Fire-retardant solid polymer electrolyte films prepared from oxetane derivative with dimethyl phosphate ester group

Fire-retardant polymer electrolytes are key materials for safer operation of lithium secondary batteries and other large-size batteries than the batteries with organic liquid electrolyte. Solid polymer electrolyte systems with fire-retardant polymer matrixes have been investigated in only few cases. We prepare an oxetane derivative with dimethyl phosphate ester group (DPOX). The cross-linked poly(oxetane) matrixes for solid polymer electrolytes are prepared from DPOX and oxetane-based cross-linker (DDOE). DDOE has two oxetane rings at both of the ends of oligo-ethylene oxide chain. Conductivities in the range of 10−5 S cm−1 have been obtained for self-extinguishing, ion-conductive cross-linked poly(oxetane) matrix with DPOX and DDOE monomers. Polarization behavior of a lithium electrode in the cross-linked poly(oxetane)-based electrolyte films is also investigated. The polarization curves show some hysteresis character with potential steps, however, deposition and stripping of lithium on the lithium electrode are observed.

► New ion-conductive films prepared from oxetane derivative with dimethyl phosphate. ► Fire-retardant and self-extinguishable poly(oxetane)-based electrolyte films. ► Maximum conductivity of the electrolyte films with LiTFSI is 0.122 mS cm−1 at 353 K. ► Deposition and stripping of lithium in the electrolyte films observed.