New paper published in Electrochimica Acta on Ni-decorated AgAu alloy graphene/cobalt hydroxide electrodes for micro-supercapacitors to obtain high-performance micro-supercapacitors. A nanocomposite of graphene, cobalt hydroxide and nickel can was obtained from using gold-silver alloy lines. Using a two-step electrodeposition method, the scaly morphology is pre-deposited on a Ni film, followed by the interconnecting corrugated graphene/cobalt hydroxide composite nanomaterial. The resulting device, a graphene/cobalt hydroxide/Ni//activated carbon flexible micro-supercapacitor (MSC), was assembled by gel KOH-PVA electrolyte, graphene/cobalt hydroxide/Ni (positive electrode), and activated carbon (negative electrode). When testing, we obtained a volumetric energy of about 19 mWh/cm3 and the devices retained over 94% capacitance after 10,000 cycles. After 1,000 continuous bending/unbending cycles at a 180° bending angle with the frequency of 100 mHz, the capacitance retention of MSC is still maintained at 97% of the initial value.
Welcome to our new Postdoc Dr. Kaitlyn Prenger! Kaitlyn is a graduate of Tulane University from the esteemed team of Michael Naguib and will work on novel 2D (and other) materials for sustainable electrochemical applications.
Stefanie Arnold gives an oral presentation with the title “Design Matters: The Path to High-Performance Antimony / MXene Hybrid Electrodes for Sodium-Ion Batteries” at the MSE2022 conference in Darmstadt. This was joint work with Riccardo Ruffo‘s team and Stefano Marchionna (Italy).
new paper published in ACS Energy Letters on continuous electrochemical lithium-ion extraction. We used a redox electrolyte “engine” to drive the ion transfer (in our case: potassium ferricyanide). Employing a pair of ceramic lithium superionic conductor (LISICON) membranes meant that only Lithium ions were accessible to the redox electrolyte for charge compensation. And to complement the design, we used an anion exchange membrane to separate the inflow (e.g., seawater) from a recovery solution. By this way, we obtained an electrochemical system for the continuous extraction of Lithium ions. This sets this technology apart from earlier works (including our contributions) that relied on a cyclic operation to obtain ion separation. Yet, this is just one of many more steps towards seeing such technology toward application; future research must critically address cell design, optimization of the Li-membranes, and investigating the robustness and durability of continuous operation.
This work was the result of the collaboration of our Ph.D. students Lei Wang, Stefanie Arnold, Panyu Ren, and our former Postdoc (now group leader at Bavarian Center for Battery Technology (BayBatt)) Qingsong Wang, as well as our Chinese collaborators Jun Jin and Zahoyin Wen (Chinese Academy of Sciences).
New paper published in Materials Futures. Sodium-deficient, P2-type layered oxides are promising cathodes for sodium-ion batteries. Their open sodium cation transport pathways lead to low diffusion barriers and enable high charge/discharge rates. However, a phase transition from P2 to O2 structure occurring above 4.2 V and metal dissolution at low potentials upon discharge results in rapid capacity degradation. In this work, we demonstrate the positive effect of configurational entropy on the stability of the crystal structure during battery operation. The high-entropy cathode material shows lower structural transformation and Mn dissolution upon cycling in a wide voltage range from 1.5 V to 4.6 V. Advanced operando techniques and post-mortem analysis were used to thoroughly probe the underlying reaction mechanism. Overall, the high-entropy strategy is a promising route for improving the electrochemical performance of P2 layered oxide cathodes for advanced sodium-ion battery applications.
New paper published in Desalination on the ion selectivity of carbon nanopores. It is well known that electrolyte confinement inside carbon nanopores strongly affects ion electrosorption in capacitive deionization. A thorough understanding of the intricate pore size influence enables enhanced charge storage performance and desalination in addition to ion separation. In subnanometer pores, where the pore size is smaller than hydrated ion size, a dehydration energy barrier must be overcome before the ions can be electrosorbed into the pores. Ion sieving is observed when the dehydration energy is larger than the applied energy. However, when a high electrochemical potential is used, the ions can desolvate and enter the pores. Capitalizing on the difference in size and dehydration energy barriers, this work applies the subnanometer porous carbon material, and a high electrochemical ion selectivity for Cs+ and K+ over Na+, Li+, Mg2+, and Ca2+ is observed. This establishes a viable way for selective heavy metal removal by varying pore and solvated ion sizes. Our work also shows the transition from double-layer capacitance to diffusion-limited electrochemical features in narrow ultramicropores.
Behnoosh Bornamehr gives an oral presentation on her research on electrospinning. Her talk is aptly titled “Too fast, too brittle: a study on heat treatment parameters for free-standing vanadium oxide electrodes”.
Welcome new Ph.D. student Jean Gustavo De Andrade Ruthes! Jean is from the Universidade Federal do Paraná, Brazil, and will be working on MXene / graphene batteries within our Czech-German research collaboration.
Welcome visiting student Esmeralda Lopez Toro! Esmeralda is from the Universidad de Santiago de Chile and will work with us on electrospinning.
Welcome new Postdoc Dr. Delvina Japhet Tarimo! Delvina is from University of Pretoria, South Africa, and will be working on nanoporous materials and next-generation batteries.
Welcome to our new student intern, Anna Quinten! Anna is from Saarland University and will be working on ionic liquid supercapacitors.
Chandrasekaran Sakthi Vigneshwaran is a Master student working on next-generation Prussian blue based electrode materials for advanced batteries. Congratulations on being awarded a three month fellowship by the StudienStiftungSaar!
New paper published in Current Opinion in Green and Sustainable Chemistry on “Recent advances in wastewater treatment using semiconductor photocatalysts”. Can’t decide if you like water remediation or photocatalysis/semiconductors more? They both make a great match! Read about synergies and future possibilities in our latest review article in Current Opinion in Green and Sustainable Chemistry. The team of Prof. Xiao Su (Jaeyoung Hong & Ki-Hyun Cho) and I explore this interesting interfacial research – interfacial in double meaning: at the interface of fluid and solid, and at the interface of material science/electrochemistry and water research. It is exciting to explore semiconductors, for example, to target emerging contaminants, such as perfluorinated compounds.
Dr. Samantha Husmann will attend the prestigious 2022 Lindau Nobel Laureate Meeting this week. She is one of only 611 young scientists selected in a highly competitive process from across the globe. This year, the topic is chemistry, perfectly reflected by Samantha’s research on next generation electrochemical materials (including, but not limited to, Prussian blue and Prussian blue analogues). Her positive energy and visionary research perspective will enrich the LINO22!
Mohammad Torkamanzadeh gives an oral presentation entitled “MXene for Electrochemical Water Desalination” at the 15th International Ceramics Congress CIMTEC in Perugia, Italy.
.
Immensely proud of my former Ph.D. student and now Dr. Yuan Zhang for being awarded the prestigious Feodor Lynen Fellowship from the Alexander von Humboldt Foundation! She will join the team of Yury Gogotsi and her work will relate to MXene. Looking forward to strengthening also trilateral opportunities between the US, China, and Germany!
New paper entitled “Spray-dried pneumococcal membrane vesicles are promising candidates for pulmonary immunization” published in the International Journal of Pharmaceutics. This collaborative work spearheaded by experts from the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) and Saarland University explores optimized vaccine microparticles with a mean particle size of 1–2 µm, corrugated surface, and nanocrystalline nature.
5.3 Million seconds. 87,660 hours. 10 years. But who is counting😅
Time flies by fast when you are busy. Today marks the 10-year anniversary of the Energy Materials Group, my work family, and home away from home. Starting after returning from Yury Gogotsi‘s team (where I served as Humboldt Fellow and Research Assistant Professor) on June 1st, 2012, I had the privilege of creating my own group thanks to a 3.6 M€ starting grant from Bundesministerium für Bildung und Forschung at the INM-Leibniz Institute for New Materials. We quickly diversified in topics at the energy/water research nexus, ranging now from supercapacitors to batteries, from capacitive deionization to desalination fuel cells, from ionic charge storage to ion separation. A strong backbone of our team is the ability to go all the way from material synthesis and characterization to in situ testing and (small) device benchmarking. I am grateful to our teams many alumni and alumnae, the wonderful people in our current great team, and the amazing people I am yet to meet and work with. I am very grateful to our collaborators and partners in research and science. I will abstain from giving a complete list, but I would be amiss not to mention a few very special collaborators (in alphabetical order): Doron Aurbach, Veronica Augustyn, Guang Feng, Markus Gallei, Yury Gogotsi, Frank Mücklich, Michael Naguib, Christian Prehal, Patrice Simon, Matthew Suss.
What will we be working on over the course of the next 10 years? I always tell students: the topic you may become famous for may be on a material who you have not hear from yet 😉 So I will refrain from any specific speculation here since we all know “time makes fools out of us all”. We will continue to advance our research on sustainable materials, energy materials recycling, control over ion selectivity, and high performance beyond-lithium energy storage technologies. And to push forward with our industry collaborators to transfer our next-next-generation materials and processes into applications. I cannot wait for it!
Let me close with a few accomplishments of our team from the last 10 years:
220 Peer review publications
6 Nature publishing group publications
16,489 total citations (23,662 if you include <2012)
19 Current group members
68 Alumni and alumnae
158 Conference presentations
45 Seminar talks
78 Poster presentations
53 H-index (60 if you include <2012)
10 Finished Ph.D. Theses
15 Finished Master Theses
5 Finished Bachelor Theses
9,793,132 € in research funding
4 Fellowships for the Lindau Nobel Laureate Meeting
1 ARCHES award
1 Bayer Foundation award
1 Leibniz Dissertation award
1 Umsicht Science award
Stefanie Arnold gives an oral presentation entitled “Design of High-Performance Antimony / MXene Hybrid Electrodes for Sodium-Ion Batteries”. Her talk on June 1st, 3 PM local time, is part of the Symposium A01 on batteries. This work is the latest outcome of our collaboration with the group and team of Riccardo Ruffo (Università degli Studi di Milano-Bicocca) and Stefano Marchionna (Ricerca sul Sistema Energetico). Special thanks to visiting Ph.D. student Antonio Gentile from Riccardo’s team!
Welcome visiting Ph.D. student Soghra Ghorbanzadeh! Soghra comes from the Hakim Sabzevari University and will be working on electroactive interfaces of 2D materials in the context of sustainable water technologies.