Ionic conductivity and the correlation with viscosity in pectin ionic liquid electrolytes

Biopolymers have received considerable attention for their applications in battery electrolytes due to their low cost, easy processability, sustainability, and biodegradability. In this paper, we report the results of pectin-IL electrolytes consisting of pectin and an ionic liquid (IL) 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). We find that the Nearest-Einstein conductivity (σNE) decreases with pectin loading. On the other hand, the viscosity (η) increases with pectin loading, indicating the enhancement in the mechanical strength of the electrolyte. Remarkably, we observe an interesting power-law relationship between the σNE and η such that σNE~η−1.1, an observation that is slightly distinct from the pure IL electrolytes i.e., σNE~η−1. These results offer flexibility in controllably tuning the conductivity and mechanical strength of the IL electrolytes by judiciously choosing the amount of pectin polymer. © 2025 American Institute of Physics Inc.. All rights reserved.