High transference numbers in composite electrolytes

J. Popovic, G. Gregori

Salt containing liquid electrolytes show both cation and anion conductivity leading to concentration polarization effects, a severe problem in context of Li-based batteries. Such adverse effects can be circumvented through development of composite electrolytes in which porous insulating solid with favorable surface chemistry is covered by a thin layer of liquid electrolyte allowing for the overlap and percolation of highly Li⁺ conductive space charge zones.

Figure 1: Sketch of a typical dependence of Li transference number on filler volume fraction in "soggy sand" electrolytes.

Of particular interest are the galvanostatic DC polarization measurements of composite electrolytes (highly concentrated "soggy sand" electrolytes) performed in a specially designed cell under controlled atmosphere.

Figure 2: Symmetrical DC polarization cell. The wetted solid sample (middle) is sandwiched between lithium foils.

Publications:

C. Pfaffenhuber, M. Göbel, J. Popovic, J. Maier, Phys. Chem. Chem. Phys., 2013, 15, 18318. DOI: 10.1039/C3CP53124D