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This content will become publicly available on June 18, 2019

Title: Mechanically Robust, Sodium-Ion Conducting Membranes for Nonaqueous Redox Flow Batteries

Sodium-based batteries are promising for grid-storage applications because of significantly lower cost compared to lithium-based systems. The advancement of solid-state and redox-flow sodium-ion batteries requires sodium-ion exchange membranes with high conductivity, electrochemical stability, and mechanical robustness. This study demonstrates that membranes based on poly(ethylene oxide) (PEO) can meet these requirements. Membranes plasticized with tetraethylene glycol dimethyl ether (TEGDME) achieve high ionic conductivity. Plasticized PEO membranes containing sodium triflate salt (NaTFS) show about 2 orders of magnitude higher conductivity compared to nonplasticized PEO membranes. Results from vibrational spectroscopy and differential scanning calorimetry describe the coordination chemistry in these multiphase materials and explain the mechanisms behind the increased conductivity. The mechanical properties of the membranes improve by addition of 5 wt % sodium carboxymethyl cellulose (CMC) without compromising the conductivity or electrochemical stability against sodium metal. In conclusion, the optimized membrane is an excellent candidate for low-cost energy storage systems that operate over a wide voltage window near ambient temperature.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [1] ;  [3] ;  [2] ; ORCiD logo [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  3. Nanomechanics, Inc., Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Volume: 3; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Electricity Delivery and Energy Reliability (OE)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; sodium-ion battery; membrane; poly(ethylene oxide); Raman; FTIR; conductivity; DSC; nanoindentation
OSTI Identifier:
1459302