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 Arnold, Veronica Augustyn,
Andrea Balducci, Thierry Brousse, Elzbieta Frackowiak, Pedro Gomez-Romero, Archana Kanwade, Lukas Köps, Plawan Jha, Dongxun Lyu, Michele Meo, Deepak Pandey, Le Pang, Mario Rapisarda, PhD, Daniel Rueda Garcíaía, Saeed Saeed, Parasharam Shirage, Adam Ślesiński, Francesca Soavi, Jayan Thomas, Magdalena Titirici, Hongxia Wang, Zhen Xu, Aiping Yu, Maiwen Zhang, Alexander Forse

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 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 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 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 Saeidi, Falk 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.