Auvergne-Rhône-Alpes, France
Date Posted
23 Apr 2024

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PhD Project

PhD Position (Université Grenoble Alpes (UGA), Grenoble, France) “Self-organized single-ion precise electrolytes: Towards efficient directional ionic transport”

Auvergne-Rhône-Alpes, France
23 Apr 2024

NOTE: this position listing has expired and may no longer be relevant!

Position Description

Materials Chemistry, Materials Science, Energy

UMR5819-SyMMES (CEA/CNRS/Univ. Grenoble Alpes), Systèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé
Host institution:
UGA: Université Grenoble Alpes
CNRS: Centre National de la Recherche scientifique/French National Center for Scientific Research
Doctoral school:
IMEP2: Engineering – Materials – Environment – Energetics – Procedures – Production – ED N°510
Annual tuition fee: 400 € / year

Through enabling the hierarchical self-assembly of ionic liquid crystals up to the meso/micro-scopic scale though ac-electric field-directed long-range organisation, the cutting-edge proposed project aims to go beyond the state-of-the-art level of ionic transport performances through a better understanding of the multiscale structure/transport interplay, notably by directing the self-assembly of long-range ordered nanoscale ionic pathways. The innovative strategy of defect management in functional materials, which plays crucial roles in many areas (e.g. doping in nanoelectronics) of nano-science/technology, is applied here in to directional confined ionic transport (nanoionics) to fulfil the pressing scientific challenge of lab-to-fab technology transfer towards electrolytes 2.0 for next generation electrochemical energy generation (e.g. DSSC) & storage (e.g.battery) solutions.

Research Topic:
Solid Polymer Electrolytes (SPEs) with high ionic conductivity and appropriate mechanical properties are envisioned as alternatives to liquid electrolytes for a safer generation of high performance electrochemical energy storage devices. Towards this goal, intensive research efforts onto new generations of SPEs have flourished worldwide since the first suggestion in the late 70s by Dr. M. Armand and co-workers. Yet, simultaneously achieving a full control of mechanical properties towards the desired level together with fast ionic transport still remains to date a red-brick wall; preventing the advent of a competitive SPE-based solution for electrochemical energy devices. Within the different material strategies developed to date, such as PEO-based homo and block copolymer anionic or cationic salts, single-ion polymer electrolytes (SIPEs) and polymeric ionic liquids (PILs) to name a few, SIPEs hold promises owing to their tunable by design material aspect (allowing the encoding of specific morphologies and physicochemical properties inherited from their precisely defined macromolecular architectures) coupled with its single ion (e.g. lithium for secondary lithium-ion battery or hydronium for fuel cell) transport capability. Using a series of single-ion precise copolymer electrolytes (SIPRECE) within which ionic functions will be precisely positioned onto a polymeric backbone ensuring the appropriate properties of ion conduction and multiscale organization, we will perform in depth structure/property correlation studies to evaluate the performances of this new type of SPEs. Multi-scale variable-temperature and relative humidity (when appropriate) WAXS/SAXS characterizations will be performed to determine the hierarchical self-organization of SIPRECE model systems across nano->meso->microscopic length scales. In-plane and through-plane ionic conductivity studies will be also conducted on a customized platform combining Electrochemical Impedance Spectroscopy (EIS), Polarized Optical Microscopy (POM), without or with electric field alignment, with the goal to assess the presence or absence of grain boundaries onto the measured ionic conductivity levels of non vs. fully-aligned SIPRECE model systems.

Thesis overview:
Precisely Functionalized Polymer Electrolytes[1]PFPEs, (all covalent vs supramolecular polyethylenes (PE)-based or supramolecular PFPEs) are new classes of materials displaying protic or ionic transport, which offer great promise for applications in low-cost, future energy-device applications. We aim to perform in situ studied polymer thin films with (w) and without (w/o) the application of an ac-electric field when confined into the micrometer gap (ca. 5-10 microns) defined by electrodes. This ac-field is a means to overcome the disorder present in melt-processed films, through alignment of the polymer chains. While it is well-established that multiscale (dis)order dramatically impacts the efficiency of proton/ion transport through and across state of the art (e.g. Nafion®[3] & PEO/Li salts[4-6]) conducting membranes, a clear structure/property correlation within the advanced and recently synthesized single-ion precisely functionalized polymers[1] remains elusive till date.

To end this unfavorable situation, Firstly we will follow the crystallization[2] of melted-processed thin films infiltrated and confined within two types of liquid crystalline (LC) cells to precisely reveal the complexity of their multi-scale structural organization (nucleation growth, crystallite size, grain boundaries (GBs)) in absence of an ac-electric field. Secondly and under the application of transverse vs. longitudinal ac-electric fields applied during their melt-processing, the same kinetic study will be conducted. The use of two types of LC cells will allow for the in situ variable temperature measurements of through-plane vs. in-plane proton (supramolecular PFPEs) and ion (ionically conducting PFPEs[7]) conductivity of unaligned vs. well-aligned thin films. This straightforward yet elegant approach will allow for an unprecedented clarification of the role of GBs and crystallite orientation (mosaicity) in their disorder-penalized vs. ultimately defect-free intrinsic level of protic and ionic conductivity[6,8]. The in situ experiments will allow us moreover to probe anisotropic protic/ionic transport[8] that should result from high quality layered conducting model systems. The melt-processing under ac-electric field will be optimized (strength, frequency, type of wave) to obtain the ultimate degree of alignment (disappearance of a GB-penalized thin film phase towards an ultimately defect-free single crystal) for maximizing the protic and ionic transport properties of the different polymer electrolytes under study in this project[1,6].

The large-scale implementation of future energy-storage technologies still awaits innovative breakthroughs in architectures of materials and devices. To go beyond the current state of the art performances of proton/ion conducting membranes (e.g. Nafion®[3] & PEO/Li salts[4-6]), considerable research efforts have been devoted to the design alternative materials. Yet, this has proved to be an extremely challenging task because the key property (conductivity) is typically improved at the expense of others (mechanical performances and (electro)chemical stabilities); mitigating the gain performance/effort balance. Recently, interest in semi-crystalline polymers for proton/ion conducting membranes has grown to address this issue; all covalent-based PFPE, as well as their supramolecular analogues, representing one of the most exquisite model systems to date[1,7,9]. The former are linear polymers with PE backbones and functional groups covalently bonded to the backbone at exactly regular intervals that are semi-crystalline at room temperature[3] while the latter are self-assembling supramolecular analogues with controlled low Mw PE sub-blocks ensuring mechanical integrity and where Ionic Functions (IFs) are localized at one or both extremities of di vs. triblock architectures (IF-PE or IF-PE-IF). Their nanophase segregated organization consists of layers of functional groups separated by crystalline alkyl domains, providing conducting materials with (continuous) 2D pathways for (efficient) proton/ion conduction. This unfavorable situation is precluding further discussion on their effective (in presence of disorder) vs. intrinsic (in absence of disorder) and ultimate performances in terms of proton or ion conductivity. To go a major step further, this subject aims at addressing these key questions through simple yet powerful set of carefully designed experiments, combining advanced XRD[2], ac-electric field alignment and Electrochemical Impedance Spectroscopy (EIS) under “a few micron thick” conducting membranes confined within LC cells.

Research Methodology:
A multimodal experimental approach coupling complementary techniques (Polarized Optical Microscopy (POM), scattering techniques, NMR, impedance/dielectric spectroscopy) will be applied to correlate structures and transport properties across all relevant length scales. The main goal is to perform thorough characterizations of this generic family of advanced solid electrolytes aiming at surpassing the current scientific and technological hurdles that limit the practical (scale-up) implementation of existing technologies into numerous applications (e.g. ion transport, water filtration or molecular separation). The large variety of available synthons mastered by researchers of the UMR5819-SyMMES lab will help to generate generic families to evaluate and optimize the scope and performance of single-ion solid electrolytes. A dedicated multimodal platform already implemented at the UMR5819-SyMMES (CEA/CNRS/UGA) lab since 2016 thanks to the CNRS funding of the exploratory instrumental project PLEO for which the thesis Advisor is the PI, will be used during this PhD work. This platform works in the direct space (POM) and gives access to the carrier dynamic through impedance/dielectric spectroscopy (over the 1mHz-50 MHz frequency range) while simultaneously opening the possibility of applying an ac-electric field. The actual challenge set is to additionally acquire structural information in the reciprocal space using (GI)WAXS/SAXS ((Grazing Incidence) Small- and Wide X-ray Angle Scattering). This platform allows also the determination of both the ionic conductivity and structural organization in the in-plane vs. through-plane configurations, to reveal potential anisotropic features.

Skills required:
1) Organic Chemistry: (Multi-Step) synthesis and purification of functional materials 2) Electrochemistry of electrolytes (dielectric/impedance spectroscopy, electrochemical characterisations) 3) X-Ray scatterings (SAXS/WAXS) 4) Soft Matter knowledge (polymer, gel, liquid crystals)

[1] L. Santonja-Blasco et al., Adv. Polym. Sci. 276 133-182 (2017) [2] G. Portale et al., Adv. Polym. Sci. 277 127-166 (2017) [3] G. He et al., Adv. Mater 27, 5280-5295 (2015). [4] D.T. Hallinan & N.P. Balsara, Annu. Rev. Mater. Res. 43, 503-525 (2013). [5] Z. Xue et al., J. Mater. Chem. A 3 19218-19253 (2015). [6] D. Golodnitsky et al., J. Electrochem. Soc. 162, A2551-A2566 (2015). [7] U.H. Choi et al., Macromolecules 48, 410−420 (2015). [8] S. Cheng et al. RSC Adv. 5, 48793-48810 (2015). [9] C.F. Buitrago et al., Macromolecules 46, 9003-9012 (2013)

1: Single-ion precise electrolytes
2: Ionic transport
3: Long-range organisation
4: Mosaicity
5: Structure/transport relationship
6: ac-electric field driven self-assembly

Level of French required: B1 (intermediate)
Level of English required: C2 (proficiency)
Opportunity to make your thesis in English

PhD Supervisors:
Dr. Patrice RANNOU

CNRS senior researcher, PhD/HDR
Dr. Patrice RANNOU
CNRS Director of Research, PhD/HDR

How to Apply

Dates: Application deadline: May 25, 2018 @ 6:00 pm (CET). Duration: 36 months Start date: October 1, 2018 Funding Offer: Funding type: Contrat Doctoral/PhD Fellowship Funding amount: 1450 € Net Salary / month Eligibility criteria: The PhD candidate should preferably hold a Master degree in Materials Science, Polymer Chemistry, or Polymer Physics dealing with functional soft matter, a previous experience in the synthesis and/or multiscale structure (SAXS/WAXD)/property (Ionic or electronic conductivity) correlations of functional (i.e. electronically/ionically conducting) materials being especially appreciated. A demonstrated ability to perform independent work, to work across borders of chemistry and physics of functional soft maters, and excellent communication and writing (English) skills are equally important criteria with respect to academic qualifications and scientific merit for the selection of the PhD candidate. The PhD position is immediately available Selection process: The deadline for application is May 25, 2018 @ 6:00 pm (CET). We encourage candidates to apply as soon as possible. The search for candidates will continue until the position is filled. Applicants should provide an e-application file combining a curriculum vitae, a letter of motivation, a summary of their research experience, and a list of publications. A single pdf should be addressed both to Dr. Manuel Marechal: & Dr. Patrice Rannou: The applicants should arrange that at least two reference letters are sent directly to the contact address above.