Superionic Solid Electrolyte Li7La3Zr2O12 Synthesis and Thermodynamics for Application in All-Solid-State Lithium-Ion Batteries

Li7La3Zr2O12Solid-state reaction was used for Li7La3Zr2O12 material synthesis from Li2CO3, La2O3 and ZrO2 powders. Phase investigation by XRD, SEM and EDS methods of Li7La3Zr2O12 were carried out. The molar heat capacity of Li7La3Zr2O12 at constant pressure in the temperature range 298-800 K should be calculated as Cp,m = 518.135+0.599 × T - 8.339 × T−2, where T is absolute temperature, . Thermodynamic characteristics of Li7La3Zr2O12 were determined as next: entropy S0298 = 362.3 J mol-1 K-1, molar enthalpy of dissolution ΔdHLlZO = ˗ 1471.73 ± 29.39 kJ mol−1, the standard enthalpy of formation from elements ΔfH0 = ˗ 9327.65 ± 7.9 kJ mol−1, the standard Gibbs free energy of formation ∆f G0298 = ˗9435.6 kJ mol-1.

Continuum Thermodynamics of Constrained Reactive Mixtures

Mixture theory models continua consisting of multiple constituents with independent motions. In constrained mixtures all constituents share the same velocity but they may have different reference configurations. The theory of constrained reactive mixtures was formulated to analyze growth and remodeling in living biological tissues. It can also reproduce and extend classical frameworks of damage mechanics and viscoelasticity under isothermal conditions, when modeling bonds that can break and reform. This study focuses on establishing the thermodynamic foundations of constrained reactive mixtures under more general conditions, for arbitrary reactive processes where temperature varies in time and space. By incorporating general expressions for reaction kinetics, it is shown that the residual dissipation statement of the Clausius-Duhem inequality must include a reactive power density, while the axiom of energy balance must include a reactive heat supply density. Both of these functions are proportional to the molar production rate of a reaction, and they depend on the chemical potentials of the mixture constituents. We present novel formulas for the classical thermodynamic concepts of energy of formation and heat of reaction, making it possible to evaluate the heat supply generated by reactive processes from the knowledge of the specific free energy of mixture constituents as well as the reaction rate. We illustrate these novel concepts with mixtures of ideal gases, and isothermal reactive damage mechanics and viscoelasticity, as well as reactive thermoelasticity. This framework facilitates the analysis of reactive tissue biomechanics and physiological and biomedical engineering processes where temperature variations cannot be neglected.

Simultaneous Calculation of Chemical and Isotope Equilibria Using the GEOCHEQ_Isotope Software: Oxygen Isotopes

Abstract— The GEOCHEQ_Isotope software package, elaborated previously for modeling chemical and carbon isotope equilibria in hydrothermal and hydrogeochemical systems by minimizing the Gibbs energy, is extended to the simultaneous calculation of carbon and oxygen isotopic effects. Similar to what was done for carbon, the β-factor formalism was used to develop algorithms and a database for calculating the isotopic effects of oxygen. According to the developed algorithm, the Gibbs energy of formation of a rare isotopologue, G*(P, T), is calculated through the Gibbs energy of formation of the main isotopologue, the value of the β18O factor of this substance, and the mass ratio of the rare (18O) and main (16O) isotopes. The isotope mixture is assumed to be ideal. The temperature dependence of the β-factor is unified as a polynomial in reciprocal absolute temperature. Necessary information on oxygen isotope equilibria involving important geochemical compounds was critically analyzed, and the available data were reconciled and modified. The temperature dependences of the β18O-factors were correspondingly optimized. The thermodynamic database was updated by adding information on the temperature dependence of β18O-factors specified by polynomial coefficients for each substance. The usage of the GEOCHEQ_Isotope software package and the corresponding database is demonstrated by modeling the dependence of oxygen and carbon isotope fractionation factors on the acidity of the solution (pH) in a carbonate hydrothermal system. The simulation results are in a good agreement with experimental data available from the literature. The enrichment of dissolved carbonates in the 18O heavy oxygen isotope relative to water decreases with increasing pH of the system. At the same time, a pH increase results in a decrease in the negative carbon isotope shift between calcite and dissolved carbonates. At high pH values (~11), the isotope shift inversion and the enrichment of the dissolved carbonate in the heavy carbon isotope relative to calcite are predicted.

Synthesis Method and Thermodynamic Characteristics of Anode Material Li3FeN2 for Application in Lithium-Ion Batteries

Li3FeN2 material was synthesized by two-step solid-state method from Li3N (adiabatic camera) and FeN2 (tube furnace) powders. Phase investigation of Li3N, FeN2 and Li3FeN2 were carried out. Discharge capacity of Li3FeN2 is 343 mAh g-1, that is about 44.7% of theoretic capacity. The molar heat capacity of Li3FeN2 at constant pressure in the temperature range 298-900 K should be calculated as Cp,m = 77,831 + 0,130 × T – 6,289 × T-2, where T is absolute temperature, . Thermodynamic characteristics of Li3FeN2 were determined as next: entropy S0298 = 116.2 J mol-1 K-1, molar enthalpy of dissolution ΔdHLFN = ˗ 206,537 ± 2,8 kJ mol−1, the standard enthalpy of formation ΔfH0 = ˗ 291.331 ± 5.7 kJ mol−1, entropy S0298 = 113.2 J mol-1 K-1 (Neumann-Kopp rule) and 116.2 J mol-1 K-1 (W.Herz rule), the standard Gibbs free energy of formation ∆f G0298 = ˗276,7 kJ mol-1.

Thermodynamical study of (CaGa2S4)x(BaGa2S4)1−x solid solutions

The solid solutions of [Formula: see text] were synthesized by solid-phase reactions from powder components of CaS, BaS, and Ga2S3. The temperature-concentration dependences of the Gibbs free energy of formation of [Formula: see text] solid solutions from ternary compounds and phase diagrams of the CaGa2S4–BaGa2S4 were determined by a calculation method. It was revealed that continuous solid solutions are formed in these systems. The spinodal decomposition of [Formula: see text] solid solutions into two phases is predicted at ordinary temperatures.

Sorption of molecular hydrogen on the graphene-like matrix doped by N- and B-atoms

The regularities of interaction of hydrogen molecules with graphene-like planes, where two carbon atoms are replaced by nitrogen or boron atoms, have been studied by the methods of quantum chemistry (DFT, B3LYP, 6-31G**). To take into account the dispersion contributions to the energy of formation of intermolecular complexes that occur during the formation of adsorption supramolecular structures, Grimme’ dispersion correction is used - D3. To study the effect of the size of a graphene-like cluster on the energy of molecular hydrogen chemisorption, polyaromatic molecules (PAM) are used of pyrene, coronene and that consisting of 54 carbon atoms, as well as their nitrogen- and boron-containing analogues where N- and B-atoms are placed in a para-position relative to each other, in the so-called piperazine configuration. The insertion of a heteroatom changes the structure of the transition state and the mechanism of chemisorption. An analysis of the results of quantum chemical calculations showed the highest exothermic dissociative adsorption of the H2 molecule on B-containing graphene-like ones. For N-containing PAM, the exothermicity of the mentioned reaction is somewhat lower, for it a possibility of desorption of atomic hydrogen desorption the surface of the latter with subsequent recombination in the gas phase has been also shown. At the same time, for models of pure graphene-like layer, the data obtained indicate the impossibility of chemisorption of molecular hydrogen. Without a complete analysis of the results for all the possible locations of the pair of hydrogen atoms (formed due to dissociation of the H2 molecule) bound by nitrogen-containing polyaromatic molecules, it can be noted that the dissociative chemisorption of the H2 molecule, regardless of the nature of heteroatom in the PAM, is thermodynamically more probable at the periphery of the model molecules than that in their centers.

Isomers of (L)-Diiodotyrosine - A DFT Treatise

(L)-Diiodotyrosine isomers are considered within the realm of density functional theory at the level of B3LYP/6-311+G(d,p). Their zwitter ionic forms are considered as well. All the structures are electronically stable, have exothermic heat of formation and favorable Gibbs free energy of formation values. Within the limitations of the method the zwitter ionic forms are not different from the corresponding parent structures in the vacuum conditions and no hydrogen bonding seems to exist between the NH2 and COOH groups. Some structural, quantum chemical and spectral data have been collected and discussed.

Interaction of 1,1-Diamino-2,2-Dinitroethylene with Aluminum and Gallium Admixture - DFT Treatment

Interaction of 1,1-diamino-2,2-dinitroethylene with nAl+mGa (n,m:1,2) admixture has been investigated within the constraints of density functional theory at the level of UB3LYP/6-311++G(d,p). Various multiplicity states arise for the composites due to the open-shell ground state electronic configurations of Al and Ga atoms. The composites are electronically stable, thermodynamically exothermic and have favorable Gibbs’ free energy of formation values. Various quantum chemical properties have been obtained and discussed. The calculated UV-VIS spectra indicate that some of the composites are infrared absorbing systems beyond 700 nm.