High energy density batteries are needed to meet ever expanding energy demands. Li metal batteries (LMBs) containing conversion cathode materials are a promising route for achieving this goal due to large working voltages, 1, 2 multi-electron reactions, and the exceptional theoretical capacity of Li metal (3860 mAh g -1 ). For example, the three-electron reaction that FeF3 undergoes with Li, paired with a 2.7 V Li-FeF3 potential difference, 2 confers a theoretical energy density of 1922 Wh kg -1 . High energy density, along with environmental benignity and rich natural abundance, has spurred interest in FeF3 as an LMB cathode material. Despite these advantages, Li metal introduces safety concerns (e.g., flammability, side reactions, and dendrites) that are exacerbated by liquid electrolytes. Accordingly, there has been a push towards solid state batteries. The biggest challenges encountered with solid state batteries are low ionic conductivities, difficulty forming intimate low resistance interfaces with microporous electrodes, and mechanical instability introduced by electrode volumetric changes. An innovative way to address these detriments is to use a pseudosolid state ionogel (IG) separator. IGs consist of an ionic liquid electrolyte (ILE) encapsulated by a solid matrix. The coexistence of solid and liquid phases combines the mechanical properties of a solid (e.g., structural support and elasticity) with the physical properties of a liquid electrolyte (vide infra). ILEs have high ionic conductivities and are stable over a broad range of temperatures, chemical environments, and voltages. Additionally, ILEs are nonflammable and can thus improve the safety of LMBs. When an IG is deposited onto a cathode, the low volatility of the ILE assists in forming a gel that penetrates the pores of the cathode. In turn, this provides a localized electrolyte reservoir that decreases interfacial resistance relative to pure solid-state electrolytes. We recently reported a procedure for exchanging the ILE in an IG (through a series of passive diffusion steps) with a less viscous electrolyte. This procedure can be used to impart the gel with more desirable properties (e.g., lower charge transfer resistance and higher conductivity). In the present report, exchange of the ILE in a flexible, polymer IG with a localized high concentration electrolyte (LHCE; vide infra) imbues high ionic conductivity, high coulombic efficiency (CE), and stability with both electrodes (cathode and anode), while preserving pore interpenetration from the original IG. The latter property represents a marked advantage relative to freestanding polymer gels prepared by swelling, as it leads to the formation of intimate and mechanically compliant electrode/electrolyte interfaces.