This phase 2 proposal builds upon Phase 1 successes, with plans for the construction of an electrochemical variable emissivity device (EC VED). The viability of this EC VED will be determined by the development of a new family of ionic liquid (IL) electrolytes featuring polyhedral boron cages as the anionic component. In these new electrolytes, the negligible vapor pressures and high ionic conductivities of standard ILs will be combined with the exceptional stabilities inherent to boron-cage anions. Whereas standard commercial ILs have known degradation pathways, the enhanced stabilities of these new boron cage ionic liquids (BCILs) will allow them to perform repeated tasks over long periods of time without the need for replacement or repair. As these cages may be rationally functionalized, control of the fluid properties of these ILs will rest with the anion, allowing for the replacement of the not long-term-stable imidazolium cation.The first iterations of these BCILs synthesized in Phase 1 enabled the reversible electrodeposition of a silver mirror with no decrease in performance through 1000 cycles. After optimization of the electrolyte and electrode materials in Phase 2, similar performance of the entire device up to 100,000 cycles is envisioned.
