No abstract

Magnesium borohydride ammonia borane, Mg-(BH 4 ) 2 (NH 3 BH 3 ) 2 , was electrochemically investigated. Impedance measurements of the mechanochemically synthesized Mg-(BH 4 ) 2 (NH 3 BH 3 ) 2 exhibited an ionic conductivity of 1.3 × 10 −5 S cm −1 at 30 °C. Electrochemical cells fabricated with Mg-(BH 4 ) 2 (NH 3 BH 3 ) 2 as the solid electrolyte demonstrated reversible Mg migration through the material, indicating its potential for use as a Mg ionic conductor in all-solid-state Mg-ion batteries.

High-energy-density and low-cost calcium (Ca) batteries have been proposed as ‘beyond-Li-ion’ electrochemical energy storage devices. However, they have seen limited progress due to challenges associated with developing electrolytes showing reductive/oxidative stabilities and high ionic conductivities. This paper describes a calcium monocarborane cluster salt in a mixed solvent as a Ca-battery electrolyte with high anodic stability (up to 4 V vs. Ca2+/Ca), high ionic conductivity (4 mS cm−1), and high Coulombic efficiency for Ca plating/stripping at room temperature. The developed electrolyte is a promising candidate for use in room-temperature rechargeable Ca batteries.

Li 2 B 12 H 12 and its derivatives are promising solid electrolytes for solid-state batteries. In this work, a potential model is proposed, and an extensive classical molecular dynamics study is performed to understand the origin of the fast ion conduction in Li 2 B 12 H 12 . The proposed potential model reveals structural and dynamical properties of Li 2 B 12 H 12 that are consistent with first-principles molecular dynamics simulation and experimental results. The mechanism of Li + -ion transport is studied systematically. The low-temperature α phase exhibits negligible diffusivity within a timescale of a few nanoseconds, whereas the high-temperature β phase with a similar crystal structure and larger lattice parameter exhibits entropy-driven high Li + -ion diffusion assisted by anionic reorientation. We explicitly demonstrate the role of closo-borane anionic reorientational motion in the Li + -ion diffusion and explain how the cell parameter facilitates the anionic reorientational motion. In addition, enhancing the degree of H freedom (by changing the B-B-H angular force parameters) results in significantly high cationic diffusivity at low temperature. Further insight into Li + -ion transport is obtained by constructing a three-dimensional density map and determining the free-energy barrier, and the factors affecting cationic diffusion are thoroughly investigated with high precision using long simulations (5 ns).