This workshop convened leading experts in solid state ionics, low-cost ceramics and composites manufacturing, mechanical properties of thin functional layers, mixed ionic and electronic conductors, nanostructuring, solid-state polymers, solid-state synthetic techniques, high-throughput materials computation and discovery, and novel approaches to ionically conductive layers to identify innovative research paths to advance solid ion conductors for energy technologies. Participants lent their expertise to help formulate performance and cost targets across the various applications and explore specific technology pathways to inform potential ARPA-E projects in this area. 

Ions of specific interest included Li⁺, H⁺, Na⁺, Mg²⁺, F⁻, and O²⁻; other ions were also of interest provided they had relevance to energy technologies.  Mixed ionic and electronic conductors were also of interest. 

Energy technology applications of interest included all-solid-state batteries, batteries with different liquid electrolytes for the anode and cathode, fuel cells (based on various conducting ions), separations (e.g., oxygen purification), reactions (e.g., oxidative coupling of methane), electroplating, electrochromic devices, and more.

Features of solid ion conducting layers of interest included a high ionic (and possibly electronic) conductivity, good mechanical properties, ability to fabricate a thin layer (possibly of different geometries, such as sheets or tubes), chemical compatibility with adjacent materials, and low cost.

Additional information on this workshop was presented at the MRS Conference in Boston on December 1, 2015 by Program Director Paul Albertus. 
Title: ARPA-E Program Proposal: Selective Ion Conductors and the Future of the Electrochemical Cell

A summary of the event and presentation slides are available below.