Exploring low temperature Li~+ ion conducting plastic battery electrolyte

摘要

We report blend-based plastic polymer electrolyte (i.e., polyethylene oxide (PEO)-polydimethyl siloxane (PDMS)-lithium hexafluorophosphate (LiPFs)) with substantial improvement in DC conductivity at ambient and subambient temperatures when compared with literature reports. Conductivity variation with salt concentration, investigated within ±30 °C range, indicates an optimum conductivity of 5.6 x 10~(-5) S cm~(-1) at 30 °C for O/Li ～10 with a further lowering by one order at 0 °C and it remains unaltered at -10 °C. Enhanced conductivity in this blend electrolyte, though lower than two copolymer counterparts, is attributed to very low glass transition temperatures of the host polymers. X-ray diffraction (XRD) and scanning electron microscopy (SEM) suggest an effective blending between the two polymers with an effective interaction between the Li salt and the blend polymer matrix. Raman spectroscopy results indicated that cation (Li~+) coordination occurs at the C=0 site in PEO out of the two electron-rich sites (i.e., CO and Si-O-Si) in the PEO-PDMS blend. The blend electrolytes are predominantly ionic (t_(ion) ~97 %).