(606c) Nanoscale Organic Hybrid Electrolytes for Lithium Metal Batteries

Nanoscale hybrid electrolyes have been synthesized that show promise for use in lithium metal batteries. Nanoparticle organic hybrid materials (NOHMs) were created with silica nanocores covalently bonded to polyethylene glycol oligomers (the corona). NOHMs were purified by precipitation in ethanol to remove free organic material, then doped to 1 M LiTFSI in the organic phase. Unlike traditional composite polymer electrolyes, NOHMs based electrolytes are homogenous with evenly distributed, non-agglomerated nanoparticles [1]. Suspension of the NOHMs in free polyethylene glycol dimethyl ether (PEGDME) with 1 M LiTFSI results in a family of materials with properties ranging from liquid-like to solid-like. At a critical NOHMs fraction, the blend is jammed and the electrolytes display soft-glassy rheology. This jamming phenomenon results in a 6 order of magnitude increase in storage modulus with only a fractional decrease in ionic conductivity. The electrolyte properties could be further altered by changes to the dilutant, core size and chemistry, and corona length and chemistry. This level of mechanical tunability may be used to study the effect of modulus and yield stress on dendrite growth upon cycling of lithium metal cells. In addition, as dendritic lithium growth initiates from uneven mass transport pathways of Li+ to the electrode interface, the length scale of homogeneity in the transporting organic phase and its effect on lithium plating may be studied by varying spacing between the inorganic cores. [1] J. L. Nugent, S. S. Moganty, and L. A. Archer. Nanoscale Organic Hybrid Electrolytes. Adv. Mater. In Press.