Soggy-sand electrolytes: status and perspectives

Abstract

Soggy-sand electrolytes (solid-liquid composites, typically gel electrolytes, with synergistic electrical properties) are reviewed as far as status and perspectives are concerned. Major emphasis is put on the understanding of the local mechanism as well as the long-range transport along the filler network. The beneficial property spectrum includes enhanced conductivity of one ion type and decreased conductivity of the counter ion, but also the exciting mechanical properties of the solid-liquid composites. Inherent but not insurmountable problems lie in the reproducibility and stationarity of the composites microstructure and morphology. Owing to the huge parameter complexity and hence to the multitude of adjusting screws, there are various strategies for materials optimization. The technological relevance is enormous, in particular for battery electrolytes as here all the above-mentioned electrical and mechanical benefits are welcome. The soggy-sand electrolytes combine high Li(+) conductivity, low anion conductivity and good wettability of electrode particles with the mechanical stability of semi-solids.

Space Charge Layer Effect in Solid State Ion Conductors and Lithium Batteries: Principle and Perspective

“…31 Here, it is worthwhile mentioning "Soggy Sand Electrolytes". 32,33 The total conductivities are highly increased by virtue of the very high conductivities at the edge of the space charge profiles. This work is of significance owing to evidence of heterogeneous doping mechanism as well as improvement of mechanical behaviour for the polymer electrolytes in the field of solid-state lithium batteries.…”

Determination of individual contributions to the ionic conduction in liquid electrolytes: Case study of LiTf/PEGDME-150

“…Overall ionic conduction and lithium transference number are enhanced by addition of 1 vol% SiO 2 to 1 M LiTf/PEGDME-150 to values of σ AC = 0.79 mS cm −1 and t pol+ = 0.51, respectively. "Soggy sand" effect is clearly shown through increased cationic conductivity, σ + = 0.28 mS cm −1 and enhanced lithium transport via free ions, t + = 0.28, while as expected [24] σ − = 0.51 mS cm −1 and s = 0.20 mS cm −1 are hardly changed since they are dominated by the bulk.…”

“…Electrochemical implications of ion pairing have been investigated in salt containing solid polyethylene oxide (PEO) electrolytes by Bruce [4,5] as well as more recently by Stolwijk et al [6][7][8], in oligoethers by Watanabe et al [9][10][11], and by Saito et al [12][13][14][15] employing electrophoretic NMR. This particular electrolyte (lithium salt containing poly(ethylene glycol) dimethyl ether) has been used for a variety of battery systems, most recently in Li-O 2 [16][17][18][19][20] and more generally as a component of "soggy sand" electrolytes [21][22][23][24][25].…”

A Few Case Studies on the Correlation of Particle Network and Its Stability on the Ionic Conductivity of Solid–Liquid Composite Electrolytes

“…In the case of larger micrometer sized additive particles, the mechanical consistency of the composite resembles that of "soggy sand" [1]. Of course, the liquid to gel is not really one step transformation and several intermediate colloidal (sol) states precede the gel state [1,2]. Interestingly, several solid-liquid composite electrolyte in the gel/"soggy sand" state exhibits ambient temperature composite ionic conductivity higher than the starting liquid electrolytes [1,2].…”

“…"Soggy sand" electrolytes [1,2] are widely considered an important and distinct class of soft matter electrolytes [3].It is essentially a solid-liquid composite electrolyte comprising of fine oxide particles such as silica dispersed in a non-aqueous liquid salt solution [2]. The range of oxide additives and solvents are diverse both from the point of view of physical properties and chemical composition.…”