(642b) An in-Situ-Polymerized Ionic Liquid Bridging Inter-Smectic Domain Gaps for Continuous Charge Transport Pathways As High-Performance Solid-State Electrolytes

The development of an efficient electrolyte that combines fast charge transport and high stability for advanced energy devices remains a huge challenge because these two qualities are traded off during the normal design process. Solid-state electrolytes have emerged as promising alternatives to existing liquid electrolytes for stability improvement in advanced energy devices. However, solid-state electrolytes have difficulties in competing with liquid electrolytes in efficiency considering the low conductivity and poor interfacial contact.

Ionic liquid crystals (ILCs), quasi-solid-state matters combining features of nanostructured liquid crystals and nonvolatile ionic liquids, are expected to offer ideal platforms satisfying the demands of stability, conductivity and interfacial contact for high-performance electrolytes. However, ionic liquid crystals suffered from limited performance in energy devices due to the charge transport barrier at polydomain interfaces. Herein a novel and processable approach was proposed by using a poly(ionic liquid) to imbed ion tunnels at inter-smectic domains to bridge charge transport gaps for ionic liquid crystals. The poly(ionic liquid) was designed and in-situ prepared in a smectic [C₁₄MIm][I] based electrolyte to self-assemble microphase-segregation nanostructures, wherein the poly(ionic liquid) aggregated at the boundaries of layered smectic polydomains. The ions in the poly(ionic liquid) acted as imbedded ion tunnels, which facilitated the charge transport crossing the interfacial gaps to join the intra-domain lamellar channels. Thus, thermally-stable and long-range continuous charge transport pathways were spontaneously constructed to significantly improve the charge transport in the electrolyte. By using the poly(ionic liquid) to bridge the domain-interfacial gaps, the ion conductivity of the electrolyte was up to 7 times increased with a maximum value of 2.0×10^-3 S cm^-1. The approach to prepare high-performance solid-state electrolytes were tested in dye-sensitized solar cells, and the performance of the derived dye-sensitized solar cell was thermally stable and the efficiency was about 2 times enhanced with a champion efficiency of 8.2%.

The work here demonstrated a convenient and effective approach to overcome the inter-domain charge transport issue in ionic liquid crystals as high-performance electrolytes integrating efficiency and durability.