Unravelling the structural and dynamical complexity of the equilibrium liquid grain-binding layer in highly conductive organic crystalline electrolytes

Abstract

A nanolayer of surface liquid phase in equilibrium with the bulk solid is responsible for the low grain boundary resistance in the solid electrolyte LiCl·DMF, as supported by a combination of experiment, theory, and modelling.

Experimental and Theoretical Investigation of the Ion Conduction Mechanism of Tris(adiponitrile)perchloratosodium, a Self-Binding, Melt-Castable Crystalline Sodium Electrolyte

“…The presence of adiponitrile-based nanoliquid at the crystalline surface is supported by DSC analysis, which shows melting and freezing signals for liquid adiponitrile even after rinsing of the crystals. This nanoliquid surface solution of NaClO 4 is analogous to previous crystalline electrolytes that we have reported. , The grain size is of the order of 100 μm.…”

A Soft-Solid Co-Crystalline Electrolyte Combining Advantages of Organics and Ceramics: Thermally, Electrochemically Stable, Highly Conductive (Adiponitrile)2LiPF6

“…In addition, model V also shows that the cocrystals at room temperature possess a liquid-like surface layer (Figure S8b) similar to other soft solid cocrystals 14 , and which is also seen from SEM analysis of this electrolyte (Figure S5 and S6). This nanoliquid surface behavior is a general characteristic of this class of electrolytes 11,12,14,47 . To determine the structure of the intergranular interface, model V8g (surface model) with eight nano-sized grains (1 grain = 5x5x5 unit cells) were simulated in a vacuum box of 30x30x30 nm 3 (Figure 3a).…”

Solvate sponge crystals of (DMF)3NaClO4: reversible pressure/temperature controlled juicing in a melt/press-castable sodium-ion conductor

“…Advancements in the development of electrolytes and cocrystals have been accelerated with computer simulation methods like molecular dynamics (MD) simulations, which elucidate the mechanisms of thermal decomposition and ion conduction. In previous work, 24 thermal behavior and ion conduction in a cocrystalline electrolyte DMF·LiCl for lithium ion batteries were measured experimentally and modelled using classical MD simulations and gas phase DFT calculations. While MD simulations provided a molecular-level understanding of melting/decomposition and of a surface nanoliquid layer facilitating grain binding in pressed pellets, DFT calculations provided atomic scale explanation of ionic clusters on the surface and in the bulk phase that contribute to ionic conductivity.…”