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 . The increase of energy density necessary to promote this future revolution imposes to develop “new” chemistries for both the active electrode materials and electrolyte. 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 properties 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 ef fects like favored dendritic growth 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, laden with a lithium salt to the single-ion BCEs (SIEL) comprising grafted lithium trifluoromethanesulfonylimide (TFSILi) 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 t emperature will also be shown.

Contact : patrice.rannou@cea.fr