Cross-Linked Electrospun Poly(ethylene oxide) Fiber Mats as Structured Polymer-Gel Electrolytes

Abstract

Poly(ethylene oxide) (PEO) containing pentaerythritol triacrylate (PETA) was electrospun to yield fiber mats that were subsequently crosslinked by exposure to UV irradiation. These mats were then supplemented with lithium perchlorate and swollen with ethylene/dimethyl carbonates to generate a structured polymer-gel electrolyte for Li-polymer battery applications. The fibrous mats were found to be composed of a nonwoven collection of ca. 1μm diameter PEO fibers with up to 85% porosity. Following UV exposure, the mats were rendered insoluble by chemical crosslinking, yielding gel fractions in excess of 80%. Upon incorporation of a liquid lithium ion electrolyte, the swollen mats were shown to maintain the fiberous framework and exhibit conductivities as high as 1.2 × 10-2 S/cm at room temperature. In contrast, a control mat of electrospun poly(vinylidene fluoride) containing fibers of comparable dimensions and identical electrolyte loading was found to yield a conductivity of only 5 × 10-3 S/cm.

Multiscale Lithium and Counterion Transport in an Electrospun Polymer-Gel Electrolyte

“…44 We note that there is no observable change in the local ion solvation structure due to the presence of or variations in the fiber mat. Notably, we do not see the shielding effect of the carbonyl oxygen atoms with addition of 1 M salt as observed by Bogle et al This indicates a difference in ion− solvent and/or ion−ion associations between solutions of these two anions (PF 6 − and OTf − ). Finally, we see little change in chemical shift and line width for the ether oxygen atoms in PEO10, PEO20, and PEO30 (Table SI-2) when compared to the pure 1 M LiOTf solution 17 O spectrum, further supporting no change to molecular-scale interactions when the liquid electrolyte is swollen into the fiber mat.…”

“…None of the measurements in this paper, including conductivity, will depend on changes in the dielectric permittivity of PEO, as there is no crystallinity present in any of the swollen membranes. 6 We note that a range of lithium salts and polar electrolyte solvents could be imbibed into this fibrous network to form highly conductive and mechanically robust gel electrolytes.…”

“…We utilize electrospinning from PEO/PETA solutions in conjunction with UV-initiated cross-linking. 6 After UV exposure (1 h per side) and vacuum drying, a mat composed of 1 μm diameter fibers swells and retains up to 1700 wt % of the liquid electrolyte ( Figure 1). Dynamic mechanical analysis (DMA) shows the bulk dry fiber mats have a Young's modulus of ∼5 MPa (Figure SI-1), which is likely much lower than the individual fiber modulus.…”

“…Thus, the length scale ac impedance probes should be considered in order to properly correlate changes in σ values to changes in material morphology. We can estimate (or predict) the electrophoretic mobility μ pred using 13,41 μ = D ZF RT pred meas (6) where D meas is the measured diffusion coefficient, Z is the number of unit charges per ion, F is Faraday's constant, and R is the universal gas constant. For this system, we calculate μ pred values of ∼6 × 10 −9 m 2 s −1 V −1 for lithium and triflate ions.…”

UV-initiated crosslinking of electrospun chitosan/poly(ethylene oxide) nanofibers doped with ZnO-nanoparticles: development of antibacterial nanofibrous hydrogel

“…[ 14 ] Forbey et al crosslinked PEO using PETA to generate a structured polymer–gel electrolyte for Li-polymer battery applications; they found that gel fraction and porosity data indicate that PETA is an effective crosslinking agent for the PEO mats, yielding gel fractions higher than 80%. [ 15 ]…”