In Situ Polymerized Electrolytes with Fully Cross-Linked Networks Boosting High Ionic Conductivity and Capacity Retention for Lithium Ion Batteries

Abstract

In this report, quasi-solid polymer electrolytes (QPEs) based on dicationic imidazolium-based poly(ionic liquid) (PIL) cross-linker end capped with polyethylene glycol (PEG) segments have been UV cured directly onto lithium anode via an in situ solventless strategy, creating a direct, effective, and versatile method for electrolyte production. Depending on the composition, room temperature ionic conductivities are found to vary between 0.7 and 1.1 mS cm −1 , while compressive elastic moduli reveal the values between 0.072 and 0.349 MPa observed at a 5% strain. These results, together with FT-IR analysis, indicate that fully cross-linked networks can be formed in the QPE-1:1.6 sample, which is conducive to generating well-connected ion channels and affords the assembled lithium ion batteries (LIBs) with a wide electrochemical window and a remarkable discharge capacity retention (153 mAh g −1 at 0.2 C and 133 mAh g −1 at 1 C) at 25 °C. Also, the adopted in situ polymerization can contribute to an enhanced electrolyte/electrode interfacial compatibility and conformal attachment, suppressing the growth of lithium dendrites and extending the cycle life of the assembled battery. Both the outstanding electrochemical properties of QPE-1:1.6 and the facile fabrication process potentially make it one of the promising electrolyte candidates for future LIBs developments.