Abstract
We have studied ion transport in electrolytes created by blending two different polymers and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The polymers covered in this study are poly(ethylene oxide) (PEO), poly(1,3,6-trioxocane) (P(2EO-MO)), and poly(1,3-dioxolane) (P(EO-MO)). Ion transport is quantified by the product κρ+which is defined as the efficacy of the electrolytes, where κ is conductivity and ρ+is the current fraction determined by the Bruce-Vincent method. Polymer blends can be either one-phase or macrophase-separated. We used small-angle neutron scattering (SANS) to distinguish between these two possibilities. The random phase approximation (RPA) was used to interpret SANS data from one-phase blends. The effect of added salt on polymer blend thermodynamics is quantified by an effective Flory-Huggins interaction parameter. All polymer blends were one-phase in the absence of salt. Adding salt in small concentrations results in macrophase separation in all cases. One-phase systems were observed in the PEO/P(EO-MO)/LiTFSI blends at high salt concentrations. In most of the polymer blend electrolytes, the measured κρ+was either lower than or comparable to that of the homopolymer electrolytes. An exception to this was one-phase PEO/P(EO-MO)/LiTFSI blends electrolytes at high salt concentrations.
| Original language | English |
|---|---|
| Pages (from-to) | 11023-11033 |
| Number of pages | 11 |
| Journal | Macromolecules |
| Volume | 55 |
| Issue number | 24 |
| DOIs | |
| State | Published - Dec 27 2022 |
Funding
This work was intellectually led by the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science, under Contract DE-AC02-06CH11357, which supported synthesis work conducted by C.K., R.L.S., and B.A.A. under the supervision of G.W.C. and characterization work conducted by J.L. and K.W.G. under the supervision of N.P.B. We acknowledge the Center for Neutron Science at the University of Delaware and funding under cooperative agreement #70NANB20H133 from NIST, U.S. Department of Commerce. This research used resources at the High Flux Isotope, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron facilities used in this work. K.W.G. acknowledges funding from a National Defense and Science Engineering Graduate Fellowship. The statements, findings, conclusions and recommendations are those of the authors and do not necessarily reflect the view of NIST or the U.S. Department of Commerce. Certain commercial equipment, instruments, suppliers and software are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.