Model Of Electrolyte Solutions Research Articles

Modified nonelectrolyte Wilson-NRF: A new model for strong and weak electrolyte solutions

In this work, the nonelectrolyte Wilson-NRF model has been modified and a new model composed of a modified nonelectrolyte Wilson-NRF (m-Wilson-NRF) equation and the Pitzer-Debye-Hückel equation has been used to represent thermodynamics properties of strong and weak electrolyte solutions. In the first attempt, the present model is applied to correlate activity coefficients of various aqueous solutions of salt at 25 °C and 1 bar as strong electrolyte systems. Also, the osmotic coefficients of the binary and ternary electrolyte solutions are well predicted using the present model. In following, as weak electrolyte systems the solubility of acid gases such as CO2 and H2S in aqueous N-methyldiethanolamine (MDEA) solutions have been represented by the new model in a wide range of temperature, MDEA concentration and partial pressures of acid gases. Comparisons between the results of the new model with other electrolyte models confirm the good capability of the new equation for strong and weak electrolyte solutions.

Generalized Quasi-Random Lattice model for electrolyte solutions: Mean activity and osmotic coefficients, apparent and partial molal volumes and enthalpies

Electrolytes are the subject of a vast number of theoretical and experimental investigations concerned with a variety of modern applications. The modeling of thermodynamic properties of ionic solutions is thus a fundamental research topic that has been supported in many ways for many decades. There is however still a lack of models that are truly predictive over wide ranges of concentration, temperature and pressure conditions.In this article, the Quasi-Random Lattice (QRL) model is presented in a generalized form that allows for evaluating relevant thermodynamic properties of binary electrolyte solutions. The semi-predictive character of the model yields a powerful and competitive representation of electrolyte data over well defined concentration ranges. The additional experimental information to support the generalized version of QRL is very modest compared to the number of data points typically used in regression techniques for best-fit purposes. The thermodynamic consistency of the improved QRL model is demonstrated by the level of agreement with experimental data concerning mean activity and osmotic coefficients, apparent and partial molal volumes and enthalpies, for a variety of aqueous 1:1, 2:1, and 3:1 electrolytes.

Thermodynamics of primitive model electrolytes in the symmetric and modified Poisson-Boltzmann theories. A comparative study with Monte Carlo simulations

Osmotic coefficients, individual and mean activity coefficients of primitive model electrolyte solutions are computed at different molar concentrations using the symmetric Poisson-Boltzmann and modified Poisson-Boltzmann theories. The theoretical results are compared with an extensive series of Monte Carlo simulation data obtained by Abbas et al. [Fluid Phase Equilib., 2007, 260, 233; J. Phys. Chem. B, 2009, 113, 5905]. The agreement between modified Poisson-Boltzmann predictions with the "exact" simulation results is almost quantitative for monovalent salts, while being semi-quantitative or better for higher and multivalent salts. The symmetric Poisson-Boltzmann results, on the other hand, are very good for monovalent systems but tend to deviate at higher concentrations and/or for multi-valent systems. Some recent experimental values for activity coefficients of HCl solution (individual and mean activities) and NaCl solution (mean activity only) have also been compared with the symmetric and modified Poisson-Boltzmann theories, and with the Monte Carlo simulations.

Thermochemical Properties of the Dissolution of Rubidium d-Gluconate Rb[d-C6H11O7]2(s) in Aqueous Solutions

A novel coordination compound rubidium d-gluconate Rb[d-C6H11O7](s) has been synthesized and characterized by chemical analysis, elemental analysis, and X-ray diffraction. Single-crystal X-ray analysis reveals that the crystal is monoclinic with space group P21 and Z = 2. Also, the d-gluconate anion in Rb[d-C6H11O7](s) has a bent-chain conformation, in which the carbon atoms of the anion form two approximate planes. The compound exhibits an obvious chelation of the d-gluconate anions to the rubidum(I) cation and the cation is seven-coordinated to all seven oxygen atoms. The lattice potential energy and ionic volume of the anion d-\( {\text{C}}_{ 6} {\text{H}}_{ 1 1} {\text{O}}_{7}^{ - } \) were obtained to be UPOT = 484.23 kJ·mol−1 and V− = 0.2004 nm3 from crystallographic data. Molar enthalpies of dissolution of Rb[d-C6H11O7](s) in double-distilled water at various molalities were measured by use of an isoperibol solution–reaction calorimeter at T = 298.15 K. According to Pitzer’s electrolyte solution model, the molar enthalpy of dissolution of the title compound at infinite dilution was determined to be \( \Delta_{\text{s}} H_{\text{m}}^{\infty } = (29.76 \pm 0.72){\text{ kJ}}{\cdot}{\text{mol}}^{ - 1} \). The values of the apparent relative molar enthalpies (\( ^{\phi } L_{{}} \)) of the title compound and relative partial molar enthalpies (\( \bar{L}_{2} \) and \( \bar{L}_{1} \)) of the solute and the solvent at different concentrations were derived from the experimental enthalpies of dissolution of the compound. Furthermore, the molar enthalpy of hydration of the anion d-\( {\text{C}}_{ 6} {\text{H}}_{ 1 1} {\text{O}}_{7}^{ - } \) was calculated to be ΔH− = − (166.4 ± 2.7) kJ·mol−1 by use of a thermochemical cycle.

On the application of the associative mean spherical approximation to the ion-dipole model for electrolyte solutions

The solution of the associative mean spherical approximation for the ion-dipole model of an electrolyte solution is simplified and analyzed. It is shown that the description of this model can be reduced to a system of three coupled non-linear algebraic equations for ion-ion, ion-dipole and dipole-dipole energy parameters J0, b10 and b2. A possibility of introducing ionic and dipolar scaling parameters ΓB and λ is discussed. Analytical expressions for the thermodynamic functions and solvent static dielectric permittivity are presented.

The Debye-Hückel theory and its importance in modeling electrolyte solutions

A colleague at the Technical University of Denmark has often stated: “Life is too short for electrolytes”. Another well-known scientist in the field of molecular simulation has recently said during an international Thermodynamics conference: “All my life I have tried to keep myself away from water and electrolytes”. Sadly, what these statements correctly imply is that there are far too many unclear questions and concepts in electrolyte thermodynamics, and associated difficulties in modeling electrolyte solutions. In this work, we attempt to shed some light on some important concepts and misconceptions in electrolyte thermodynamics associated with the development of electrolyte equations of state, with emphasis on those based on the Debye-Hückel theory. Detailed mathematics is needed for some of the derivations but for brevity and in order to emphasize the principles rather than the derivations, the latter are omitted. We first discuss the peculiarities of electrolyte thermodynamics and associated modeling and continue with a literature review of equations of state for electrolyte solutions. Next we will provide a modern derivation of the Debye-Hückel and Born equations and discuss their assumptions in detail to answer some of the confusion that exists in current literature on the applicability ranges and show how the different versions of the Debye-Hückel and Born models are related. A discussion and outlook section conclude this review. Several of the statements in this work challenge “accepted beliefs” in electrolyte thermodynamics and, while we believe that this challenge is justified, we hope that a useful debate can result in improved and predictive thermodynamic models for electrolyte solutions.

Correlating vapour-liquid equilibria of binary HI + H2O mixtures using Pitzer’s model of electrolyte solutions

Abstract The need to produce Hydrogen in an environmentally friendly manner has increased as the transportation industry has started to employ cleaner sources of energy. One of the cleaner ways to produce H2, is to use the Bunsen S-I cycle. This includes the separation of the H2 from an ionic mixture of Hydrogen Iodide and water using distillation. In this work, the Pitzer’s model for electrolyte solutions has been employed to represent the vapour-liquid equilibrium (VLE) of the binary system of HI and H2O. The activity coefficient (γ) is calculated from the equation which indicated the non-ideal nature of the system and aided the calculation of the vapour phase mole fraction. The experimental VLE data was obtained from a recirculating still at 101.3 kPa pressure for the binary system. This experimental data and data from literature was used to estimate the parameters of the Pitzer’s model to represent the activity coefficient of HI in this mixture. These optimized parameters could explain all the variations in the data with more that 90% accuracy for most of the data, with an average standard deviation of about 0.04. Furthermore, the temperature dependent form of the Pitzer’s equation was used to predict the VLE data at higher pressures of 3 and 5.7 bars and higher temperature conditions.

Coarse-Grained Model of the Dynamics of Electrolyte Solutions.

Ion-specific solvation has fundamental implications in biochemistry, and the thermodynamics and dynamics of aqueous salt solutions have correspondingly been investigated intensively. Nonetheless, there are fundamental unresolved issues in modeling the dynamics of aqueous salt solutions and the related problem of polymers dissolved in these solutions. In particular, experiments show that the self-diffusion coefficient, D, of water molecules in electrolyte solutions can be either enhanced or suppressed by particular salts having the same valence where the observed changes correlate with the Hofmeister series governing the relative solubility of proteins and water-soluble polymers in the same salt solutions. Recent studies have demonstrated that common atomistic models of aqueous electrolyte solutions completely fail to reproduce this basic phenomenon. Drawing on similar trends observed in the field of polymer nanocomposites, we propose a coarse-grained model of aqueous electrolyte solutions that captures the observed trends and that offers physical insight into the influence of salt on the thermodynamic and dynamic properties of electrolyte solutions.

Transport Limitations in Binary Electrolytes: The Temperature Dependence of the Electrolyte Transport Parameters

The ion-transport model for concentrated electrolyte solutions introduced by Newman and Thomas-Alyea1is frequently used for numerical simulations of battery systems and depends on three ion transport parameters: the conductivity, the transference number and the binary diffusion coefficient. In addition, the thermodynamic factor, which is derived from the mean molar activity coefficient, is required for the correct description of the thermodynamic behavior of a binary electrolyte solution. The resistive ion transport of the binary electrolyte in a lithium ion battery causes the formation of temperature gradients, especially in large format cells. To understand the influence of local temperature inhomogeneity on, e.g., the aging of the cell, it is necessary to have a profound understanding of the temperature dependence of the ion transport parameters. While a vast spectrum of physico-chemical parameters can be found in the literature only few publications study their temperature dependence, e.g., Valoen and Reimers2. In addition, some of the parameters are often fitted to match experimental performance data and may thus be fitting parameters rather than intrinsic physico-chemical parameters with predictive capability. We present the results of our temperature dependent study of the ionic transport parameters from commonly used lithium electrolytes by using a new method to determine the thermodynamic factor3and combining it with concentration cell experiments to determine transference numbers. Using common polarization cell experiments, we additionally determine diffusion coefficients while conductivities are measured using turn-key equipment. We chose common battery electrolytes, e.g., LiPF6 in EC:EMC (3:7 w:w) and LiPF6 in EC:DMC (1:1 w:w) for our analysis. Exemplarily shown in Figure 1. is the relative temperature dependence of the transference number, thermodynamic factor and the diffusion coefficient for a 0.1 M, 1 M and a 2 M LiClO4in EC:DEC (1:1 w:w) electrolyte. Our results allow us to use numerical experiments to study the temperature dependent transport limitations in binary electrolyte and their influence on the cell performance. Adaption of our transport parameters in Newman type battery models will enhance numerical predictions. The study of temperature variations in large format cells might help to understand the observed, spatially dependent aging in, e.g., cylindrical cells and thereby enables the design and improvement of better lithium ion batteries in the future. Figure 1. Relative change of transference number, binary diffusion coefficient and thermodynamic factor versus their 20°C value a LiClO4in EC:DEC (1:1 w:w) electrolyte at 0.1, 1 and 2 M concentrations.

Transport Limitations in Binary Electrolytes: EC-Free Solvents and NaPF6 Vs. LiPF6 Salts

For numerical simulations of battery systems, the ion-transport model for concentrated electrolyte solutions introduced by Newman and Thomas-Alyea1is frequently used and depends on three ion transport parameters: the conductivity, the transference number and the binary diffusion coefficient. In addition, the thermodynamic factor which is derived from the mean molar activity coefficient is required for the correct description of the thermodynamic behavior of a binary electrolyte solution. A vast spectrum of physico-chemical parameters can be found in the literature (e.g., Valoen and Reimers2), but since the investigated electrolytes and the experimental techniques differ from study to study, it is difficult to find a consistent parameter set for a given electrolyte. In addition, some of the parameters are often fitted to match experimental performance data and may thus be fitting parameters rather than intrinsic physico-chemical parameters with predictive capability. In our work, a new method to determine the thermodynamic factor3is combined with con-centration cell experiments to determine trans-ference numbers. Using common polarization cell experiments, we additionally determine diffusion coefficients while conductivities are measured using turn-key equipment. Our main objective is to analyze the limitations of new, emerging battery chemistries, e.g., EC-free electrolytes4 for lithium ion batteries or electrolytes for sodium batteries,5 and compare their electro-chemical transport properties to a common solution, e.g., LiPF6 in EC:EMC (3:7 w:w). Exemplarily shown is the comparison of the ionic conductivity for a NaPF6 and a LiPF6electrolyte in the same solvent, EC:DEC (1:1 v:v). To compare the obtained transport parameters and to depict their impact on the cell performance, we incorporate the obtained functional descriptions in an arbitrarily chosen graphite-NMC cell model. We will show which fraction of the cell overpotential is caused by the electrolyte and analyze its effect on the rate performance of the cell. Our research will help to understand the limitation caused by concentration overpotentials in current lithium ion battery systems. Adaption of our transport parameters in Newman type battery models will enhance numerical predictions. Analysis of the type of solvent and salt will help to understand the sources for ionic transport limitations and thereby helps improving future battery electrolyte solutions. Figure 1: Conductivity of NaPF6 and LiPF6 from 0.1 M to 2 M in EC:DEC (1:1 vol.) at 25°C.

Thermochemical Properties of Dissolution of Nicotinic Acid C6H5NO2(s) in Aqueous Solution

Nicotinic acid (also known as niacin) was recrystallized from anhydrous ethanol. X-ray crystallography was applied to characterize its crystal structure. The crystal belongs to the monoclinic system, space group P2(1)/c. The crystal cell parameters are a = 0.71401(4) nm, b = 1.16195(7) nm, c = 0.71974(6) nm, α = 90°, β = 113.514(3)°, γ = 90° and Z = 4. Molar enthalpies of dissolution of the compound, at different molalities m/(mol·kg−1) were measured with an isoperibol solution–reaction calorimeter at T = 298.15 K. The molar enthalpy of solution at infinite dilution was calculated, according to Pitzer’s electrolyte solution model and found to be \( \Delta_{\text{sol}} H_{m}^{\infty } = ( 2 7. 3 \pm 0. 2) \) kJ·mol−1 and Pitzer’s parameters (\( \beta_{{\text{MX}}}^{{\text{(0)}L}} \), \( \beta_{{\text{MX}}}^{{\text{(1)}L}} \) and \( C_{{\text{MX}}}^{\phi L} \)) were obtained. The values of apparent relative molar enthalpies (\( {}^{\phi }L \)) and relative partial molar enthalpies (\( \overline{{L_{2} }} \) and \( \overline{{L_{1} }} \)) of the solute and the solvent at different molalities were derived from the experimental enthalpy of dissolution values of the compound. Also, the standard molar enthalpy of formation of the anion \( {\text{C}}_{ 6} {\text{H}}_{ 4} \text{NO}_{2}^{-} \) in aqueous solution was calculated to be \( {\Delta_{\text{f}}^{} H}_{\text{m}}^{\text{o}} ({\text{C}}_{ 6} {\text{H}}_{ 4} {\text{NO}}_{2}^{-} \text{,aq}) = - \left( {603.2 \pm 1.2} \right)\;{\text{kJ}}{\cdot}{\text{mol}}^{-1} \).

A molecular Debye-Hückel theory and its applications to electrolyte solutions: The size asymmetric case.

A molecular Debye-Hückel theory for electrolyte solutions with size asymmetry is developed, where the dielectric response of an electrolyte solution is described by a linear combination of Debye-Hückel-like response modes. As the size asymmetry of an electrolyte solution leads to a charge imbalanced border zone around a solute, the dielectric response to the solute is characterized by two types of charge sources, namely, a bare solute charge and a charge distribution due to size asymmetry. These two kinds of charge sources are screened by the solvent differently, our theory presents a method to calculate the mean electric potential as well as the electrostatic contributions to thermodynamic properties. The theory has been successfully applied to binary as well as multi-component primitive models of electrolyte solutions.

Modeling of systems with aqueous solutions of UO 2 2+ salts. Asymmetric model of excess thermodynamic functions, based on virial expansion of the Gibbs free energy of the solution, VD-AS

An asymmetric model of virial expansion of the Gibbs free energy of solution, VD-AS, was suggested. Partial and molar thermodynamic functions of UO2(ClO4)2–H2O, UO2Cl2–H2O, and UO2(NO3)2–H2O binary solutions at 25°C were calculated using this model. The calculations show that the solutions are characterized by different, sometimes extremely large, deviations from ideality. The suggested model is considerably more accurate and stable than the most widely used Pitzer’s model of electrolyte solutions.

Conductivity Sensor for Real‐time Monitoring of Magnesium Corrosion under Cell Culture Conditions

AbstractDue to its ability to biodegrade in an aqueous, chloride‐containing environment, magnesium (Mg) metal, pure or as an alloy, has attracted significant interest in biomaterials research for use in biodegradable implants for bone repair and other applications. However, the interactions between Mg metal and surrounding cells and tissues as the metal resorbs need to be studied extensively to ensure adequate biocompatibility for each intended application. Cell death can result from high local concentrations of the soluble resorption products, which include Mg ions (Mg2+), alloying products, increased pH and hydrogen. Because these products are primarily ionic, we tested whether a conductivity sensor could be used to monitor Mg degradation by detecting changes in ionic strength in real time, in three physiologically appropriate fluids (a sodium chloride solution, phosphate buffered saline and a cell culture medium maintained under the standard conditions used for mammalian cell culture). Here we demonstrate that an electrochemical conductivity sensor, in combination with a pH sensor, recorded very different patterns of real‐time changes in the ionic environment created by Mg immersion and degradation in the three model electrolyte solutions, over a 48‐hour time period.

Density functional theory of electrolyte solutions in slit-like nanopores I. The RFD/WCA approach extended to non-restricted primitive model

An extended reference fluid density approach/weighted correlation approximation (RFD/WCA) of density functional theory (DFT) is tested for the description of the non-restricted primitive model of electrolyte solutions in slit-like nanopores. The RFD/WCA approach of modeling size-asymmetric ions is validated by reproducing the density and electrostatic potential profiles of planar electrical double layer systems in the presence of mixtures of mono- and multivalent ions. The results from the DFT agree quite well with Monte Carlo simulations and satisfy the contact density sum rules of ionic fluid under a wide range of conditions. These findings suggest that a generic RFD/WCA approach can be formulated within the framework of the restricted and non-restricted primitive model to further investigate the swelling and ion exchange of clay minerals.

Theory of model electrolyte solutions: Assessing the short- and long-ranged contributions by molecular simulations

In this work, we conduct a comprehensive simulation study on Helmholtz energies for non-primitive model electrolyte solutions in order to assess fluid theories. Simulation data is obtained with two different methods. Using a new thermodynamic integration path, we calculate Helmholtz energy contributions arising from damped, short-ranged electrostatic pair potentials. The division of the potential into a damped, short-ranged and a long-ranged part using a complementary error function corresponds to the division of a standard Ewald sum. Additionally, we applied a standard thermodynamic integration method to obtain the full electrostatic contribution to the Helmholtz energy. We evaluate the analytical long-range contribution developed by Rodgers and Weeks [J. M. Rodgers and J. D. Weeks, J. Chem. Phys. 131, 244108 (2009)] and find excellent agreement to our simulation data for any damping parameter α*≥1.5 for liquid-like densities. Further, the simulation data is compared to a third order perturbation theory we recently presented. By analyzing the theory against results of molecular simulations we were able to introduce refinements to our theory, such as a rearranged Padé approximation. We show, however, that third order perturbation theory, despite these improvements, is only reliable for strongly damped potentials (α*<1) for ion-dipole as well as for purely dipolar fluids. This study shows that a perturbation theory of third order is insufficient for such systems.

Development of intermolecular potential models for electrolyte solutions using an electrolyte SAFT-VR Mie equation of state

ABSTRACTWe present a theoretical framework and parameterisation of intermolecular potentials for aqueous electrolyte solutions using the statistical associating fluid theory based on the Mie interaction potential (SAFT-VR Mie), coupled with the primitive, non-restricted mean-spherical approximation (MSA) for electrolytes. In common with other SAFT approaches, water is modelled as a spherical molecule with four off-centre association sites to represent the hydrogen-bonding interactions; the repulsive and dispersive interactions between the molecular cores are represented with a potential of the Mie (generalised Lennard-Jones) form. The ionic species are modelled as fully dissociated, and each ion is treated as spherical: Coulombic ion–ion interactions are included at the centre of a Mie core; the ion–water interactions are also modelled with a Mie potential without an explicit treatment of ion–dipole interaction. A Born contribution to the Helmholtz free energy of the system is included to account for the process of charging the ions in the aqueous dielectric medium. The parameterisation of the ion potential models is simplified by representing the ion–ion dispersive interaction energies with a modified version of the London theory for the unlike attractions. By combining the Shannon estimates of the size of the ionic species with the Born cavity size reported by Rashin and Honig, the parameterisation of the model is reduced to the determination of a single ion–solvent attractive interaction parameter. The resulting SAFT-VRE Mie parameter sets allow one to accurately reproduce the densities, vapour pressures, and osmotic coefficients for a broad variety of aqueous electrolyte solutions; the activity coefficients of the ions, which are not used in the parameterisation of the models, are also found to be in good agreement with the experimental data. The models are shown to be reliable beyond the molality range considered during parameter estimation. The inclusion of the Born free-energy contribution, together with appropriate estimates for the size of the ionic cavity, allows for accurate predictions of the Gibbs free energy of solvation of the ionic species considered. The solubility limits are also predicted for a number of salts; in cases where reliable reference data are available the predictions are in good agreement with experiment.

On the hydrophilicity of electrodes for capacitive energy extraction

The so-called Capmix technique for energy extraction is based on the cyclic expansion of electrical double layers to harvest dissipative energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the electrical potentials for the charging and discharging processes, which must be matched with the pore characteristics of the electrode materials. While a number of recent studies have examined the effects of the electrode pore size and geometry on the capacitive energy extraction processes, there is little knowledge on how the surface properties of the electrodes affect the thermodynamic efficiency. In this work, we investigate the Capmix processes using the classical density functional theory for a realistic model of electrolyte solutions. The theoretical predictions allow us to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different surface hydrophobicity. In agreement with recent experiments, we find that the thermodynamic efficiency can be much improved by using most hydrophilic electrodes.

Determination of Physico-Chemical Parameters for Simulation of Lithium Ion Batteries

For understanding of existing battery systems such as lithium-ion batteries and for the development of future battery systems, advanced numerical simulation tools are important. One beneficial aspect of computational methods is that they can provide insight into physical and chemical aspects, which sometimes cannot be probed by experimental methods. Accuracy and reliability are key issues for such numerical simulations and depend on appropriate physical models, boundary conditions, and accurately determined physico-chemical parameters1. For numerical simulations of battery systems, the ion-transport model for concentrated electrolyte solutions introduced by Newman and Thomas-Alyea is frequently used and depends on three ion transport parameters, namely the conductivity, the transference number and the binary diffusion coefficient. In addition to the transport parameters, the thermodynamic factor which is derived from the mean molar activity coefficient is required for the correct description of the thermodynamic behavior of a binary electrolyte solution. Since the microscopic geometry of actually used porous electrodes and separators are largely unknown, a homogenization approach is applied for the macroscopic description of porous media. In this case, the influence of the microstructure on the macroscopic behavior is modelled by additional geometric parameters such as the porosity ε and the tortuosity τ. For an accurate description of the interface reactions the intercalation and deintercalation kinetics have to be known, often described by a Butler-Volmer behavior. Lastly solid state diffusion of lithium ions within the active materials may limit the battery performance, especially at high charge and discharge currents. A vast spectrum of physico-chemical parameters can be found in the literature (e.g., Valoen and Reimers2), but since the investigated electrolytes and the experimental techniques differ from study to study, it is difficult to find a consistent parameter set for a given electrolyte. In addition, some of the parameters are often fitted to match experimental performance data and may thus be fitting parameters rather than intrinsic physico-chemical parameters with predictive capability. We will present an overview of the necessary physico-chemical parameters for simulation of lithium ion battery performance and will show methods by which they can be measured rigorously. For example, novel methods will be shown with which one can determine transport, thermodynamic and geometrical properties like for instance the transference number, the thermodynamic factor and the separator and electrode tortuosity3-5. Figure 1 exemplarily shows one of those results, namely the determination of electrode tortuosities based on impedance spectroscopy measurements in symmetrical cells. Our concentration and temperature dependent studies of physico-chemical parameters as well as the methodology for their unambiguous deter-mination will allow for an improved correlation between lithium ion battery experiments and simulations. More importantly, the use of intrinsic physico-chemical paramters will enable predictive simulations rather than data fitting models, which helps in understanding as well as predicting present and future lithium ion battery technologies. Figure 1: Comparison of determined tortuosities for different electrodes at porosities between 30% and 35% and comparison with the tortuosity obtained by the commonly used Bruggeman estimate (τ=ε -0.5). Acknowledgements We gratefully acknowledge the funding by the Bavarian Ministry of Economic Affairs and Media, Energy, and Technology for its financial support under the auspices of the EEBatt project.

Chemical potential of model electrolyte solutions consisting of hard sphere ions and hard dipoles from molecular simulations

Mixtures of charged and dipolar hard spheres are important models for electrolyte solutions, in particular for developing molecular-based fluid theories. This study presents data for the ionic chemical potential from Monte Carlo simulations for mixtures where charged and dipolar hard spheres have the same diameter. Earlier simulation studies of this model focus on Helmholtz energy and internal energy. The chemical potential is a sensitive quantity for assessing and refining fluid theories and it is the determining quantity for calculating phase equilibria. We provide chemical potentials for different dipole moments, ionic charges, ion concentrations, and liquid-like densities. The data is obtained by two methods, a multistage sampling scheme as well as expanded ensemble transition matrix method. A system size study shows that standard Ewald summation is a valid method for calculating the chemical potential from molecular simulations and we ensure that finite size effects are negligible for the presented data.