Synthesis, characterization and formulation of a cathode active material: Copper nitroprusside

Nowadays, rechargeable Li-ion batteries play an important role in portable consumer devices. Formulation of such batteries is improvable by researching new cathodic materials that present higher performances of cyclability and negligible efficiency loss over cycles. Goal of this work was to investigate a new cathodic material, copper nitroprusside, which presents a porous 3D framework. Synthesis was carried out by a low-cost and scalable co-precipitation method. Subsequently, the product was characterized by means of different techniques, such as TGA, XRF, CHN elemental analysis, XRD, Mössbauer spectroscopy and cyclic voltammetry. Electrochemical tests were finally performed both in coin cells and by using in situ cells: on one hand, coin cells allowed different formulations to be easily tested, on the other operando cycling led a deeper insight to insertion process and both chemical and physical changes. Results of several tests highlighted a non-reversible electrochemical behavior of the material and a rapid capacity fading over time. Moreover, operando techniques report that amorphisation occurs during the discharge.

Una nuova formulazione semplificata per la soluzione del problema di Maxwell non omogeneo

Il problema di Maxwell canonico si suddivide nel problema di Maxwell omogeneo e nel problema di Maxwell non omogeneo, o della radiazione, a seconda che siano presenti le correnti impresse. Il problema della radiazione ci mostra come si può generare un’onda elettromagnetica. In questo elaborato si risolverà il problema di Maxwell non omogeneo utilizzando un metodo relativamente nuovo che sfrutta la funzione di Green e la funzione generalizzata tridimensionale di dirac. Tramite quest'ultima, vedremo come sarà possibile riscrivere l’elemento infinitesimo di corrente impressa.

Formulation of ionogel, hydrogel and films using a cellulose rich solid obtained from Pinus radiata

The purpose of my internship, carried out during my Erasmus period at the Complutense University of Madrid, was focused on the formulation of ionogels and hydrogels for the obtainment of films with high lignin content, and on their characterization measuring their antibacterial properties. For biomass formulation I used lignocellulosic biomass (Pinus Radiata) as raw material and ionic liquid as solvent. The two ionic liquids proposed were: 1-ethyl-3-methylimidazoliumdimethylphosphate [Emim][DMP] and 1-ethyl-3-methylimidazoliumdiethylphosphate [Emim][DEP]. The two-starting cellulose-rich solids were obtained from Pinus radiata wood that had been submitted to an organosolv process, to reduce its lignin content to fifteen (ORG15) and twenty per cent (ORG20). Having two ionic liquids and two solids available, the first phase of the project was devoted to the screening of both solids in both ionic liquids. Through this, it was possible to identify that only the [Emim][DMP] ionic liquid fulfils the purpose. It was also possible to discard the cellulose-rich solid ORG20 because its dissolution in the ionic liquid was not possible (after the time fixed) and, additionally, a Pinus radiata cellulose-rich solid bleached with hydrogen peroxide and containing ten per cent of lignin (ORG10B) was included in the screening. After screening, a total of five ionogels were subsequently formulated: two gels were formulated with the starting raw material ORG15 (with 1% and 1.75% cellulose, respectively) and three with ORG10B (with 1%, 1.75% and 3% cellulose, respectively). Five hydrogels were obtained from the ionogels. Rheological tests were performed on each ionogel and hydrogel. Finally, films were formulated from hydrogels and they were analysed by antibacterial testing to see if they could be applied as food packaging. In addition, antioxidant and properties such as opacity and transparency were also studied.