Modifying Ionogel Solid-Electrolytes for Complex Electrochemical Systems

The solution processability of ionogel solid electrolytes have recently garnered interest in the Li-ion battery community as a means to address the interface and fabrication issues commonly associated with most solid-electrolytes. However, the trapped ionic liquid (ILE) component has hindered the electrochemical performance. Herein, we present a process to tune the properties by replacing the ILE in a silica-based ionogel after fabrication with a liquid component befitting the desired application. Electrochemical cycling under various conditions showcases gels containing different liquid components incorporated into LiFePO4 (LFP)/gel/Li cells: high power (455 W kg-1) systems using carbonates, low temperature (-40 oC) using ethers, or high temperature (100 oC) using ionic liquids. Fabrication of additive manufactured (AM) cells utilizing the exchanged carbonate-based system is demonstrated in a planar LFP/Li4Ti5O12 (LTO) system, where a marked improvement over an ionogel is found in terms of rate capability, capacity, and cycle stability (118 vs 41 mAh g-1 at C/4). This process represents a promising route to create a separator-less cell, potentially in complex architectures, where the electrolyte properties can be facilely tuned to meet the required conditions for a wide range of battery chemistries while maintaining uniform electrolyte access throughout cast electrodes.