scholarly journals Femtosecond Laser Processing of Thick Film Cathodes and Its Impact on Lithium-Ion Diffusion Kinetics

2019 ◽  
Vol 9 (17) ◽  
pp. 3588 ◽  
Author(s):  
Wilhelm Pfleging ◽  
Petronela Gotcu
Keyword(s):  
Diffusion Coefficient ◽  
Thick Film ◽  
Active Material ◽  
Lithium Ion ◽  
Chemical Diffusion ◽  
Chemical Diffusion Coefficient ◽  
Ion Diffusion ◽  
Femtosecond Laser Processing ◽  
Specific Discharge ◽  
Li Ion

Quantitative experiments of lithiation/delithiation rates were considered for a better understanding of electrochemical intercalation/deintercalation processes in laser structured thick film cathodes. Besides galvanostatic cycling for evaluation of specific discharge capacities, a suitable quantitative approach for determining the rate of Li-ion insertion in the active material and the rate of Li-ion transport in the electrolyte is expressed by chemical diffusion coefficient values. For this purpose, the galvanostatic intermittent titration technique has been involved. It could be shown that laser structured electrodes provide an enhanced chemical diffusion coefficient and an improved capacity retention at high charging and discharging rates.

Synthesis and Electrochemical Properties of Spherical LiFePO4/C Composite via Spray Drying

2015 ◽  
Vol 1120-1121 ◽  
pp. 554-558 ◽  
Author(s):  
Juan Mei Wang ◽  
Bing Ren ◽  
Ying Lin Yan ◽  
Qing Zhang ◽  
Yan Wang
Keyword(s):  
Diffusion Coefficient ◽  
Electrochemical Properties ◽  
Spray Drying ◽  
Electrochemical Impedance ◽  
Retention Rate ◽  
Lithium Ion ◽  
Constant Current ◽  
Ion Diffusion ◽  
Electrochemical Tests ◽  
Li Ion

In this work, spherical LiFePO4/C composite had been synthesized by co-precipitation and spray drying method. The structure, morphology and electrochemical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscope (TEM), constant current charge-discharge tests and electrochemical impedance spectroscopy (EIS) tests. The spherical LiFePO4/C particles consisted of a number of smaller grains. The results showed that the morphology of LiFePO4/C particles seriously affected the Li-ion diffusion coefficient and electrochemical properties of lithium ion batteries. Electrochemical tests revealed the spherical LiFePO4/C composite had excellent Li-ion diffusion coefficient which was calculated to be 1.065×10-11 cm2/s and discharge capacity of 149 (0.1 C), 139 (0.2 C), 133 (0.5 C), 129 (1 C) and 124 mAhg-1(2 C). After 50 cycles, the capacity retention rate was still 93.5%.

Chemical diffusion coefficient of lithium ion in Li3V2(PO4)3 cathode material

2009 ◽  
Vol 63 (27) ◽  
pp. 2396-2398 ◽  
Author(s):  
Anping Tang ◽  
Xianyou Wang ◽  
Guorong Xu ◽  
Ronghua Peng ◽  
Huidong Nie
Keyword(s):  
Diffusion Coefficient ◽  
Cathode Material ◽  
Lithium Ion ◽  
Chemical Diffusion ◽  
Chemical Diffusion Coefficient

scholarly journals Effect of Ni2+ on Lithium-Ion Diffusion in Layered LiNi1−x−yMnxCoyO2 Materials

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 465
Author(s):  
Yuanyuan Zhu ◽  
Yang Huang ◽  
Rong Du ◽  
Ming Tang ◽  
Baotian Wang ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Lithium Ion ◽  
Ion Diffusion ◽  
Local Coordination ◽  
Excellent Electrochemical Performance ◽  
Layered Cathode Materials ◽  
Li Ion ◽  
Dynamics Simulations ◽  
And Diffusion ◽  
Lithium Ion Diffusion

LiNi1−x−yMnxCoyO2 materials are a typical class of layered cathode materials with excellent electrochemical performance in lithium-ion batteries. Molecular dynamics simulations are performed for LiNi1−x−yMnxCoyO2 materials with different transition metal ratios. The Li/Ni exchange ratio, ratio of anti-site Ni2+ to total Ni2+, and diffusion coefficient of Li ions in these materials are calculated. The results show that the Li-ion diffusion coefficient strongly depends on the ratio of anti-site Ni2+ to total Ni2+ because their variation tendencies are similar. In addition, the local coordination structure of the Li/Ni anti-site is analyzed.

scholarly journals Boundary layer analysis for a 2-D Keller-Segel model

2020 ◽  
Vol 18 (1) ◽  
pp. 1895-1914
Author(s):  
Linlin Meng ◽  
Wen-Qing Xu ◽  
Shu Wang
Keyword(s):  
Boundary Layer ◽  
Diffusion Coefficient ◽  
Approximate Solution ◽  
Chemical Diffusion ◽  
Singular Perturbation Theory ◽  
Energy Estimates ◽  
Chemical Diffusion Coefficient ◽  
Boundary Layer Problem ◽  
Classical Energy ◽  
Layer Analysis

Abstract We study the boundary layer problem of a Keller-Segel model in a domain of two space dimensions with vanishing chemical diffusion coefficient. By using the method of matched asymptotic expansions of singular perturbation theory, we construct an accurate approximate solution which incorporates the effects of boundary layers and then use the classical energy estimates to prove the structural stability of the approximate solution as the chemical diffusion coefficient tends to zero.

Lithium Ion Diffusion Through Glassy Carbon Plate

1997 ◽  
Vol 496 ◽  
Author(s):  
M. Inaba ◽  
S. Nohmi ◽  
A. Funabiki ◽  
T. Abe ◽  
Z. Ogumi
Keyword(s):  
Diffusion Coefficient ◽  
Glassy Carbon ◽  
Lithium Ion ◽  
Ion Diffusion ◽  
Irreversible Capacity ◽  
Oxidation Current ◽  
Current Curve ◽  
Carbon Plate ◽  
Lithium Ion Diffusion

ABSTRACTThe electrochemical permeation method was applied to the determination of the diffusion coefficient of Li+ion (DLi+) in a glassy carbon (GC) plate. The cell was composed of two compartments, which were separated by the GC plate. Li+ions were inserted electrochemically from one face, and extracted from the other. The flux of the permeated Li+ions was monitored as an oxidation current at the latter face. The diffusion coefficient was determined by fitting the transient current curve with a theoretical one derived from Fick's law. When the potential was stepped between two potentials in the range of 0 to 0.5 V, transient curves were well fitted with the theoretical one, which gaveDLi+ values on the order of 10−8cm2s−1. In contrast, when the potential was stepped between two potentials across 0.5 V, significant deviation was observed. The deviation indicated the presence of trap sites as well as diffusion sites for Li+ions, the former of which is the origin of the irreversible capacity of GC.

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