Abstract
We report that hot stretching of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) can lead to a preferred orientation of PEO crystalline lamellae, thereby reducing the tortuosity of the ion-conduction pathway along the thickness direction of the SPE film, causing improved ionic conductivity. The hot stretching method is implemented by stretching SPE films above the melting point of PEO in an inert environment followed by crystallization at room temperature while maintaining the applied strain. The effect of hot stretching on the crystalline orientation, crystallinity, morphology, and ion transport in PEO with two types of salts, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium triflate (LiCF3SO3), is investigated in detail. Wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) show that the orientation of PEO crystalline lamellae induces the formation of a short ion-conduction pathway along the through-plane direction of the SPE films, leading to 1.4- to 3.5-fold enhancement in the through-plane ionic conductivity.
| Original language | English |
|---|---|
| Pages (from-to) | 595-602 |
| Number of pages | 8 |
| Journal | ACS Macro Letters |
| Volume | 11 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 19 2022 |
Funding
This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. WAXS/SAXS data were measured on the Xeuss 3 SAXS/WAXS instrument via the ORNL instrumentation pool, and parts of the data interpretation were made at the Center for Nanophase Materials Sciences (CNMS) and Neutron Scattering Division, both of which are U.S. Department of Energy, Office of Science User Facilities. Y.W. acknowledges support by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Early Career Research Program Award KC0402010, under contract DE-AC05-00OR22725.
