-scale and laboratory-scale data generation and implementation, extensive workshops and interviews with battery materials and production process experts were conducted during its development.

The ontology encompasses the identification and definition of raw materials and intermediate products across all production steps, ultimately leading to the creation of the battery cell. Standard materials and process chains serve as the foundation for defining steps and items using commonly used terms. Furthermore, the research explores alternative structures and the integration of the ontology with existing ontologies.

New paper published in Advanced Materials Interfaces on mechanisms in high-performance tin oxide / MXene batteries. As the demand for power and energy storage continues to grow, we researchers are constantly exploring new ways to improve battery performance. One promising approach involves using conversion/alloying materials, such as tin oxide, to design high-performance lithium-ion batteries. While these materials show excellent performance and ease of preparation, they often suffer from mechanical instabilities during cycling that limits their usefulness. This issue can be addressed (and overcome) by combining tin oxide with MXene.
In this study, we prepared a 50/50 (by mass) tin oxide / Ti-MXene (SnO₂/Ti₃C₂T_z) nanocomposite and optimized it as a negative electrode for lithium-ion batteries. The result? A nanocomposite that delivers over 500 mAh/g for 700 cycles at 0.1 A/g and demonstrates excellent rate capability, with 340 mAh/g at 8 A/g.
The success of this nanocomposite lies in the synergistic behavior of its two components, which we confirmed through ex situ chemical, structural, and morphological analyses. Not only does this knowledge allow us to formulate a reaction mechanism with lithium-ions that provides partial reversibility of the conversion reaction, but it also opens up new possibilities for designing high-performance lithium-ion batteries.

Thanks to our great team of collaborators:

Team Ricerca sul Sistema Energetico – RSE SpA & Università degli Studi di Milano-Bicocca:
Antonio Gentile
Chiara Ferrara
Stefano Marchionna
Riccardo Ruffo

Team INM-Leibniz Institute for New Materials:
Stefanie Arnold
Volker Presser

Team Karlsruhe Institute of Technology (KIT)
Yushu Tang
Julia Maibach
Christian Kübel

New paper published in npj Materials Degradation (open access). In cooperation with the group of Frank Mücklich at Saarland University and partners, we have found that coating laser-patterned stainless-steel surfaces with carbon nanotubes (CNT) or carbon onions (CO) can create an effective solid lubrication system. By storing the particles inside the pattern, lubricant retention is improved and depletion in the contact area is prevented. In previous works, we used laser interference patterning to create line patterns with different depths and coated them with CNTs or COs. Friction tests were conducted to study the effect of structural depth on the lubricity of these surfaces, and we found that shallower textures result in lower friction coefficients. Our latest study examines the degradation of the carbon nanoparticles on substrates with different structural depths, and Raman characterization shows severe degradation of both particle types. This degradation is classified within Ferrari’s three-stage amorphization model. Electron microscopy also confirms that CNT lubricity is improved at the cost of increasing particle defectivity, while CO-derived tribofilms experience even more substantial structural degradation.

Our research team has published an article in ChemSusChem on the promising use of stable and efficient SnO₂ electrodes for degrading refractory organic pollutants in wastewater treatment. Our approach involved the preparation of Ti³⁺ self-doped urchin-like rutile TiO₂ nanoclusters (TiO_2-xNCs) on a Ti mesh substrate using hydrothermal and electroreduction methods, which served as an interlayer for the deposition of Sb-SnO₂. Our TiO_2-xNCs/Sb-SnO₂ anode exhibited a high oxygen evolution potential and strong *OH generation ability, resulting in improved degradation performance for rhodamine B, methylene blue, alizarin yellow R, and methyl orange. Our unique rutile interlayer also extended the anode lifetime sixfold due to its good lattice match with SnO₂ and three-dimensional concave-convex structure. Overall, our work highlights the importance of designing interlayer crystal forms and structures for achieving efficient and stable SnO₂ electrodes in addressing dye wastewater problems. This work was done in collaboration with our colleagues from Chongqing University.

New perspective paper published in Communications Materials. The high entropy concept is ideally suited for MXenes but also capable to be a unique tool to tailor and improve electrochemical properties in other materials.

Multiple principal element or high-entropy materials have recently been studied in the two-dimensional (2D) materials phase space. These promising classes of materials combine the unique behavior of solid-solution and entropy-stabilized systems with high aspect ratios and atomically thin characteristics of 2D materials. The current experimental space of these materials includes 2D transition metal oxides, carbides/carbonitrides/nitrides (MXenes), dichalcogenides, and hydrotalcites. However, high-entropy 2D materials have the potential to expand into other types, such as 2D metal-organic frameworks, 2D transition metal carbo-chalcogenides, and 2D transition metal borides (MBenes).

So, what is our perspective article about? We discuss the entropy stabilization from bulk to 2D systems, the effects of disordered multi-valent elements on lattice distortion and local electronic structures and elucidate how these local changes influence the catalytic and electrochemical behavior of these 2D high-entropy materials. We also provide a perspective on 2D high-entropy materials research and its challenges and discuss the importance of this emerging field of nanomaterials in designing tunable compositions with unique electronic structures for energy, catalytic, electronic, and structural applications.

This perspective paper has been the result of our collaboration with my dear friend Babak Anasori (with his team: Kartik Nemani and Brian Wyatt) from Purdue University and our team (including Mohammad Torkamanzadeh).

New paper published in the Journal of the American Ceramic Society on the synthesis of new hybrid electrode materials for Li-ion batteries (LIBs). Through controlled oxidation of layered Ti₂SnC, we were able to obtain TiO₂-SnO₂-C/carbide hybrid materials using two different methods: partial oxidation in an open-air furnace (OAF) and rapid thermal annealing (RTA). The resulting carbide phase included both residual Ti₂SnC and TiC as a reaction product. In testing, we found that the sample oxidized in the OAF at 700°C for 1 hour had the highest initial lithiation capacity of 838 mAh/g at 100 mA/g. However, its delithiation capacity decreased to 427 mAh/g over cycling. In contrast, the RTA sample treated at 800°C for 30 seconds demonstrated the most efficient performance, with a reversible capacity of approximately 270 mAh/g after 150 cycles and a specific capacity of about 150 mAh/g under high cycling rate (2000 mA/g). Our findings suggest that this processing method could have wide-ranging applications in energy storage, particularly for other members of the MAX family. This work was the latest product of collaboration with the team of Michael Naguib (Tulane University, USA).