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Determination of the Kinetic Parameters of Mixed‐Conducting Electrodes and Application to the System Li3Sb
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1977
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EngineeringElectrode-electrolyte InterfaceChemistryChemical EngineeringMaterials ScienceElectrical EngineeringBattery Electrode MaterialsComposition GradientsLithium-ion BatteryBattery AdditivesLithium-ion BatteriesKinetic ParametersEnergy StorageChemical Diffusion CoefficientSolid-state BatteryElectrochemical ProcessElectrochemistryElectric BatteryLi-ion Battery MaterialsCathode MaterialsElectrochemical Energy StorageBatteriesSystem Li3sbMixed‐conducting ElectrodesChemical Kinetics
The authors present a galvanostatic intermittent titration technique (GITT) that combines transient and steady‑state measurements to extract kinetic and thermodynamic properties of solid mixed‑conducting electrodes. The technique derives chemical and component diffusion coefficients, partial conductivity, mobility, thermodynamic enhancement factor, and parabolic rate constant as functions of stoichiometry, and analyzes factors governing composition‑gradient equilibration. When applied to Li₃Sb, the method reveals a high chemical diffusion coefficient at 360 °C driven by a large thermodynamic enhancement factor, a comparatively low lithium diffusion coefficient, and significant partial conductivity and mobility, indicating the material’s potential for secondary batteries.
An electrochemical galvanostatic intermittent titration technique (GITT) is described which combines both transient and steady‐state measurements to obtain kinetic properties of solid mixed‐conducting electrodes, as well as thermodynamic data. The derivation of quantities such as the chemical and component diffusion coefficients, the partial conductivity, the mobility, the thermodynamic enhancement factor, and the parabolic rate constant as a function of stoichiometry is presented. A description of the factors governing the equilibration of composition gradients in such phases is included. The technique is applied to the determination of the kinetic parameters of the compound which has a narrow composition range. For the chemical diffusion coefficient is at 360°C. This value is quite high, due to a large thermodynamic enhancement factor of . The lithium component diffusion coefficient is comparatively small at this composition, . The partial conductivity and electrical mobility of lithium are and , respectively, at the same stoichiometry and temperature. Because of the very large values of the chemical diffusion coefficient and the fact that 3 moles of lithium can react per mole of antimony, this system may be of interest for use in new types of secondary batteries.