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Ion Conduction and Viscoelastic Response of Epoxy‐Based Solid Polymer Electrolytes Containing Solvating Plastic Crystal Plasticizer
Author(s) -
Jang Hye Kyeong,
Jung Byung Mun,
Choi U Hyeok,
Lee Sang Bok
Publication year - 2018
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201700514
Subject(s) - materials science , epoxy , diglycidyl ether , ionic conductivity , curing (chemistry) , plastic crystal , electrolyte , composite material , dynamic mechanical analysis , arrhenius equation , polymer chemistry , fourier transform infrared spectroscopy , polymer , chemical engineering , activation energy , chemistry , bisphenol a , organic chemistry , electrode , engineering , phase (matter)
To develop a safe electrolyte for lithium‐ion batteries, solid polymer electrolytes (SPEs) are prepared using a commercially available cross‐linkable diglycidyl ether of bisphenol‐A (DGEBA) epoxy resin, a methyl tetrahydrophthalic anhydride (MeTHPA) curing agent, and a plastic crystal‐based electrolyte containing a mixture of succinonitrile (SN) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) by a simple thermal curing process. For the uncured mixture of DGEBA/MeTHPA/SN/LiTFSI, oscillatory and steady shear measurements are conducted to investigate microstructure and processability; the storage modulus ( G ′) exceeds the loss modulus ( G ″) at all frequencies studied (solid‐like behavior) and the viscosity decreases with an increase in the shear rate (shear‐thinning behavior), demonstrating that there is a network structure, and the connected structure changes at high shear rates. Fourier transform infrared spectroscopy confirms the physical interactions between Li + of LiTFSI and anhydride group of MeTHPA, which are responsible for the network structure, and helps to rationalize the observed moduli and viscosity. For the cured epoxy‐based SPEs, their ionic conductivities follow the Arrhenius temperature dependence, and increasing SN/LiTFSI electrolyte content leads to higher conductivity and lower activation energy for conduction, resulting in ionic conductivity σ DC ≈ 2 × 10 −4 S cm −1 with a shear modulus approaching G ′ ≈ 1 MPa at room temperature.