Deep eutectic solvents (DESs) added with lithium salts are emerging as alternative electrolytes for lithium-ion batteries (LIBs). Yet, to design, optimize, and develop efficient DES-based electrolytes for LIBs, an in-depth understanding of the role played by the lithium cations in the intermolecular interactions between all species in the mixture is crucial. A joint approach of experimental NMR techniques and polarizable molecular dynamics (MD) simulations is used here to gather a comprehensive picture of the structure and dynamics of the prototypical system composed of the DES choline chloride:urea (ChCl:U, x ChCl = 0.33) and the lithium salt containing the same anion, LiCl. Strong coordination of lithium cations by chloride anions, resulting in the formation of LiCl 3 2− units, is revealed. Other species (especially, urea) are present in the second coordination shell of lithium, creating an extensive hydrogen-bond network. The effect of small quantities of water, typically absorbed by DES from air moisture, on the studied properties is discussed.

Protic ionic liquids (PILs) are potential candidates as electrolyte components in energy storage devices. When replacing flammable and volatile organic solvents, PILs are expected to improve the safety and performance of electrochemical devices. Considering their technical application, a challenging task is the understanding of the key factors governing their intermolecular interactions and physicochemical properties. The present work intends to investigate the effects of the structural features on the properties of a promising PIL based on the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBUH + ) cation and the (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide (IM14 – ) anion, the latter being a remarkably large anion with an uneven distribution of the C–F pool between the two sides of the sulfonylimide moieties. For comparison purposes, the experimental investigations were extended to PILs composed of the same DBU-based cation and the trifluoromethanesulfonate (TFO – ) or bis(trifluoromethanesulfonyl)imide (TFSI – ) anion. The combined use of multiple NMR methods, thermal analyses, density, viscosity, and conductivity measurements provides a deep characterization of the PILs, unveiling peculiar behaviors in DBUH-IM14, which cannot be predicted solely on the basis of differences between aqueous p K a values of the protonated base and the acid (Δp K a ). Interestingly, the thermal and electrochemical properties of DBUH-IM14 turn out to be markedly governed by the size and asymmetric nature of the anion. This observation highlights that the structural features of the precursors are an important tool to tailor the PIL’s properties according to the specific application.

Choline-based deep eutectic solvents (DESs) are potential candidates to replace flammable organic solvent electrolytes in lithium-ion batteries (LIBs). The effect of the addition of a lithium salt on the structure and dynamics of the material needs to be clarified before it enters the battery. Here, the archetypical DES choline chloride:urea at 1:2 mole fraction has been added with lithium chloride at two different concentrations and the effect of the additional cation has been evaluated with respect to the non-doped system via multinuclear NMR techniques. 1H and 7Li spin-lattice relaxation times and diffusion coefficients have been measured between 298 K and 373 K and revealed a decrease in both rotational and translational mobility of the species after LiCl doping at a given temperature. Temperature dependent 35Cl linewidths reflect the viscosity increase upon LiCl addition, yet keep track of the lithium complexation. Quantitative indicators such as correlation times and activation energies give indirect insights into the intermolecular interactions of the mixtures, while lithium single-jump distance and transference number shed light into the lithium transport, being then of help in the design of future DES electrolytes.

No abstract

A cana-de-açúcar é a principal matéria-prima para produção de etanol no Brasil, entretanto ela possui restrições quanto ao seu ciclo de produção. Dessa forma, o sorgo sacarino, pode ser visto como uma alternativa durante as entressafras canavieira. Utilizando o software Aspen HYSYS, foi realizada a simulação da produção integrada de etanol de primeira e segunda geração a partir do sorgo sacarino. Para produção do último, o bagaço do sorgo deve ser submetido a um pré-tratamento. Nesse trabalho, foram avaliados os pré-tratamentos hidrotérmico, ácido diluído e explosão a vapor; cujos custos de produção integrada foram estimados, após análise econômica, em US$1,205, US$1,244 e US$1,367, por quilo de etanol, respectivamente. Pela variação paramétrica, observou-se que a produção de etanol é economicamente viável para maiores quantidades de material processado. O menor valor obtido foi US$0,987/kg etanol, utilizando o pré-tratamento hidrotérmico, processando 650 ton/h de sorgo sacarino.