Thermal conductivity of the thermoelectric layered cobalt oxides measured by the Harman method

Satake, Akiharu; Tanaka, Hiroe; Ohkawa, T.; Fujii, Toshitsugu; Terasaki, Ichiro

doi:10.1063/1.1753070

Cited by 87 publications

(53 citation statements)

References 21 publications

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“…In Ref. 54 56,57 These experiments report the intrinsic thermal conductivities of these crystals, for instance for NaCoO 2 , to vary from 5-15 W/mK with varying intercalation of Na.…”

Section: Battery Electrode Microstructures-mentioning

confidence: 99%

Bruggeman's Exponents for Effective Thermal Conductivity of Lithium-Ion Battery Electrodes

Vadakkepatt

Trembacki

Mathur

et al. 2015

J. Electrochem. Soc.

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Simulations of lithium-ion battery cells are usually performed with volume averaging methods that employ effective transport properties. Bruggeman's model, which is widely used to determine these effective properties, is primarily based on the volume fraction of porous electrodes. It does not consider actual particle shape, size or the topology of constituent phases; these play a crucial role in determining effective transport. In this paper, a general derivation of the effective thermal conductivity of multiphase materials, which can be correlated with these factors, is derived using the volume averaging technique. Three-dimensional finite volume meshes of fully-resolved lithium-ion battery cathode microstructures are reconstructed from scanned images. Effective volume averaged thermal conductivity is then determined from numerical analysis of thermal transport on these meshes. It is shown that the Bruggeman model for effective thermal conductivity must be recalibrated to fit the effective thermal conductivity computed from these detailed simulations. The relevance of these results to effective transport properties typically employed in electrochemical simulations is presented. Commonly used theories for effective thermal transport in composites are evaluated for comparison. Furthermore, it is shown that Bruggeman's exponents yield an important quantitative measure, the connectivity, to characterize the physical path for transport through the underlying phases. The importance of lithium-ion batteries is now well recognized in light of the global energy crisis, global warming and the need for efficient and inexpensive energy storage options.1,2 Battery physics encompass thermodynamics, electrochemistry, material science, transport phenomena and solid mechanics, and span multiple length and time scales.3 Realistic modeling of batteries across these disparate physics and scales is critical for their effective and safe commercialization. 4 Research in lithium-ion batteries has been primarily driven by the need to develop cathode, anode and electrolyte materials that deliver high potential and capacity. 5,6 On the cell level, the battery consists of a porous composite anode and cathode filled with an electrolyte and separated by a separator. Typically, the thickness of such a sandwich is hundreds of microns, while lateral dimensions are of the order of centimeters. Lithium ions shuttle between cathode and anode during charge and discharge. Active cathode particles (for e.g. LiCoO 2 , LiMn 2 O 4 , LiFePO 4 ), which form the key constituent of batteries, are lithium insertion compounds and have high lithium ion conductivity. These active particles are spatially dispersed and held together by binder (such as polyvinylidene fluoride [PVDF]), while the electrolyte resides in the pores, wetting the active particles, and facilitating transport of lithium ions. The electronic conductivity of these active materials is generally low compared to lithium ion conductivity. Therefore additives like carbon particles are dispersed ...

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“…In Ref. 54 56,57 These experiments report the intrinsic thermal conductivities of these crystals, for instance for NaCoO 2 , to vary from 5-15 W/mK with varying intercalation of Na.…”

Section: Battery Electrode Microstructures-mentioning

confidence: 99%

Bruggeman's Exponents for Effective Thermal Conductivity of Lithium-Ion Battery Electrodes

Vadakkepatt

Trembacki

Mathur

et al. 2015

J. Electrochem. Soc.

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“…The FK model that describes the effects of a typical on-site potential has been studied extensively [2]. As we mentioned in the Introduction to paper Ⅰ, one of our motivations for studying this system was that very low lattice-thermalconductivity was found experimentally for some materials consisting of two interpenetrating incommensurate sub-lattices, such as Na x CoO 2 [3], Ca 3 Co 4 O 9 [4,5], and Bi 2−x Pb x Sr 2 Co 2 O y [5,6].…”

Section: Introductionmentioning

confidence: 99%

Lattice vibrations in the Frenkel-Kontorova Model. II. Thermal conductivity

2015

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We applied the formulae for the phonon spectral-density function that we presented in the previous paper of this series to analyze the thermal conductivity of the lattice in the framework of the Frenkel-Kontorova (FK) model. We found that two extra mechanisms of phonon scattering (different from the point impurities, three-phonon processes, and boundary scattering typical of all crystals), viz., resonance, and anharmonic scattering, that mainly influences the thermal conductivity of the lattice. The frequencies of resonance scattering are discrete, and their number increases from a finite number to infinity with their transition from the commensurate-to the incommensurate-state.Changing the amplitude and period of the FK model changes the frequencies and the frequency number of resonance scattering, and the intensity of anharmonic scattering.We analyze these changes in detail. Our theory can explain all existing numerical results on this problem, and also suggest strategies to reduce the thermal conductivity of the lattice of layered materials.

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“…One reason for this is that these materials have very low lattice thermal conductivity [3]. To understand their lattice thermal conductivity, we need to know the lattice vibrational properties of two inter-penetrating sublattices.…”

Section: Introductionmentioning

confidence: 99%

“…Recent investigations revealed that materials consisting of two interpenetrating incommensurate sub-lattices, such as Na x CoO 2 [1], Ca 3 Co 4 O 9 [2,3], and Bi 2−x Pb x Sr 2 Co 2 O y [2,4], have very good thermoelectric properties. One reason for this is that these materials have very low lattice thermal conductivity [3].…”

Section: Introductionmentioning

confidence: 99%

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Lattice vibrations in the Frenkel-Kontorova model. I. Phonon dispersion, number density, and energy

2015

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We studied the lattice vibrations of two inter-penetrating atomic sublattices via the Frenkel-Kontorova (FK) model of a linear chain of harmonically interacting atoms subjected to an on-site potential, using the technique of thermodynamic Green's functions based on quantum field-theoretical methods. General expressions were deduced for the phonon frequency-wave-vector dispersion relations, number density, and energy of the FK model system. As the application of the theory, we investigated in detail cases of linear chains with various periods of the on-site potential of the FK model. Some unusual but interesting features for different amplitudes of the on-site potential of the FK model are discussed. In the commensurate structure, the phonon spectrum always starts at a finite frequency, and the gaps of the spectrum are true ones with a zero density of modes. In the incommensurate structure, the phonon spectrum starts from zero frequency but at a nonzero wave vector; there are some modes inside these gap regions, but their density is very low. In our approximation, the energy of a higher-order commensurate state of the onedimensional system at finite temperature may become indefinitely close to the energy of an incommensurate state. This finding implies that the higher-order incommensuratecommensurate transitions are continuous ones, and that the phase transition may exhibit a "devil's staircase" behavior at a finite temperature.

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Thermal conductivity of the thermoelectric layered cobalt oxides measured by the Harman method

Cited by 87 publications

References 21 publications

Bruggeman's Exponents for Effective Thermal Conductivity of Lithium-Ion Battery Electrodes

Bruggeman's Exponents for Effective Thermal Conductivity of Lithium-Ion Battery Electrodes

Lattice vibrations in the Frenkel-Kontorova Model. II. Thermal conductivity

Lattice vibrations in the Frenkel-Kontorova model. I. Phonon dispersion, number density, and energy

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