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Designing Functional Polymeric Materials for High Capacity Lithium-Sulfur Batteries

English title Designing Functional Polymeric Materials for High Capacity Lithium-Sulfur Batteries
Applicant Coskun Ali
Number 188572
Funding scheme Project funding (Div. I-III)
Research institution Département de Chimie Université de Fribourg
Institution of higher education University of Fribourg - FR
Main discipline Material Sciences
Start/End 01.02.2020 - 31.01.2024
Approved amount 638'666.00
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All Disciplines (2)

Discipline
Material Sciences
Organic Chemistry

Keywords (5)

Energy Storage; Polysulfide shuttling; Li-ion Battery; Sulfur; Polymerization

Lay Summary (German)

Lead
Intermittent nature of renewable energy sources necessitates the development of high-capacity, low-cost energy storage systems such as Lithium sulfur batteries. In addition, these systems could also benefit further development of electric vehicles. This project targets the fundamental understanding of the Lithium sulfur batteries along with the development of new sulfur rich polymers as cathode materials.
Lay summary

Eine erhöhte Umweltbelastung durch anthropogenen Kohlenstoffdioxid Emissionen von grossen Industrieanlagen wie Kohlekraftwerken, förderte die Entwicklung von erneuerbaren, umweltverträglichen Energietechnologien. Ihre diskontinuierliche Veranlagung benötigt aber einer gleichzeitigen Entwicklung von hohen Energiedichten und kostengünstigen Energiespeichern. Zum Beispiel: Solarenergie wird während des Tages generiert, die erzeugte Energie könnte aber in der Nacht eine höhere Nachfrage stillen. Dafür ist die Entwicklung von kommerziell rentablen, günstigen, Hochleistungsbatterien erforderlich. Die Lithium-Schwefel (Li-S) Batterien stellen aufgrund Ihrer aussergewöhnlichen theoretischen Kapazität, welche zwei- bis viermal höher ist als bei herkömmlichen Lithium-Ion Batterien, einer der vielversprechendsten Kandidaten der nächsten Generation Akkumulatoren dar. Technologische Fortschritte in diesem Gebiet werden die Verwendung von kostengünstigen Rohstoffen wie Schwefel für fortgeschrittene Energiespeicher ermöglichen und zur Entwicklung von elektrischen Fahrzeugen und Smart Grid Systemen beitragen. Die vorgeschlagene Forschung ermöglicht einen massgeblichen Fortschritt für die Entwicklung von Li-S Batterie Technologien. Durch das Verständnis der zugrundeliegenden Mechanismen kann das volle Potential der Li-S Batterien verwirklicht werden. Darüber hinaus werden Befunde dieser Forschung eine solide Basis für Energiespeicher in der Schweiz schaffen und somit dringliche ökologische Herausforderungen angehen.

Direct link to Lay Summary Last update: 03.12.2019

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
202296 Pushing All Solid-State Batteries to Their Full Potential - Interface Engineering Guided by Advanced Diagnostics for High Performance Scalable Batteries 01.01.2022 Sinergia
198110 600 MHz Nuclear Magnetic Resonance Spectrometer 01.03.2021 R'EQUIP

Abstract

Environmental problems originating from anthropogenic CO2 emissions from large point sources, such as coal-power plants, promoted the development of eco-friendly renewable energy technologies. However, their intermittent nature necessitates the simultaneous development of high energy density, low-cost energy storage systems. The lithium-sulfur (Li-S) battery is among the most promising candidates as a next generation battery due to its exceptional theoretical gravimetric capacity of 1600 mAh g-1 and an energy density of 2600 Wh kg-1, which is 2-4 times higher compared to the conventional LIBs. Although the research on the Li-S batteries have been going for almost two decades, there are still fundamental problems yet to be tackled. The problems include (1) insulating nature of elemental sulfur, sulfur reduction intermediates and Li2S, (2) dendrite formation on the Li-metal anode surface, (3) volume expansion during lithiation up 80% and (4) the dissolution of Li-polysulfides (Li-PS) in the electrolyte, which serves as a redox shuttle leading to a severe capacity decay. Among these issues, the most critical one is the dissolution of Li-PS in the electrolyte and its diffusion as well as the side reactions with Li-metal anode and the electrolyte. Li-S battery can be considered as a liquid battery due to the dissolution of sulfur following electrochemical reduction, in which the electrolyte is acting as a “catholyte”. While the Li-PS shuttling can be managed at low sulfur loadings, it is more difficult to do so at high sulfur loadings, which is essentially required to realize full potential of Li-S battery. The strategies to mitigate Li-PS shuttling include the trapping in the electrode, blocking from interlayers and introducing catalysts capable of converting Li-PS into Li2S. While these approaches led to improved capacity within the first few cycles, subsequent fast capacity decay was also observed. In this project, in order to address these above mentioned challenges and also to establish fundamental understanding on the interaction of Li-PS with electrode components, we are proposing to develop dual targeting approach using smart polymeric materials to mitigate Li-PS shuttling. Our approach is three fold; (1) the development of defect engineered polymers via in-situ sulfur mediated polymerization, in which the defects will constitute either soft organic cations to interact with sulfur anion or glycol chains/crown ethers to target Li ions. These defects will allow us to confine the Li-PS within the active material. Importantly, the in-situ synthesized polymers will have high conductivity, thus facilitating efficient conversion of Li-PS into the insoluble Li2S due to the proximity of Li-PS to the conducting backbone. (2) We will explore catalytically active coating materials on the separator, which will act as a “smart filter” to recognize Li-PS and readily convert to insoluble Li2S. (3) Finally, we will integrate first two approaches to realize dual-capture mechanism for Li-PS at the smart polymer cathode as well as by interlayer blocking in order to realize the high performance and long life Li-S battery. For every part of this project, we will carry out detailed in-situ and ex-situ analysis to understand the operating mechanism and probe the interaction of Li-PS. These findings will allow us to establish fundamental understating on the mechanism and thus establish design principles for further development of Li-S battery components.
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