Determination of the Standard Free Energy of Formation of Cuprous Sulfide at 300°C

Wagner, Jeff; Wagner, Carl

doi:10.1149/1.2428637

Cited by 70 publications

(59 citation statements)

References 7 publications

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“…This formula modifies the coefficient K in the equation originally proposed for spherical precipitates, which was developed by Greenwood [47], Lifshitz and Slyozov [48], and Wagner [49] (known as GLSW or LSW theory). Eq.…”

Section: Time Dependence-isothermal Heat Treatmentsmentioning

confidence: 99%

Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

et al. 2011

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Section: Time Dependence-isothermal Heat Treatmentsmentioning

confidence: 99%

Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

et al. 2011

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“…2 using the Nernst-Einstein relationship D -= aRT/cq 2 [5] and from the tracer diffusion studies of Yao and Kummer (1), are compared in Fig. 8.…”

Section: Mechanism Of Di~usion Of Silver In Beta Alumina-mentioning

confidence: 99%

Transport Properties of Silver Beta Alumina

Whittingham¹,

Huggins²

1971

J. Electrochem. Soc.

153

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The total electrical conductivity and the electronic conductivity in silver beta alumina have been determined between 23 ~ and 800~ over a wide range of oxygen partial pressure using a-c and d-c techniques. The ionic transference number was found to be very close to unity under all conditions. Comparison of these measurements with tracer diffusion studies shows that the diffusion of silver ions takes place by an interstitialey mechanism.Previously reported measurements (1-3) of the ionic conductivity and the diffusion coefficient of monovalent ions, M, in materials of the beta alumina structure, represented by the general formula MAlllO~7, have indicated that this phase might prove to be very useful as a solid electrolyte or transducer element in electrochemical cells.In order to evaluate materials for such purposes, however, knowledge must be obtained about the transference numbers of both ionic and electronic species as well as the total electrical conductivity over broad ranges of temperature and other thermodynamic variables. Widely useful materials should have low values of electronic conductivity and relatively rapid ionic transport under conditions whereby they might be applied. It is not enough to have this information for only a limited set of experimental circumstances.Information concerning the electrical conductivity of single crystals of beta alumina containing silver as the monovalent cation is presented in this paper. In this case simple (silver) metallic electrodes could be used which are essentially reversible to both M ions and electronic species over wide ranges of both temperature and oxygen partial pressure. In addition to standard a-c and d-c measurements, the Wagner asymmetric polarization technique (4-8) was used to investigate the electron and hole conductivities. Experiments were conducted from 23 ~ to 800~ and over a range of oxygen partial pressures, from 0.2 to 10 -24 atm. Experimental and ResultsPreparation and analysis of samples.--Batches of single crystals of sodium beta alumina were obtained from the Carborundum Company, and crystals which were optically free of a second phase were selected for study. Samples of silver beta alumina were prepared from the sodium beta alumina starting material by immersion in pure silver nitrate at a temperature slightly above its melting point (1). However, in this case, elemental silver was also present in the bath, so that the silver activity was maintained at unity. A 1 On leave from Stanford University.Electrochemical Society Active Member. Key words: silver diffusion in beta alumina, electrical transport, solid electrolyte.process of solid-state ion exchange takes place by chemical diffusion among the monovalent cations in the beta alumina structure, with the sodium ions being replaced by silver ions. After equilibration (about 24 hr) the samples were removed, washed, and weighed to indicate the amount of exchange, and replaced in a fresh batch of silver nitrate so that the sodium activity was again reduced to a very low value. This ...

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“…25,26 Figure 5a shows the time dependence of the polarization/depolarization cell voltage for the freeze-cast sample (5 • C/min), with applied constant current (galvanostatic mode). The polarization/depolarization voltage (t > T c ), depends on time as follows: [27][28][29] [2] Where i p is the applied current; L is the sample thickness; σ, σ el , σ ion are the total, electronic and ionic conductivities respectively and T c is the characteristic -also called relaxation-time Equation 2 can be expressed as:…”

Section: Resultsmentioning

confidence: 99%

Impact of Pore Tortuosity on Electrode Kinetics in Lithium Battery Electrodes: Study in Directionally Freeze-Cast LiNi_0.8Co_0.15Al_0.05O₂(NCA)

Delattre

Amin

Sander

et al. 2018

J. Electrochem. Soc.

120

109

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The prevailing electrode fabrication method for lithium-ion battery electrodes includes calendering at high pressures to densify the electrode and promote adhesion to the metal current collector. However, this process increases the tortuosity of the pore network in the primary transport direction and imposes severe tradeoffs between electrode thickness and rate capability. With the aim of understanding the impact of pore tortuosity on electrode kinetics, and enabling cell designs with thicker electrodes and improved cost and energy density, we use here freeze-casting, a shaping technique able to produce low-tortuosity structures using ice crystals as a pore-forming agent, to fabricate LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathodes with controlled, aligned porosity. Electrode tortuosity is characterized using two complementary methods, X-ray tomography combined with thermal diffusion simulations, and electrochemical transport measurements. The results allow comparison across a wide range of microstructures, and highlight the large impact of a relatively small numerical change in tortuosity on electrode kinetics. Under galvanostatic discharge, optimized microstructures show a three-to fourfold increase in area-specific capacity compared to typical Li-ion composite electrodes. Hybrid pulse power characterization (HPPC) demonstrates improved power capability, while dynamic stress tests (DST) shows that an area-specific area capacity corresponding to 91% of the NCA galvanostatic C/10 capacity could be reached. With the ever-increasing demand for mobile applications and the growing concern for the replacement of fossil fuels, alternative energy storage has become an increasingly pressing but still unsolved problem.1-3 Because of their unequalled combination of high energy and power density, lightweight design and excellent lifespan, lithiumion batteries are to date the technology of choice for portable electrochemical storage, powering applications such as electronic devices, power tools and hybrid/full electric vehicles. The prevailing electrode fabrication method for lithium-ion battery electrodes includes high pressure calendering of electrode formulations that include active lithium materials, organic binder and conductive additives, in order to densify the electrode and promote adhesion to the metal current collector. However, this process also increases the tortuosity of the pore network in the primary transport direction. In practice, to meet operational C-rates desired, and production throughput objectives, the thicknesses of commercial electrodes are restricted to less than ∼100 μm. Beyond this value, ion transport becomes a limiting factor and the accessible specific capacity starts to drop dramatically. 4 With the aim of increasing cell energy density and decreasing cost by building thicker electrodes, several strategies to reduce pore tortuosity by aligning the porosity in the direction normal to the current collector have been proposed. Bae et al.5 demonstrated through modeling and experiments that a dual-sc...

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Determination of the Standard Free Energy of Formation of Cuprous Sulfide at 300°C

Cited by 70 publications

References 7 publications

Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

Transport Properties of Silver Beta Alumina

Impact of Pore Tortuosity on Electrode Kinetics in Lithium Battery Electrodes: Study in Directionally Freeze-Cast LiNi_0.8Co_0.15Al_0.05O₂(NCA)

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Determination of the Standard Free Energy of Formation of Cuprous Sulfide at 300°C

Cited by 70 publications

References 7 publications

Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

Transport Properties of Silver Beta Alumina

Impact of Pore Tortuosity on Electrode Kinetics in Lithium Battery Electrodes: Study in Directionally Freeze-Cast LiNi0.8Co0.15Al0.05O2(NCA)

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Impact of Pore Tortuosity on Electrode Kinetics in Lithium Battery Electrodes: Study in Directionally Freeze-Cast LiNi_0.8Co_0.15Al_0.05O₂(NCA)