"Soggy sand" electrolytes with mesoporous silica fillers

C. Pfaffenhuber, J. Popovic

"Soggy sand" electrolytes are potential lithium battery electrolytes consisting of electrically insulating oxide particles, lithium salt and an aprotic organic solvent.Locally, the heterogeneous doping by SiO₂ admixture enhances the dissociation of ion pairs through adsorption of anions on the oxide particle surface resulting in connected diffuse charge clouds of lithium around the particles, allowing its fast transport. On the macroscopic level, the formation of a percolating particle network leads to improved conductivities. Mesoporous silica particles can have conductivity and transference number enhancement effects of the same order of magnitude as seen in small silica nanoparticles depending on the particle morphology, uniformity and pore size. When MSU-H particles (S_BET=570 m²/g) are dispersed in low volume fractions (ϕ) the composite material exhibits high mechanical stability in gelatinous state and can be kept over weeks without noticeable changes of properties.

Figure: Conductivity enhancement upon addition of MSU-H particles to 1 M LiOTf / PEG-150 liquid electrolyte. Lower left corner: TEM micrograph of one worm-like MSU-H particle. Upper right corner: according to the added particle amount, the consistency of the composite electrolyte ranges from liquid (2 vol%) to gel-like (2.8 vol%).

Figure: Conductivity enhancement upon addition of MSU-H particles to 1 M LiOTf / PEG-150 liquid electrolyte. Lower left corner: TEM micrograph of one worm-like MSU-H particle. Upper right corner: according to the added particle amount, the consistency of the composite electrolyte ranges from liquid (2 vol%) to gel-like (2.8 vol%).

Publications:

A. Bhattacharyya, J. Maier, Adv. Mater., 2004, 16, 811. DOI: 10.1002/adma.200306210

C. Pfaffenhuber, F. Hoffmann, M. Fröba, J. Popovic, J. Maier, J. Mat. Chem. A, 2013, 1, 12560. DOI: 10.1039/C3TA11757J

C. Pfaffenhuber, J. Popovíc, and J. Maier, MPG-FKF Annual Report 2013