Influence of N-doped TiO2 on lithium ion conductivity of porous polymeric electrolyte membrane containing LiClO4

Polymer electrolyte composites (PECs) based on poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) that contained lithium perchlorate (LiClO4) were prepared. N-doped TiO2 (N-Ti) was used as a filler to enhance the Li+ ion conductivity. Structural modification and electrochemical properties of the PECs were investigated in order to understand the effect of N–Ti in the polymer matrix on ionic conductivity. The PECs prepared with different N–Ti contents were characterized by SEM, mapping, DSC, and a.c. impedance. From the results, the prepared N–Ti-filled PECs showed a good ability to absorb and retain the Li+ ion. The presence of N–Ti in PVDF-HFP was resulted in increasing the ion conductivity significantly. The highest ion conductivity (6.7 × 10− 4 S/cm) was observed at a relative low N–Ti content (2.5 wt.%). It is believed that the addition of N–Ti could provide the foundation for the ionic transportation and ion-mobility of the PECs and the N-doping on TiO2 led to a more enhanced ionic conductivity by higher interaction between polar groups, such as O and N of N–Ti and Li+ ions.

Research highlights
► N-doped TiO2 was used as a filler of polymer electrolyte composites (PECs).
► The effect of N–TiO2 on electrochemical properties of PECs was investigated.
► From the results, PECs showed higher ionic conductivity with N–TiO2 compared to TiO2.
► It was due to strong interaction between nitrogen group of N–TiO2 and lithium ion.