Gas phase analogs of stable sodium-tin Zintl ions: Anion photoelectron spectroscopy and electronic structure

Benchmark computational investigations for the basic model of the salt-water complex: NaCl(H2O) and its anion NaCl(H2O). Phys Chem Chem Phys 2023;25:27215-27229. [PMID: 37791409 DOI: 10.1039/d3cp03421f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The microsolvation of salts in water is a fundamental physicochemical process. In this work, the aqueous salt complex NaCl(H2O) and its anion NaCl(H2O)- were investigated using comprehensive calculations, including the costly and accurate CCSD(T)-F12a and focal point analysis (FPA) methods. For the neutral NaCl(H2O), three isomers exist, two of which are mirror-symmetric with almost identical structures and their corresponding anions are also mirror-symmetric. For the NaCl(H2O)- anion, there are four isomers. Several transition states are found for the first time. The structural rearrangements of neutral NaCl(H2O) and NaCl(H2O)- anions are mainly caused by breaking and forming of the hydrogen bonds and the enhancement and weakening of interactions between Na and O atoms. The distributions of the anion complexes from 15-300 K are computed and compared to recent experimental results. The analysis of the intermolecular weak interactions shows the weak van der Waals interactions between Na and O atoms, as well as hydrogen bonding between H and Cl. Moreover, the theoretically predicted anion photoelectron spectra are assigned and analyzed in detail, and they agree with experimental spectra satisfactorily. The Na-Cl stretching vibrational mode dominates the vibrational structure in both anion spectra with some minor contributions from the intermolecular motions between H2O and NaCl.

Formation of Zintl Ions and Their Configurational Change during Sodiation in Na-Sn Battery

Despite their large theoretical storage capability, Na-Sn batteries exhibit poor round-trip energy efficiencies as compared to Li-Si batteries. Here, we report the results of a comprehensive study to elucidate how and why Na-Sn batteries exhibit such a low energy efficiency. As a convincing evidence for this behavior, we observed that the resistivity of the Sn anode increased by 8 orders of magnitude during in situ sodiation experiments, which is attributed to the formation of electrically resistive Zintl ions in the sodiated Sn. Continual sodiation induced the development of residual stresses at the Sn anode and caused the distortion of Zintl ions from their ideal configuration. This distortion caused a change in the electronic structure, resulting in the increased resistivity of the sodiated Sn. Our findings offer some solutions that can be used to improve the energy efficiency of Na-Sn batteries.

Structural stability and bonding nature of Li–Sn–carbon nanocomposites as Li-ion battery anodes: first principles approach

The atomic structural stability and electronic properties of Li_nSn₄–carbon nanotube (CNT) and Li_nSn₄–graphene nanocomposites were studied by first principles calculations.

18-Electron rule inspired Zintl-like ions composed of all transition metals

The 18-electron rule is applied to design a new class of all transition metal based Zintl-like ions.