High Ionic Conductivity Composite Solid-State Electrolytes

We report on the development of a solid-state electrolyte (SSE) with high ionic conductivity, having physical properties that allow their ready integration into current battery devices whose fabrication is amenable to large scale manufacturing. The prototype Composite SSE reported comprises a polymer-Li-salt matrix embedded with super-ionically conducting garnet nanoparticles. We employ polyethylene-oxide (PEO) + LiTFSI (salt) as a matrix incorporating Bi-doped lithium lanthanum zirconium oxide (LLZBO) ceramic nanoparticles (~350nm diameter). We study the role of Bi-aliovalent substitution in LiLaZrO on the microstructure and the ionic conductivity of the ceramic garnet material. We successfully reduce the synthesis temperature of LiLaZrO by Bi-additions utilizing sol-gel reactions. Additions of very small amounts (5% weight load) of the garnet nanoparticles to the polymer-salt matrix result in over two-orders of magnitude increments of the ionic conductivity of the polymer-salt matrix. This composite SSE is amenable to large-scale fabrication and integration into battery devices, furthermore given the small amount of ceramic particles needed, it is cost-competitive.