Oligosiloxanes with Silatrane Moieties for Use in Lithium-ion Conductive Matrices

Solvent-free polymer electrolytes are critical for improving the performance of electrochemical devices. With the aim of developing a new silicon-based polymer electrolyte that does not contain poly(ethylene oxide) or ionic-liquid moieties, we present the synthesis, spectroscopic, thermogravimetric, and electrochemical characterization of a polymer combining flexible polysiloxanes with polar silatrane moieties at their chain ends or at their pendant chain ends prepared via hydrosilylation. The polymers obtained readily dissolve lithium bis (trifluoromethylsulfonyl)amide (LiTFSA), whereas lithium trifluoromethylsulfonate (LiOTf) and lithium bis(oxalato)borate (LiBOB) exhibit lower solubility. The polysiloxane with silatrane chain ends show an ionic conductivity of about 10 −6 S cm −1 at ambient temperature, a wide electrochemical stability of 5.4 V, a high lithium-ion transference number of 0.70, and good long-time thermal stability up to 150 °C. The pendant-type polymers show lower ionic conductivity because of their high glass transition temperature. Despite their low conductivity, the solvent-free polymer/LiTFSA complexes might find application as binder materials.