Abstract
Maximizing ion conduction in single-ion-conducting ionomers is essential for their application in energy-related technologies such as Li-ion batteries. Understanding the anion chemical composition impacts on ion conduction offers new perspectives to maximize ion transport, since the current approach of lowering Tg has apparently reached a limit (lowest Tg ∼ 190 K, highest conductivity ∼10−5-10−4 S cm−1). Here, a series of random ionomers are synthesized by copolymerizing poly(ethylene glycol)methacrylate with either sulfonylimide lithium methacrylate (MTLi) or sulfonate lithium methacrylate (MSLi) using reversible addition-fragmentation chain transfer (RAFT) polymerization. Li-Ion conduction and self-diffusion coefficients (DLi+) of the ionomers are characterized with dielectric relaxation spectroscopy (DRS) and pulsed-field-gradient (PFG) NMR diffusometry, respectively. Increasing ion content decreases the Li-ion conductivity and DLi+, as expected from the increased Tg. Moreover, a considerably lower ionic conductivity and DLi+ are observed for MSLi compared to MTLi at constant ion content and Tg/T. As revealed from X-ray scattering, strong ion aggregation in MSLi results in much lower conductivity and DLi+ compared with less aggregated MTLi based on the more delocalized sulfonylimide anion. These results emphasize the detrimental and molecularly specific role of ion aggregation in Li-ion conductivity, and highlight the necessity for minimizing ion aggregation via the rational choice of anion chemical composition.
Original language | English (US) |
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Pages (from-to) | 14569-14579 |
Number of pages | 11 |
Journal | Journal of Materials Chemistry C |
Volume | 10 |
Issue number | 39 |
DOIs | |
State | Published - Sep 2 2022 |
All Science Journal Classification (ASJC) codes
- General Chemistry
- Materials Chemistry