Herein, we show that using a thin (~60 µm) gel prepared by electrolyte exchange of the ILE (1.0 M LiFSI in PYR14TFSI) in a PVDF-HFP IG with an LHCE (1.0 LiFSI: 1.2 DME: 3.0 TTE, by mole), results in a pseudo-solid state Li-FeF3 battery with high rate capability at room temperature (up to 1.0 mA cm -2 ) and stable cycling. Improved performance at room temperature is enabled by three key properties of the LHCE-filled gel. First, ionic conductivity (1.92 mS cm -1 at 25°C and 3.74 mS cm -1 at 60°C) is up to two orders of magnitude greater than previous solid state iron fluoride batteries (vide supra). Second, the unique solvent structure of the LHCE results in high CE (>98%) and stabilizes the chemical interface of the gel with both the anode and cathode. Third, the flexibility of the polymer gel enables adaptability to the significant volume expansion that occurs during the conversion reaction (up to 30%). Overall, the results obtained here have the potential to be broadly applicable to batteries employing conversion cathodes. Finally, although we focus on the LHCE-filled gel (due to its superior room temperature performance), we show promising preliminary results for the precursor IG at elevated temperature (60 °C).