Designing conductive pyrrolidinium-based dual network gel electrolytes : tailoring performance with dynamic and covalent crosslinking

Abstract

Transitioning toward a carbon-negative direction necessitates continued development and enhancement of existing lithium battery technologies. A key impediment for these technologies is the utilization of flammable organic solvent-based electrolytes, which pose significant safety risks. Furthermore, the recyclability of batteries has not reached the level required for transitioning to a circular economy. Here, poly(ionic liquid)-based dual network gel electrolytes are reported as safer and sustainable alternative materials. The materials employ both, dynamic (up to 45 mol%) and covalent crosslinking (up to 10 mol%), allowing the fabrication of mechanically stable gels with a high content (up to 65 wt%) of ionic liquid/salt both via thermal and photo polymerization. The dual nature of this network in interplay with other key components is systematically investigated. Mechanical stability (up to 0.7 MPa), combined with enhanced ionic conductivity (surpassing 10−4 S cm−1 at room temperature) is achieved via the synergetic combination of dynamic non-covalent and covalent crosslinking, resulting in improved electrochemical (up to 5 V) and thermal stability (reaching 300 °C) by the embedded ionic liquid. Moreover the presence of the dynamic crosslinks facilitates reprocessing at 70 °C without comrpomising the electrochemical performance, thus reaching full recyclability and reusability.