Titre : Block Copolymers as Efficient Electrolytes in Lithium Metal Batteries
Endroit : Pavillon J.-Armand Bombardier, salle 1035 à 11 h
Hôte : Michaël Dollé
Cette conférence sera prononcée (en anglais) par le Professeur Renaud Bouchet du laboratoire d'Électrochimie et de Physico-chimie des Matériaux et des Interfaces, Institut polytechnique de Grenoble.
Résumé:Today the environment is a major society concern and the polluting fossil energy consumption, more and more expensive, is a drag on our economy, thereby the development of alternative transportation such as electric or hybrid vehicles, has become a key need for a sustainable long term development[1]. The increase of energy density necessary to promote this future revolution imposes to develop “new” chemistries for both the active electrode materials and electrolyte[2],[3]. However, for large-scale applications a safety issue comes from the liquid electrolytes as they embedded organic solvents that can likely leak or generate flammable reactions. The use of a solid polymer electrolyte (SPE) could solve most of the safety issues encounter with liquid electrolyte. However, the development of SPE has been hampered by two hurdles i/ the inability to design a SPE that has both a high ionic conductivity and good mechanical properties3 and ii/ the motions of lithium ions carry only a small fraction of the overall ionic current which leads during battery operation to the formation of strong gradients of concentration with highly noxious effects like favored dendritic growth[4] and limited power performances.
In this context, we are developing nanostructured multifunctional block copolymer electrolytes (BCE), B-A-B comprising a central A block based on poly(ethylene oxide) (PEO) that brings ionic conductivity and a B block that brings other functionalities like mechanical properties, electrochemical stability, increase of transport number, etc… Our approach in improving the performance of BCEs starting from neutral BCEs like PS-POE-PS[5],[6],[7] laden with a lithium salt to the single-ion BCEs (SIEL) comprising grafted lithium trifluoromethanesulfonylimide (TFSILi)[8] on the B block, will be presented. Especially, the impact of the BCEs architecture- composition, chemistries of the PEO based block as well as of the B block, on the physical properties such as the morphology, the thermodynamic transitions, the mechanic stability and the ion transport will be discussed. At last, for a complete panorama, the results obtained with the best BCEs in battery prototypes with the aim of reducing the operation temperature will also be shown.
[1] J. Tollefson, Nature, 456, 2008, 436-440 [2] F. Cheng, J. Liang, Z. Tao, J. Chen, Advanced Materials, 23, 2011, 1695-1715 [3] M. Armand, J-M Tarascon, Nature, 451, 2008, 652-657 [4] J-N Chazalviel, Physical Review A, 42, 1990, 7355-7367 [5] E. Beaudoin, T. N. T. Phan, M. Robinet et al., Langmuir 2013, 29, 10874−10880 [6] R. Bouchet, T. N. T. Phan, E. Beaudoin et al., Macromolecules 2014, 47, PP2659-2665 [7] D. Devaux, D. Glé, T. N. T. Phan et al., Chem. Mat. 2015, 27, pp4682-4692 [8] R. Bouchet, A. Aboulaich, S. Maria et al. Nature Materials, 12, 2013, 452–457.
