SINGLE-ION BLOCK COPOLYMERS FOR HIGH VOLTAGE LITHIUM METAL BATTERIES

Renaud Bouchet (renaud.bouchet@lepmi.grenoble-inp.fr), LEPMI, Grenoble INP

Funding: LABEX CEMAM

Industrial partner involved: Blue Solutions (Dr M. Deschamps)

Collaborating partners: LPS (Orsay, SAXS), CEA-LITEN (Grenoble, XPS, TEM-EELS)

Context:

We have recently designed an original functional polymeric architecture based on single-ion triblock copolymers BAB. These triblock copolymer Single-Ion ELectrolytes (SIELs), have a poly(ethylene oxide) (PEO) middle block and poly(styrene lithium trifluoromethanesulfonylimide) (PSTFSILi) outer blocks. They have shown outstanding performances in terms of conductivity (1.3 × 10^–5 S/cm at 60 °C), Li⁺ transference number (t⁺ > 0.85), mechanical properties (?_rupt = 10 MPa at 40 °C) and an unexpected enlarged electrochemical stability up to 5 V vs. Li⁺/Li[i]. This work opened a large avenue in the community for the development of new single-ion polymer electrolytes supported by a growing interest of the battery companies for solid state batteries as shown by the recent acquisition by Bosch of the SEEO Company where block copolymer electrolytes are developed. In practice, the interest is mainly du to the guaranty of safety, energy density, and low cost process of lithium metal polymer technology[ii]. Over the world, Blue Solutions Company is the leader of this technology. Among the fundamental questions that arise, the understanding of the relationships between the polymer chemistry, the polymer architecture and meso-structuration and the functional properties is still a need. Especially, the understanding of the extended electrochemical window (5V) of our recently developed single-ion is of first importance.

Project:

Our global objective aims at improving the performances of LMP batteries through long-term innovation in polymer chemistry and macromolecular architecture. This project proposes a fundamental study to address the very exciting results recently obtained with our SIELS. especially, the impact of the block chemistry on the resulting physical properties, especially the electrochemical stability at high potential.

Thus the work will be focus on tackling this interfacial stability by coupling several characterization tools to check the bulk morphology (SAXS, SANS), the transport properties (EIS, PFG-NMR) and the ionic interactions (anion-cation and ions-PEO) (Raman and IR spectroscopies). However, the main challenge will be to characterize the interface Active Materials/SIELs itself by means of 1/ electrochemical methods, especially electrochemical impedance spectroscopy (EIS), and almost 2/ TEM-EELS to analyse the interfaces composition on a thin slice (obtained by FIB-SEM or cryo-microtome) obtained on composite or model electrode. A part of the work will be done in collaboration with colleagues, experts of mesophase (SAXS, SANS) or surface chemistry analysis (XPS, TEM-EELS).

Note: Another post-doc funded by Blue Solutions will be hired. His job will be the formulation of composite electrodes with different active materials, the assembly and test of the different LMP batteries. Both postdocs will proceed in parallel with complementary skills and tasks.

Profile of the candidate: Competence in TEM as well as in sample preparation by FIB or by cryo-ultra microtome is highly desired. Knowledge on physicochemistry of polymer or on soft matter would be very appreciated. Knowledge in electrochemistry and on the electrochemical energy storage would be a plus, but not mandatory since this skill is one of the expertises of LEPMI and the candidate will benefit of that.

[1] R. Bouchet, A. Aboulaich, S. Maria, J-P Bonnet, L. Lienafa, T. N. T. Phan, D. Gigmes, D. Devaux, R. Denoyel, M. Armand, Nat. Mat., 12, 2013, 452–457

[1] Tarascon J. M., Armand, M.  Nature, 414, 2001, p.359