The application of high lithium transference number electrolytes in lithium ion batteries is greatly beneficial as they would prevent the occurrence of salt concentration gradients which may limit battery cell lifetime and energy density. In “soggy sand” electrolytes (insulating oxide nanoparticles dispersed in typically organic lithium salt solution), lithium transference number close to unity is expected to be achievable at high volume fractions as a consequence of disappearing bulk conductivity.[1] Such a trend has already been observed in the 1 M LiTf/PEGDME-150 containing mesoporous MSU-H nanoparticles.[2] A convenient way of circumventing particle network reproducibility and stationarity is by infiltration of monolithic hierarchically porous SiO₂ (with various surface modifications) or Al₂O₃ with 1 M LiTf/PEGDME-150 leading to liquid-solid electrolytes with very high lithium transference number (0.75 to 0.89) without compromising high room temperature ionic conductivity (0.32 to 0.48 mS cm^-1).[3] Additionally, importance of indirect (vehicular) transport mechanism of lithium and deconvolution of contributions of free ions and ion pairs to the overall conduction in LiTf/PEGDME-150 liquid electrolyte by a combination of experimental techniques (impedance spectroscopy, dc polarization, pulse field gradient NMR) will be discussed.[4] The pertinence of liquid/solid electrolytes is remarkable as they could make lithium battery separators dispensable offering form stability and excellent contact with high power nanostructured electrodes.     

1. C. Pffafenhuber, M. Göbel, J. Popovic, J. Maier,  Physical Chemistry Chemical Physics, 15(42), 18318–18335, 2013.
2. C. Pfaffenhuber, F. Hoffmann, M. Fröba, J. Popovic, J. Maier, Journal of Materials Chemistry A, 1(40), 12560–12567, 2013.
3. J. Popovic, G. Hasegawa, I. Moudrakovski, J. Maier, Advanced Materials, submitted
4. J. Popovic, C. Pfaffenhuber, J. Melchior, J. Maier, Electrochemistry Communications, 60, 195–198, 2015.