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

Fall, Birane; Prakash, Prabhat; Aguirre, Jordan C.; Chereddy, Sumanth; Chinnam, Parameswara Rao; Dikin, Dmitriy A.; Venkatnathan, Arun; Wunder, Stephanie L.; Zdilla, Michael J.

doi:10.26434/chemrxiv-2021-n0d4x

Cited by 2 publications

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“…In another work, a similar solvent-assisted migration of the Li + ion has also been observed, where the cyano group on adiponitrile supports the migration of Li + ions to an occupancy site at a distance of >0.6 nm, without any interference from anions. 28 Despite having a close agreement for E a,exp and E a,DFT for (DMF) 3 NaClO 4 , poor agreement with E a from MD simulations was still an unsolved question. We hypothesized that the MD simulations at and above room temperature do not exclusively manifest just the Na + ion conduction in (DMF) 3 NaClO 4 because the simulations have also shown that around room temperature the crystals form a dynamic equilibrium with 2:1 stoichiometry as well.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…We also described that these crystals and others like them exhibit a nanoliquid surface layer resulting from the decreased lattice energy at the surface, which we have detected experimentally (SEM) and described using MD simulations on several materials. 28,29 This surface nanoliquid layer at the grain boundaries naturally binds grains to one another and facilitates ion conduction across electrolyte particles, circumventing the grain-boundary problem common to other solid electrolyte systems. Apart from these peculiar structural properties, these cocrystals exhibit a conductivity of 3 × 10 −4 S cm −1 with an E a barrier of 25 kJ mol −1 for Na + ion conduction calculated from temperature-dependent impedance spectroscopy measurements.…”

Section: ■ Introductionmentioning

confidence: 99%

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Mechanism of Ion Conduction and Dynamics in Tris(N,N-dimethylformamide) Perchloratosodium Solid Electrolytes

et al. 2022

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(DMF)3NaClO4 is a soft-solid cocrystalline electrolyte with channels of Na+ ions, which can be reversibly converted to a less conductive form (DMF)2NaClO4 by the application of pressure or heat, leading to a melt- or press-castable electrolyte. Molecular dynamics simulations performed on the 3:1 stoichiometry suggest that Na+ ions conduct via a one-dimensional channel, which is supported by van-Hove autocorrelation function analysis. The simulations show that the transference number for Na+ ions is 0.43 at room temperature and exceeds 0.5 at higher temperatures in the molten mixture. The calculated activation energy for the diffusion of Na+ ions from MD simulations is 45 kJ mol–1. The minimum-energy path of Na+ ion migration in a 3:1 crystal is assessed using periodic density functional theory calculations, which provides a barrier of 33 kJ mol–1 for Na+ ion conduction, in reasonable agreement with the experimental value of 25 kJ mol–1. The motion of Na+ ions during conduction is vacancy-driven because the presence of a vacancy site enables jump events for Na+ ions. The activation energy is the penalty for a sodium ion to leave the octahedrally coordinated DMF ligand field via a transition state where only three molecules of DMF form a 3-O-Na trigonal planar geometry, with no involvement of ClO4 – in the coordination sphere of the transition state. In contrast, the calculated activation energy barrier for the 2:1 stoichiometry is higher (E a,DFT = 43 kJ mol–1, E a,exp = 49 kJ mol–1) due at least in part to the partial coordination of strongly binding perchlorate anions with Na+ ions in the transition state.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%