Cross-Linking of Sugar-Derived Polyethers and Boronic Acids for Renewable, Self-Healing, and Single-Ion Conducting Organogel Polymer Electrolytes

Abstract

This report describes the synthesis and characterization of organogels by reaction of a diol-containing polyether, derived from the sugar d-xylose, with 1,4-phenylenediboronic acid (PDBA). The cross-linked materials were analyzed by infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), scanning electron microscopy (FE-SEM), and rheology. The rheological material properties could be tuned: gel or viscoelastic behavior depended on the concentration of polymer, and mechanical stiffness increased with the amount of PDBA cross-linker. Organogels demonstrated self-healing capabilities and recovered their storage and loss moduli instantaneously after application and subsequent strain release. Lithiated organogels were synthesized through incorporation of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into the cross-linked matrix. These lithium-borate polymer gels showed a high ionic conductivity value of up to 3.71 × 10-3 S cm-1 at 25 °C, high lithium transference numbers (t+ = 0.88-0.92), and electrochemical stability (4.51 V). The gels were compatible with lithium-metal electrodes, showing stable polarization profiles in plating/stripping tests. This system provides a promising platform for the production of self-healing gel polymer electrolytes (GPEs) derived from renewable feedstocks for battery applications.