Ricerca
Computational modeling of Battery Chemistry.
The research on metal-oxygen batteries has undergone a dramatic boost in the last decade, mainly due to the outstanding improvements that they would allow, compared to actual lithium-ion batteries, in terms of energy density, costs and materials sustainability. Lithium-oxygen batteries, in particular, are seen as one of the most promising technologies for next-generation energy storage devices, because of their very high theoretical energy density values (~ 3500 Wh/kg).
However, to date, there still remain some major hindrances that heavily undermine the practical development of lithium-oxygen batteries especially in terms of reversibility and energetical efficiency.
However, researchers still lack a clear understanding of how this mediated oxidation of the reduced oxygen species proceeds from a mechanistic point of view. The overall scenario still appears to be largely fragmentary, with experimental evidence often heavily relying on the different cell setups.
Computational simulations can represent an extremely useful tool to predict data which are hardly accessible to experimental techniques, especially for such complicated systems as electrochemical cells. Moreover, such data should provide a possible general criteria to rationalize the often inconsistent set of experimental observations.
New Materials based on biocompatible ionic liquids
The remarkable properties of room temperature ionic liquids (RTIL), including their low volatility, thermal stability and versatility, have raised high expectations for industrial applications, fuelling, in turn, a vast research effort. The already low environmental impact of these compounds, arguably the first and foremost reason of their widespread appeal could perhaps be further reduced by designing ionic liquids made entirely of bio-organic species, whose affinity for biological molecules could open new vistas in pharmacology applications. These ideas have found a first and partial realization in the synthesis and characterization of ionic liquids made by amino acid anions in combination with cations such as [emim]+, [P4,4,4,4] +, etc. that have been already extensively used in more traditional RTIL’s.
We focus on a different family of ionic compounds, consisting of amino acid anions joined to a protonated choline or phospho-coline cation. With respect to the previous cation choices, choline plays an important role in metabolism, is present in a wide variety of living organism, and thus provides a more comprehensive implementation of a biologically compatible material. Moreover, like many other organic molecules, choline can be modified into a series of analogue species, adding one more dimension to the choice of amino acid- based ionic systems. Compounds of this type have been synthesized at the Chemistry Department, Università di Roma "La Sapienza", and their macroscopic and microscopic properties are being measured and characterized.
The richness and variety of bio-organic molecules suggest that the results of this study and of the few previous experimental investigations represent only the first steps into a vast and still unexplored territory, in which the interplay of ionic bonding, amphoteric character and affinity for biological structures and processes could greatly extend the already vast range of RTIL applications.
Atomistic simulation of ionic liquids
Ionic liquids (ILs) are one of the most promising class of new materials investigated in the last decade. They challenge the conventional descriptions of fluids under many points of view thus justifying the need for a wide exploration of their chemical physical properties at a the nanoscopic level. Conventionally, ILs are chemicals that show a melting point lower than 100 C, therefore often liquid under ambient conditions and that are composed entirely of ionic species. Their very low (in many cases, negligible) vapor pressure, high thermal stability, large tunability of several properties (including polarity, hydrophobicity, density, solvating activity) upon slight changes in the chemical architecture prompt the proposal of these materials as solvents for a constantly increasing range of applications. Among the applications of ILs, catalysis, synthesis, sensoristics, electrochemistry and green chemistry (eco-friendly) are the most important. Therefore, it is clear that the range of physico-chemical properties to be rationalized, as regards their microscopic characteristics, is extremely wide and requires a joint use of complementary techniques.
Among these appealing properties, the negligible vapour pressure and the possibility to choose ILs with limited affinity to a variety of commonly used organic solvents make these materials highly cited as environmentally responsible replacements for many noxious volatile organic solvents.
