Ion conducting corn starch biopolymer electrolytes doped with ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

Biodegradable corn starch–lithium hexafluorophosphate (LiPF6) based biopolymer electrolytes were prepared by solution casting technique. Ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) was doped into the polymer matrix. Upon addition of 50 wt.% BmImPF6, the maximum ionic conductivity of (1.47 ± 0.02) × 10− 4 Scm− 1 was achieved due to its higher amorphous region. This result had been further proven in ATR-FTIR study. Frequency dependence of conductivity and dielectric studies reveal the occurrence of polarization at the electrolyte–electrode interface and thus form the electrical double layer, asserting the non-Debye characteristic of polymer electrolytes. This result is in good agreement with dielectric loss tangent study. Based on the changes in shift, changes in intensity, changes in shape and existence of some new peaks, attenuated total reflectance-Fourier Transform Infrared (ATR-FTIR) divulged the complexation between corn starch, LiPF6 and BmImPF6, as shown in the spectra.

► Ionic liquid BmImPF6 was doped into biodegradable corn starch. ► Maximum ionic conductivity of (1.47 ± 0.02) × 10− 4 Scm− 1 was achieved. ► ATR-FTIR divulged the complexation between corn starch, LiPF6 and BmImPF6.