Disulfide Metathesis-Assisted Lithium-Ion Conduction for PEO-Based Polymer Electrolytes

The disulfide metathesis is a promising candidate in the dynamically exchanged strategy for improving the self-healing ability of polymer electrolytes (PEs). However, the enhancement effects on the ionic conductivities of PEs are generally ignored while introducing a dynamic covalent bond to PEs. Herein, the oligo(ethylene oxide)-based additive containing a disulfide bond (S–S additive) was synthesized via Michael addition reaction of cystamine and poly(ethylene glycol) methyl ether acrylate (PEGA). Short PEG chains complexed with Li+ in a S–S additive migrated rapidly in PEs because of the dynamically exchanged strategy of the disulfide bond. Moreover, disulfide bonds in a S–S additive possessed the ability to exchange with the cross-linked network containing disulfide bonds (S–S net). The as-prepared PEs exhibited a high room temperature ionic conductivity of 1.24 × 10–4 S cm–1, demonstrating that the disulfide metathesis-assisted Li+ conduction was feasible for enhancing ionic conductivities of PEs. Relative to other PEO-based PEs, these disulfide-containing PEs possessed a high Li+ transference number (0.54). Furthermore, the lithium-metal batteries (LMBs) assembled with PEs in the presence of a S–S additive presented stable cycle performance, indicating the promising potential of these PEs as candidates for next-generation LMBs.