scholarly journals Significant Reduction in Thermal Conductivity of Lithium Cobalt Oxide Cathode Upon Charging: Propagating and Non-propagating Thermal Energy Transport

2018 ◽  
Author(s):  
Shiqian Hu ◽  
◽  
Zhongwei Zhang ◽  
Zhongting Wang ◽  
Kaiyang Zeng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Cobalt Oxide ◽  
Thermal Energy ◽  
Energy Transport ◽  
Lithium Cobalt Oxide ◽  
Oxide Cathode ◽  
Thermal Energy Transport ◽  
Lithium Cobalt

scholarly journals Equilibrium Molecular Dynamics Study of Lattice Thermal Conductivity/Conductance of Au-SAM-Au Junctions

2009 ◽  
Vol 132 (3) ◽  
Author(s):  
Tengfei Luo ◽  
John R. Lloyd
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Energy ◽  
Energy Transport ◽  
Thermal Conductance ◽  
Finite Size ◽  
Thickness Effect ◽  
Finite Size Effect ◽  
Substrate Thickness ◽  
Thermal Energy Transport

In this paper, equilibrium molecular dynamics simulations were performed on Au-SAM (self-assembly monolayer)-Au junctions. The SAM consisted of alkanedithiol (–S–(CH2)n–S–) molecules. The out-of-plane (z-direction) thermal conductance and in-plane (x- and y-direction) thermal conductivities were calculated. The simulation finite size effect, gold substrate thickness effect, temperature effect, normal pressure effect, molecule chain length effect, and molecule coverage effect on thermal conductivity/conductance were studied. Vibration power spectra of gold atoms in the substrate and sulfur atoms in the SAM were calculated, and vibration coupling of these two parts was analyzed. The calculated thermal conductance values of Au-SAM-Au junctions are in the range of experimental data on metal-nonmetal junctions. The temperature dependence of thermal conductance has a similar trend to experimental observations. It is concluded that the Au-SAM interface resistance dominates thermal energy transport across the junction, while the substrate is the dominant media in which in-plane thermal energy transport happens.

Physical Mechanisms of Thermal Transport in Nanofluids

2011 ◽  
Author(s):  
John Shelton ◽  
Frank Pyrtle
Keyword(s):  
Thermal Conductivity ◽  
Thermal Energy ◽  
Energy Exchange ◽  
System Analysis ◽  
Energy Transport ◽  
Physical Mechanism ◽  
Conductivity Enhancement ◽  
Physical Mechanisms ◽  
Dynamics Simulations ◽  
Thermal Energy Transport

Using molecular dynamics simulations, an analysis of the thermal conductivity enhancement of a copper/argon nanofluid is performed. First, verification of an increase of as much as ∼30% in the thermal conductivity of the theoretical nanofluid over the corresponding base fluid, due to increasing nanoparticle concentration, is presented. Thermal energy transport is then decomposed into potential, kinetic, and virial components, based on the Green-Kubo autocorrelation function used to calculate thermal conductivity from the microscopic properties of the system. Analysis of these components showed that as the concentration of the nanoparticle increases, the energy transported through the system, due to collisions within the fluid, decreases by as much as 80%. Additionally, the nanofluid system increasingly displays characteristics of an amorphous-like material with increasing concentration. The decrease in energy exchange, due to collisions, suggests another physical mechanism is present for thermal energy transport. Therefore, it is proposed that thermal diffusion is the physical mechanism that more significantly affects thermal energy transport within a nanofluid than had been previously suggested.

Thin Film Phonon Heat Conduction by the Dispersion Lattice Boltzmann Method

2007 ◽  
Author(s):  
Rodrigo A. Escobar ◽  
Cristina H. Amon ◽  
Amador M. Guzma´n
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Lattice Boltzmann Method ◽  
Thermal Energy ◽  
Lattice Boltzmann ◽  
Energy Transport ◽  
Time Dependent ◽  
Boltzmann Method ◽  
Thermal Energy Transport

Numerical simulations of time-dependent thermal energy transport in semiconductor thin films are performed using the Lattice Boltzmann Method applied to phonon transport. The discrete Lattice Boltzmann Method is derived from the continuous Boltzmann transport equation assuming nonlinear, frequency-dependent phonon dispersion for acoustic and optical phonons. Results indicate that the heat conduction in silicon thin films displays a transition from diffusive to ballistic energy transport as the characteristic length of the system becomes comparable to the phonon mean free path, and that the thermal energy transport process is characterized by the propagation of multiple, superimposed phonon waves. The methodology is used to characterize the time-dependent temperature profiles inside films of decreasing thickness. Thickness-dependent thermal conductivity values are computed based on steady-state temperature distributions obtained from the numerical models. It is found that reducing feature size into the subcontinuum regime decreases the thermal conductivity when compared to bulk values, at a higher rate than what was displayed by the Debye-based gray Lattice Boltzmann Method.

Maintaining structural integrity of 4.5 V lithium cobalt oxide cathode with fumaronitrile as a novel electrolyte additive

2017 ◽  
Vol 338 ◽  
pp. 108-116 ◽  
Author(s):  
Xianshu Wang ◽  
Xiongwen Zheng ◽  
Youhao Liao ◽  
Qiming Huang ◽  
Lidan Xing ◽  
...  
Keyword(s):  
Cobalt Oxide ◽  
Structural Integrity ◽  
Lithium Cobalt Oxide ◽  
Electrolyte Additive ◽  
Oxide Cathode ◽  
Lithium Cobalt
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