LiSc(BH 4 ) 4 has been prepared by ball milling of LiBH 4 and ScCl 3 . Vibrational spectroscopy indicates the presence of discrete Sc(BH 4 ) 4 -ions. DFT calculations of this isolated complex ion confirm that it is a stable complex, and the calculated vibrational spectra agree well with the experimental ones. The four BH 4 -groups are oriented with a tilted plane of three hydrogen atoms directed to the central Sc ion, resulting in a global 8 + 4 coordination. The crystal structure obtained by high-resolution synchrotron powder diffraction reveals a tetragonal unit cell with a ) 6.076 Å and c ) 12.034 Å (space group P-42c). The local structure of the Sc(BH 4 ) 4 -complex is refined as a distorted form of the theoretical structure. The Li ions are found to be disordered along the z axis.

We introduce a coarse-grained simulation model for the reductive deposition of lithium cations in secondary lithium metal batteries. The model accounts for the heterogeneous and nonequilibrium nature of the electrodeposition dynamics, and it enables simulation of the long timescales and lengthscales associated with metal dendrite formation. We investigate the effects of applied overpotential and material properties on earlystage dendrite formation, as well as the molecular mechanisms that govern this process. The model confirms that dendrite formation propensity increases with the applied electrode overpotential, and it demonstrates that application of the electrode overpotential in time-dependent pulses leads to dramatic suppression of dendrite formation while reducing the accumulated electrode on-time by as much as 96%. Moreover, the model predicts that time dependence of the applied electrode overpotential can lead to positive, negative, or zero correlation between cation diffusivity in the solid−electrolyte interphase (SEI) and dendrite formation propensity. Analysis of the simulation trajectories reveals that dendrite formation emerges from a competition between the timescales for cation diffusion and reduction at the anode/SEI interface, with lower applied overpotentials and shorter electrode pulse durations shifting this competition in favor of lower dendrite formation propensity. This work provides a molecular basis for understanding and designing pulsing waveforms that mitigate dendrite formation while minimally affecting battery charging times.

The correspondence between the exact embedding potential and the pair of the electron densities--that of the embedded molecule and that of its environment [Wesolowski and Warshel, J. Phys. Chem. 1993, 97, 8050]--is used to generate the average embedding potential and to subsequently calculate the solvatochromic shifts in a number of organic chromophores in solvents of various polarities. The averaged embedding potential is evaluated at a fictitious electron density of the solvent, which is obtained by means of "dressing up" with electrons the classical site distributions derived from the statistical-mechanical, 3D molecular theory of solvation (aka 3D-RISM method) [Kovalenko In Molecular Theory of Solvation; Hirata, Ed.; Understanding Chemical Reactivity; 2003, Vol 24], self-consistently coupled with the electronic structure of the solute. The proposed approach to modeling solvatochromic shifts can be situated between the implicit and explicit type of models for the solvent. Numerical examples are given for the lowest-lying n --> pi* and pi --> pi* excitations.