Rechargeable lithium-ion batteries are used in most portable electronic devices and in electric vehicles, which are considered the future of transport. Conventional liquid electrolytes used in such batteries pose safety concerns due to their high volatility, flammability, and toxicity. Solid-state polymer electrolytes (SSPE) can be considered a cheap, scalable and safe solution for the future generation of solid-state rechargeable batteries. Functionalized polysiloxanes allow the exploration of structure-property relationships, side group design, and thermal and dielectric properties, resulting in one of the highest permittivity for a polymer with a glass transition below room temperature. [1] This work investigates the synthesis and characterization of Li-ion conductive polysiloxane-based polymers grafted with different polar groups and concentrations in battery electrolytes (Figure 1). This allowed us to identify several promising polymers that, upon addition of a lithium salt and crosslinking, yielded flexible, mechanically and electrochemically stable SSPE. The obtained modified polymers exhibit ionic conductivities up to 0.375 mS cm^-1 at 60 °C, Li-ion transference number of 0.73, which is one of the highest reported for polymer electrolytes, electrochemical stability up to 5 V towards Lithium metal and stable charge/discharge cycles of symmetric cells over 1500 h. [2] The main advantage is the replacement of PVDF in cathode materials with our modified poylmers to obtain fluorine-free binder material with excellend adhesion to the electrolyte.

[1] Y. Sheima, Y. Yuts, H. Frauenrath, D.M. Opris, Macromolecules, 2021, 54, 5737–5749.

[2] F. Okur, Y. Sheima, C. Zimmerli, H. Zhang, P. Helbling, A. Fäh, I. Mihail, J. Tschudin, D. M. Opris, M. Kovalenko, K. Kravchyk, ChemSusChem, 2024, 17.