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The Many Deaths of Supercapacitors: Degradation, Aging, and Performance Fading
Get PDFHigh-performance electrochemical applications have expedited the research in high-power devices. As such, supercapacitors, including electrical double-layer capacitors (EDLCs) and pseudocapacitors, have gained significant attention due to their high power density, long cycle life, and fast charging capabilities. Yet, no device lasts forever. It is essential to understand the mechanisms behind performance degradation and aging so that these bottlenecks can be addressed and tailored solutions can be developed. Herein, the factors contributing to the aging and degradation of supercapacitors, including electrode materials, electrolytes, and other aspects of the system, such as pore blocking, electrode compositions, functional groups, and corrosion of current collectors are examined. The monitoring and characterizing of the performance degradation of supercapacitors, including electrochemical methods, in situ, and ex situ techniques are explored. In addition, the degradation mechanisms of different types of electrolytes and electrode materials and the effects of aging from an industrial application standpoint are analyzed. Next, how electrode degradations and electrolyte decompositions can lead to failure, and pore blocking, electrode composition, and other factors that affect the device's lifespan are examined. Finally, the future directions and challenges for reducing supercapacitors' performance degradation, including developing new materials and methods for characterizing and monitoring the devices are summarized
(Hybrid-)Batteriematerialien der nächsten Generation an der Schnittstelle zwischen Wasser, Energie und Recycling
No full textTransitioning toward large-scale utilization of renewable energy necessitates environmentally friendly energy storage technology. Especially for electrochemical energy storage, it is imperative to develop electrode materials with higher performance, better recyclability, and improved environmental friendliness. Such next-generation materials and technologies not only allow for enhanced energy storage but also enable electrochemical desalination to generate clean, potable water or recover precious elements, such as lithium ions. This thesis develops novel (hybrid) materials for the energy/water/recycling nexus. Careful material design and optimization enable improved electrochemical performance of intercalation, alloying, and conversion electrodes for lithium-ion and sodium-ion battery electrodes. For example, members of the large 2D material family MXene yield high-performance electrodes when hybridized with SnO2 or Sb, or when their interlayer space is carefully adjusted. Their 2D nature allows also a new approach to facile electrode recycling. Next-generation water remediation is explored by adopting, for the first time, an alloying material (Sb), hollow-cube cobalt hydroxide, and seawater batteries. Selective lithium extraction is demonstrated by combining a redox flow battery with a Li-selective ceramic membrane to harvest lithium ions directly from (synthetic) seawater.Der Übergang zu einer groß angelegten Nutzung erneuerbarer Energien erfordert eine umweltfreundliche Energiespeichertechnologie. Insbesondere für die elektrochemische Energiespeicherung ist es unerlässlich, Elektrodenmaterialien mit höherer Leistung, besserer Wiederverwertbarkeit und verbesserter Umweltfreundlichkeit zu entwickeln. Solche Materialien und Technologien der nächsten Generation ermöglichen nicht nur eine verbesserte Energiespeicherung, sondern auch die elektrochemische Entsalzung zur Erzeugung von sauberem Trinkwasser oder die Rückgewinnung wertvoller Elemente wie Lithium-Ionen. Im Rahmen dieser Arbeit werden neuartige (hybride) Materialien an der Schnittstelle zwischen Energie, Wasser und Recycling entwickelt. Sorgfältiges Materialdesign und -optimierung ermöglichen eine verbesserte elektrochemische Leistung von Interkalations-, Legierungs- und Umwandlungselektroden für Lithium-Ionen- und Natrium-Ionen-Batterieelektroden. Die Vertreter der großen 2D-Materialfamilie MXene beispielsweise liefern Hochleistungselektroden, wenn sie mit SnO2 oder Sb kombiniert werden oder wenn ihr Zwischenschichtabstand sorgfältig angepasst wird. Ihre 2D-Natur ermöglicht auch einen neuen Ansatz für ein einfaches Elektrodenrecycling. Die nächste Generation der Wasseraufbereitung wird erforscht, indem zum ersten Mal ein Legierungsmaterial (Sb), Kobalthydroxid Hohlwürfel und Meerwasserbatterien eingesetzt werden. Die selektive Lithiumextraktion wird durch die Kombination einer Redox-Flow-Batterie mit einer Li-selektiven Keramikmembran demonstriert, um Lithiumionen direkt aus (synthetischem) Meerwasser zu gewinnen
Vacancy diffusion and its consequences for void growth at the interface of a stripping metal electrode and solid electrolyte
Get PDFIt is commonly observed that voids can nucleate and grow in the lithium anode of a solid state Li-ion battery at a location adjacent to the solid electrolyte during the stripping (discharge) phase of the battery; a similar phenomenon is observed in sodium-based batteries. It is hypothesised in the current literature that the formation of these voids is due to the coalescence of vacancies that have been generated at the electrode/electrolyte interface when metal atoms are oxidized and transported into the electrolyte: the slow diffusion of the vacancies away from the electrolyte interface into the adjacent electrode results in their coalescence and the consequent growth of voids. These hypotheses are challenged in the current study by using the Onsager formalism to generate a variational principle for vacancy diffusion. Our analysis reveals that no driving force exists for the diffusion of vacancies into a homogeneous metal electrode that thins by stripping. This finding is contrary to models in the literature which have mistakenly assumed that the vanishing flux at the current collector prevents rigid body motion (drift) of the electrode which in turn prevents thinning of the electrode during stripping. Based on our analysis, we conclude that vacancy diffusion within a homogeneous electrode is not responsible for the nucleation and growth of voids at the interface between a stripping metal electrode and a solid electrolyte
Hydrogel-Based Flexible Energy Storage Using Electrodes Based on Polypyrrole and Carbon Threads
Get PDFDeveloping new flexible and electroactive materials is a significant challenge to producing safe, reliable, and environmentally friendly energy storage devices. This study introduces a promising electrolyte system that fulfills these requirements. First, polypyrrole (PPy) nanotubes are electropolymerized in graphite-thread electrodes using methyl orange (MO) templates in an acidic medium. The modification increases the conductivity and does not compromise the flexibility of the electrodes. Next, flexible supercapacitors are built using hydrogel prepared from poly(vinyl alcohol) (PVA)/sodium alginate (SA) obtained by freeze–thawing and swollen with ionic solutions as an electrolyte. The material exhibits a homogenous and porous hydrogel matrix allowing a high conductivity of 3.6 mS cm−1 as-prepared while displaying great versatility, changing its electrochemical and mechanical properties depending on the swollen electrolyte. Therefore, it allows its combination with modified graphite-thread electrodes into a quasi-solid electrochemical energy storage device, achieving a specific capacitance (Cs) value of 66 F g−1 at 0.5 A g−1. Finally, the flexible device exhibits specific energy and power values of 19.9 W kg−1 and 3.0 Wh kg−1, relying on the liquid phase in the hydrogel matrix produced from biodegradable polymers. This study shows an environment friendly, flexible, and tunable quasi-solid electrolyte, depending on a simple swell experiment to shape its properties according to its application
Impact of mucus modulation b N-acetylcysteine on nanoparticle toxicity
Get PDFHuman respiratory mucus is a biological hydrogel that forms a protective barrier for the underlying epithelium. Modulation of the mucus layer has been employed as a strategy to enhance transmucosal drug carrier transport. However, a drawback of this strategy is a potential reduction of the mucus barrier properties, in particular in situations with an increased exposure to particles. In this study, we investigated the impact of mucus modulation on its protective role. In vitro mucus was produced by Calu-3 cells, cultivated at the air-liquid interface for 21 days and used for further testing as formed on top of the cells. Analysis of confocal 3D imaging data revealed that after 21 days Calu-3 cells secrete a mucus layer with a thickness of 24 ± 6 μm. Mucus appeared to restrict penetration of 500 nm carboxyl-modified polystyrene particles to the upper 5–10 μm of the layer. Furthermore, a mucus modulation protocol using aerosolized N-acetylcysteine (NAC) was developed. This treatment enhanced the penetration of particles through the mucus down to deeper layers by means of the mucolytic action of NAC. These findings were supported by cytotoxicity data, indicating that intact mucus protects the underlying epithelium from particle-induced effects on membrane integrity. The impact of NAC treatment on the protective properties of mucus was probed by using 50 and 100 nm amine-modified and 50 nm carboxyl-modified polystyrene nanoparticles, respectively. Cytotoxicity was only induced by the amine-modified particles in combination with NAC treatment, implying a reduced protective function of modulated mucus. Overall, our data emphasize the importance of integrating an assessment of the protective function of mucus into the development of therapy approaches involving mucus modulation
Direct Ink Writing of Nanocellulose and PEDOT:PSS for Flexible Electronic Patterned and Supercapacitor Papers
Get PDFPrinted electronic paper identifies its interest in flexible organic electronics and sustainable and clean energy applications because of its straightforward production method, cost-effectiveness, and positive environmental impact. However, current limitations include restricted material thickness and the use of supporting substrate for printing. Here, 2D and 3D electronic patterned paper are fabricated from direct ink writing (DIW) nanocellulose and PEDOT:PSS-based materials using syringe deposition and 3D printing. The conductor patterns are integrated in the bulk of the paper, while non-conductive sections are used as support to form free-standing paper. The strong interface between the patterns of electronic patterned paper gives mechanical stability for practical handling. The conductive paper-based electrode has 202 S cm−1 and is capable of handling electric current up to 0.7 A, which can be used for high-power devices. Printed supercapacitor papers show high specific energy of 4.05 Wh kg−1, specific power of 4615 W kg−1 at 0.06 A g−1, and capacitance retention above 95% after 2000 cycles. The new design structure of electronic patterned papers presents a solution for additive manufacturing of paper-based composites for supercapacitors, wearable electronics, or sensors for smart packaging
On the significance of Elastic Coupling for Stresses and Leakage in Frictional Contacts
Get PDFWe study how the commonly neglected coupling of normal and in-plane elastic response affects tribological properties when Hertzian or randomly rough indenters slide past an elastic body. Compressibility-induced coupling is found to substantially increase maximum tensile stresses, which cause materials to fail, and to decrease friction such that Amontons law is violated macroscopically even when it holds microscopically. Confinement-induced coupling increases friction and enlarges domains of high tension. Moreover, both types of coupling affect the gap topography and thereby leakage. Thus, coupling can be much more than a minor perturbation of a mechanical contact
Discovery of a high-performance phage-derived promoter/repressor system for probiotic lactobacillus engineering
Get PDFBackground The Lactobacillus family comprises many species of great importance for the food and healthcare industries, with numerous strains identified as beneficial for humans and used as probiotics. Hence, there is a growing interest in engineering these probiotic bacteria as live biotherapeutics for animals and humans. However, the genetic parts needed to regulate gene expression in these bacteria remain limited compared to model bacteria like E. coli or B. subtilis. To address this deficit, in this study, we selected and tested several bacteriophage-derived genetic parts with the potential to regulate transcription in lactobacilli.
Results We screened genetic parts from 6 different lactobacilli-infecting phages and identified one promoter/repressor system with unprecedented functionality in L. plantarum WCFS1. The phage-derived promoter was found to achieve expression levels nearly 9-fold higher than the previously reported strongest promoter in this strain and the repressor was able to almost completely repress this expression by reducing it nearly 500-fold.
Conclusions The new parts and insights gained from their engineering will enhance the genetic programmability of lactobacilli for healthcare and industrial applications
Annual report 2022 / Leibniz Institute for New Materials
Get PDFDas Institut blickt wieder auf ein erfolgreiches Jahr zurück. Beispiele aus den wissenschaftlichen Highlights umfassen Technologien zur Wasserentsalzung mit Kohlenstoffelektroden, die Entwicklung medizinischer Hydrogele zur Wachstumssteuerung eingeschlossener Bakterien, oder den Einbau von maschinellem Lernen in neue Greifsysteme.
Zum Jahresende 2022 wurde Herr Professor Eduard Arzt in den Ruhestand verabschiedet. Als Wissenschaftlicher Geschäftsführer und Vorsitzender der Geschäftsführung hat er die Entwicklung des INM in den letzten 15 Jahren maßgeblich geprägt und das Institut zu weltweiter Anerkennung geführt.
Mit Dr. Sara Trujillo und Dr. Oskar Staufer starteten zwei Nachwuchsforschende. Ihre Gruppen verstärken die Aktivitäten im Bereich Lebende Therapeutische Materialien und die Kooperation mit den Lebenswissenschaften auf dem Campus. Mit Dr. Cao Nguyen Duong erweiterte das INM seine Serviceleistungen auf dem Gebiet der Fluoreszenzmikroskopie. Prof. Niels de Jonge, seit 2012 Leiter des Programmbereichs Innovative Elektronenmikroskopie, verließ das INM, um eine leitende Position in der Industrie zu übernehmen.
Auch in diesem Jahr gab es wieder viele Auszeichnungen für INM-Mitarbeitende. Stellvertretend seien hier genannt: Prof. Volker Presser erhielt den Umwelt- und Klimaschutzpreis der Stadt Saarbrücken. Frau Kathrin Schmitt wurde der Auszubildendenpreis der Leibniz-Gemeinschaft verliehen. Für Dr. Emmanuel Pammete und Dr. Yuan Zhang war das INM wieder Gastgeber im Rahmen der Alexander-von-Humboldt-Stiftung.
Die mit Mitteln des Landes und des Bundes geförderte Umbaumaßnahme inkl. des Sondertatbestandes sind bereits erolgreich umgesetzt. es konnte damit für die Zukunft eine hervorragende Infrastruktur für die Forschung am INM geschaffen werden
Growth of titania and tin oxide from Ti2SnC via rapid thermal oxidation in air for lithium-ion battery application
Get PDFHerein, we report the synthesis of TiO2–SnO2–C/carbide hybrid electrode materials for Li-ion batteries (LIBs) via two different methods of controlled oxidation of layered Ti2SnC. The material was partially oxidized in an open-air furnace (OAF) or using a rapid thermal annealing (RTA) approach to obtain the desired TiO2–SnO2–C/carbide hybrid material; the carbide phase encompassed both residual Ti2SnC and TiC as a reaction product. We tested the oxidized materials as an anode in a half cell to investigate their electrochemical performance in LIBs. Analysis of the various oxidation conditions indicated the highest initial lithiation capacity of 838 mAh/g at 100 mA/g for the sample oxidized in the OAF at 700°C for 1 h. Still, the delithiation capacity dropped to 427 mAh/g and faded over cycling. Long-term cycling demonstrated that the RTA sample treated at 800°C for 30 s was the most efficient, as it demonstrated a reversible capacity of around 270 mAh/g after 150 cycles, as well as a specific capacity of about 150 mAh/g under high cycling rate (2000 mA/g). Given the materials’ promising performance, this processing method could likely be applied to many other members of the MAX family, with a wide range of energy storage applications