Alessandro Mariani

Bio: Alessandro Mariani is an academic researcher from Karlsruhe Institute of Technology. The author has contributed to research in topics: Ionic liquid & Electrolyte. The author has an hindex of 13, co-authored 40 publications receiving 435 citations. Previous affiliations of Alessandro Mariani include European Synchrotron Radiation Facility & Sapienza University of Rome.

Concentrated Ionic‐Liquid‐Based Electrolytes for High‐Voltage Lithium Batteries with Improved Performance at Room Temperature

Abstract: Ionic liquids (ILs) have been widely explored as alternative electrolytes to combat the safety issues associated with conventional organic electrolytes. However, hindered by their relatively high viscosity, the electrochemical performances of IL‐based cells are generally assessed at medium‐to‐high temperature and limited cycling rate. A suitable combination of alkoxy‐functionalized cations with asymmetric imide anions can effectively lower the lattice energy and improve the fluidity of the IL material. The Li/Li$_{1.2}$Ni$_{0.2}$Mn$_{0.6}$O$_{2}$ cell employing N‐N‐diethyl‐N‐methyl‐N‐(2‐methoxyethyl)ammonium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (DEMEFTFSI)‐based electrolyte delivered an initial capacity of 153 mAh g$^{-1}$ within the voltage range of 2.5–4.6 V, with a capacity retention of 65.5 % after 500 cycles and stable coulombic efficiencies exceeding 99.5 %. Moreover, preliminary battery tests demonstrated that the drawbacks in terms of rate capability could be improved by using Li‐concentrated IL‐based electrolytes. The improved room‐temperature rate performance of these electrolytes was likely owing to the formation of Li$^{+}$‐containing aggregate species, changing the concentration‐dependent Li‐ion transport mechanism.

Pressure-induced mesoscopic disorder in protic ionic liquids: first computational study

Abstract: It has been recently shown that pressure may affect the mesoscopic heterogeneity in aprotic ionic liquids, owing to the long alkyl chain folding on itself. Here we explore protic ionic liquids, using classical molecular dynamics. These compounds have shorter and stiffer alkyl chains, harder to fold. We observed that high pressure affects the mesoscopic structure of the studied chemicals and, indeed, the effect may be ascribed to chain folding.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

TRAVIS-A free analyzer for trajectories from molecular simulation.

Abstract: TRAVIS (“Trajectory Analyzer and Visualizer”) is a program package for post-processing and analyzing trajectories from molecular dynamics and Monte Carlo simulations, mostly focused on molecular condensed phase systems. It is an open source free software licensed under the GNU GPL, is platform independent, and does not require any external libraries. Nine years after the original publication of TRAVIS, we highlight some of the recent new functions and features in this article. At the same time, we shortly present some of the underlying algorithms in TRAVIS, which contribute to make trajectory analysis more efficient. Some modern visualization techniques such as Sankey diagrams are also demonstrated. Many analysis functions are implemented, covering structural analyses, dynamical analyses, and functions for predicting vibrational spectra from molecular dynamics simulations. While some of the analyses are known since several decades, others are very recent. For example, TRAVIS has been used to compute the first ab initio predictions in the literature of bulk phase vibrational circular dichroism spectra, bulk phase Raman optical activity spectra, and bulk phase resonance Raman spectra within the last few years.

High-voltage liquid electrolytes for Li batteries: progress and perspectives

Abstract: Since the advent of the Li ion batteries (LIBs), the energy density has been tripled, mainly attributed to the increase of the electrode capacities. Now, the capacity of transition metal oxide cathodes is approaching the limit due to the stability limitation of the electrolytes. To further promote the energy density of LIBs, the most promising strategies are to enhance the cut-off voltage of the prevailing cathodes or explore novel high-capacity and high-voltage cathode materials, and also replacing the graphite anode with Si/Si-C or Li metal. However, the commercial ethylene carbonate (EC)-based electrolytes with relatively low anodic stability of ∼4.3 V vs. Li+/Li cannot sustain high-voltage cathodes. The bottleneck restricting the electrochemical performance in Li batteries has veered towards new electrolyte compositions catering for aggressive next-generation cathodes and Si/Si-C or Li metal anodes, since the oxidation-resistance of the electrolytes and the in situ formed cathode electrolyte interphase (CEI) layers at the high-voltage cathodes and solid electrolyte interphase (SEI) layers on anodes critically control the electrochemical performance of these high-voltage Li batteries. In this review, we present a comprehensive and in-depth overview on the recent advances, fundamental mechanisms, scientific challenges, and design strategies for the novel high-voltage electrolyte systems, especially focused on stability issues of the electrolytes, the compatibility and interactions between the electrolytes and the electrodes, and reaction mechanisms. Finally, novel insights, promising directions and potential solutions for high voltage electrolytes associated with effective SEI/CEI layers are proposed to motivate revolutionary next-generation high-voltage Li battery chemistries.