Polymer-supported ionic liquids (ionogels) are emergent, nonvolatile electrolytes for electrochemical energy storage applications. Here, chemical and physical interactions between the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI) and three different cross-linked polymer scaffolds with varying chemical functional groups have been investigated in ionogels fabricated via in situ UV-initiated radical polymerization of methyl methacrylate (MMA), 2,2,2-trifluoroethyl methacrylate (TFEMA), or 2-(dimethylamino)ethyl methacrylate (DMAEMA) and a small amount of the cross-linker pentaerythritol tetraacrylate. Experimental findings demonstrate that the chemical functionality of the polymer side groups can significantly affect the degree of ion dissociation within the ionic liquid component of the ionogel and that the fraction of dissociated ions is the dominant factor in determining relative ionic conductivity in these materials, rather than any large differences in ion diffusivity. The MMA-based polymer scaffold exhibits a stronger attractive interaction with EMI TFSI (as evidenced by a higher activation energy of ionic conductivity) compared to the TFEMA- and DMAEMA-based scaffolds, resulting in consistently lower ionic conductivity values for MMA-based ionogels. These results may offer guidance toward the rational selection of future polymer-ionic liquid pairings in order to maximize the fraction of dissociated ions, thereby yielding highly conductive ionogel electrolytes.

Pressurization of solid oxide cells improves performance by reducing electrode polarization resistance (R P ) and facilitates system integration with balance of plant components such as pressurized storage tanks. However, there are few reports on pressurization effects for electrodes designed for low-temperature operation and utilizing infiltrated catalysts. Here we report an electrochemical impedance spectroscopy study of high performing oxygen electrode materials, SrTi0.3Fe0.63Co0.07O3-∂ (STFC) and PrOx infiltrated STFC, for oxygen partial pressures ( ) from 0.1 to 8 atm and temperatures from 550 to 650 °C. decreases more with pressurization for STFC:PrOx, fitting well to with an exponent n∼0.3, compared to n∼0.25 for STFC. The combination of PrOx infiltration and pressurization yields a substantial R P decrease, e.g., at 600 °C by ∼7 times from 0.36 Ω cm2 at = 0.2 atm for STFC to 0.055 Ω cm2 at = 4 atm for STFC:PrOx. A transmission-line-based circuit model impedance fit reveals that the significant oxygen surface reaction (Rsurf) resistance contribution decreases substantially with PrOx infiltration; and its dependence become more pronounced, with n increasing from ∼0.25 to ∼0.5. Rsurf for STFC:PrOx decreases so much at elevated that the electrode/electrolyte interface resistance dominates.

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