Patternable, Solution-Processed Ionogels for Thin-Film Lithium-Ion Electrolytes

lonogels have recently attracted attention as pseudo-solid-state electrolytes based on their ability to confine an ionic liquid electrolyte within the mesoporous network of a sol-gel-derived inorganic matrix. Herein we report on the development of two important capabilities for ionogels. In one case, we incorporated spin-coated, 600-nm Li+-conducting ionogel films in electrochemical cells of LiFePO4/ionogel/Li. A key feature in this work is the ability to have the sol thoroughly penetrate the LiFePO4 electrode prior to gelation. Devices operating at C/2 achieved capacities of 125 mAh/g for some 150 cycles with minimal capacity loss. In the second case, we developed a UV crosslinking synthesis method and demonstrated photo-patterning of the ionogel. The realization of a photo-patterned pseudo-solid- state electrolyte increases the versatility of ionogels and potentially enables new fabrication routes for electrochemical device architectures.