New oligoether plasticizers for poly(ethylene oxide)-based solid polymer electrolytes

• Published in: Ionics 2019-04, Vol.25 (4), p.1633-1643
• Main Authors: Ma, Qiang, Chakrabarti, Amartya, Mei, Xinyi, Yue, Zheng, Dunya, Hamza, Filler, Robert, Mandal, Braja K.
• Format: Article
• Language: English
• Subjects: Chemical analysis; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Electrolytes; Energy Storage; Ethylene oxide; High temperature; Ion currents; Lithium; Molten salt electrolytes; NMR; Nuclear magnetic resonance; Optical and Electronic Materials; Organic chemistry; Original Paper; Plasticizers; Polymers; Renewable and Green Energy; Solid electrolytes; Sulfonamides; Thermodynamic properties
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-018-2752-7

Two new plasticizers, nitrile groups terminated oligoether (NOE) and lithium sulfonamide groups containing oligoether (LSA), have been synthesized to construct superior poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs). The chemical structures of these plasticizers were confirmed by FTIR, 1 H-NMR, and elemental analysis. The electrochemical and thermal properties of the resulting SPEs have been thoroughly evaluated. The SPEs containing varied weight ratios of these plasticizers along with different Li/O mole ratios of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) have been investigated to optimize the electrolyte systems. Both plasticizers displayed good ionic conductivity at elevated temperatures. The SPE containing 40 wt.% of NOE in 12:1 PEO-LiTFSI complex showed ionic conductivity of 1.11 × 10 −4  S cm −1 at 312 K, while the SPE containing 10 wt.% of LSA in 12:1 PEO-LiTFSI complex showed 5.08 × 10 −5  S cm −1 and 1.88 × 10 −4  S cm −1 at room temperature and 312 K, respectively. Most notably, the SPE containing 10 wt.% LSA in 14:1 PEO-LiTFSI complex displayed ionic conductivity of 1.01 × 10 −3  S cm −1 at 343 K. Moreover, these SPEs exhibited good electrochemical stability (~ 4.2 V vs. Li + /Li) and displayed no noticeable thermal degradations below 350 °C.