Σεμινάριο τμήματος - Σειρά Διαλέξεων Μανώλης Γλυνός #2η μέρα

Περίληψη

Secondary batteries based on lithium metal anodes are the most sought-after candidates for next-generation storage systems since they can store a large amount of energy per unit mass or volume. However, unstable electrodeposition and uncontrolled interfacial reactions occurring in conventional liquid electrolytes cause unsatisfying cell performance and major safety concerns. Solid polymer electrolytes (SPEs) could be a “real game-changer” as they hold the promise to solve most of the problems of liquid electrolytes. SPEs are inherently safe, nonflammable, and compatible with lithium metal anodes.

Despite the considerable research effort in SPEs, the primary challenge is the development of solid materials with good mechanical properties without sacrificing ionic-conductivity. This talk will provide evidence that the use of complex macromolecular architectures holds the promise for the development of nanostructured materials with precise/desired morphologies that promotes SPEs properties to levels and temperature range not accessible before by conventional linear macromolecular systems. In particular, we will discuss the use of two difference polymer nanostructured nanoparticles, composed of high functionality star-shaped polymers, as additives to liquid electrolytes for the synthesis of SPEs that exhibit an unprecedented combination of high modulus and ionic conductivity [1,2]. In the first, when stiff/rigid polymer poly(methyl methacrylate), PMMA, nanoparticles, composed of high functionality star-shaped PMMA molecules, were incorporated to a liquid, ion-conducting, poly(ethylene oxide), PEO, doped with bis(trifluoromethane) sulfonamide (LiTFSI), the resulted SPEs exhibit two orders of magnitude higher conductivity and one order of magnitude higher mechanical strength compared to their linear PMMA blend analogues [1]. Key to this phenomenon is formation of highly interconnected, pure of liquid PEO, conducting regions as the result of PMMA nanoparticle dispersion within the liquid electrolyte. In the second, mikto-arm star copolymers composed of ion-conducting PEO arms that complement stiff insulating polystyrene arms, PS, were introduced to liquid PEO electrolytes and the resulted SPEs possess a shear modulus of G’ ~ 0.1 GPa and an ion conductivity σ ~ 10^-4 S/cm [2]. Noticeably, these SPEs show a strong decoupling between the mechanical behavior and ionic-conductivity. Molecular Dynamics simulations revealed that these particles constitute the first example of all-polymer amphiphilic nanostructured particles that their size, morphology, and phase dimensions may be precisely controlled via the selection of their macromolecular characteristics [3]. Due to their nanostructured morphology, these nanoparticles empower specific interactions with the liquid electrolyte, directing their self-assembly behavior into highly interconnected structures, promoting the decoupling of the antagonistic properties of conductivity and mechanical strength [2, 4]. As the synthesis of mechanical robust electrolytes with superior ion-conductivity has been the subject in a wide variety of solid-state electrochemical devices, this approach may significantly contribute to other applications, beyond lithium metal batteries, such as anion exchange membranes for fuel cells, efficient active layers in dye-sensitized solar cells, electrochromic devices and water desalination systems.

[1] E. Glynos, P. Petropoulou, E. Mygiakis, A. D Nega, W. Pan, L. Papoutsakis, E. P Giannelis, G. Sakellariou, S. H. Anastasiadis; Macromolecules 2018, 51, 2542. 

[12] E. Glynos, L. Papoutsakis, W. Pan, E. P Giannelis, A. D Nega, E. Mygiakis, G. Sakellariou, S. H. Anastasiadis; Macromolecules 2017, 50, 4699. 

[3] P. Bacova, E. Glynos, S. H. Anastasiadis, V. Harmandaris;  ACS Nano 2019, 13, 2439. 

[4] P. Bacova, F. Romanos, E. Glynos, A. N. Rissanou,  S. H. Anastasiadis, V. Harmandaris;  Soft Matter 2018, 14, 9562. 

Σύντομο Βιογραφικό Ομιλητή

Dr Emmanouil Glynos is a Research Scientist at the Institute of the Electronic Structure and Laser (IESL) of the Foundation for Research and Technology-Hellas (FORTH). He received his Bachelor in Physics from the University of Patras in 2003 and a PhD in 2007 in Materials Science in the core subject of Polymer Physics from the University of Edinburgh. After graduation, he joined as a postdoctoral research fellow the University of Michigan, working on the effect of macromolecular architecture on the physical properties of polymers at surfaces and interfaces. In 2012 he was appointed as a Research Investigator at the University of Michigan at the Center for Solar and Thermal Energy Conversion were his research focused in addressing important scientific challenges associated with the structure-property relation of organic photovoltaics and the correlation of the polymer active layers morphology to the overall performance of these systems. From 2017 to 2018, he was a Stavros Niarchos Research Fellow at FORTH/IESL in 2017-2018. The main objective of his current research at IESL/FORTH is to develop a fundamental understanding of, and controlling via macromolecular engineering, the structure and properties of nanostructured soft-materials that can be used as solid electrolytes in lithium-metal batteries and electrochromic devices, and as active layers in organic photovoltaics.