Mechanical Degradation Behavior of Single Crystal LiNixMnyCozO2 Cathode in Li-ion Battery by Indentation Analysis

2022 ◽  
Author(s):  
Ying Chen ◽  
Weiling Luan ◽  
Xuanchen Zhu ◽  
Haofeng Chen
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Sample Preparation ◽  
Electrochemical Performance ◽  
Single Crystal ◽  
Active Material ◽  
Composite Cathode ◽  
Mechanical Degradation ◽  
Cycling Process ◽  
Li Ion

Abstract LiNixMnyCozO2 (NMC) is among the most promising cathode materials for commercial Li-ion batteries due to its high electrochemical performance. However, NMC composite cathode is still plagued with limited cyclic performance, which is influenced by its structural stability during the cycling process. The cathode, which comprises of the active material, polymeric binder, and porous conductive matrix, often exhibits large structural variation during the electrochemical cycling process. This inevitably increases the challenge of measuring the mechanical properties of the material. Even though single crystal NMC possesses better stability as compared to the polycrystalline NMC, the electrochemical performance degradation of single crystal NMC cathode remains relatively unexplored. Different sample preparation methods are compared systematically in accordance to the previous report, and a new method of sample preparation is proposed. Nanoindentation instrument is used to measure the elastic modulus and hardness of the single crystal NMC particles. The measured elastic modulus and hardness of NMC particles, under different electrochemical environments, are dependent on a large number of nanoindentation experiments and statistical analysis of the result obtained from the carefully prepared samples. The sample preparation method is the key factor that can significantly influence the nanoindentation experiment results of the NMC particles. This work shows that the mechanical properties of the single crystal NMC particles degrade significantly with number of electrochemical cycles. The decreasing elastic modulus with the number of electrochemical cycles can be fitted using a two-parameter logarithm model.

The Effect of Solid Solution Impurities on Dislocation Nucleation in a (001) Mo – 1.5 at.% Ir Single Crystal

2010 ◽  
Vol 662 ◽  
pp. 85-93
Author(s):  
Sergey Dub ◽  
Igor Zasimchuk ◽  
Leonid Matvienko
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Shear Stress ◽  
Elastic Modulus ◽  
Single Crystal ◽  
Single Crystals ◽  
Free Volume ◽  
Dislocation Nucleation ◽  
Initial Portion ◽  
G 12

Mechanical properties of (001) Mo and (001) Mo – 1.5 at.% Ir single crystals have been studied by nanoindentation. It has been found that the iridium addition to molybdenum leads to an increase in both hardness and elastic modulus. An abrupt elasto-plastic transition (pop-in) at a depth of about 20 - 40 nm caused by dislocation nucleation in previously dislocation-free volume has been observed in the initial portion of the loading curve. It has shown that the Ir addition essentially affects the dislocation nucleation. Mean shear stress required for the dislocation nucleation increased from 10.8 GPa (G/12) for a Mo single crystal to 18.2 GPa (G/8) for the Mo – 1.5 at% Ir solid solution. Thus, the Ir solution in a Mo single crystal affects not only the resistance to the motion of dislocations (hardness) but the nucleation of them as well. The latter is likely to occur as a result of an increase in the structure perfection of the Mo – 1.5 at% Ir solid solution as compared to the pure Mo single crystal.

Dual active material composite cathode structures for Li-ion batteries

2008 ◽  
Vol 177 (2) ◽  
pp. 528-536 ◽  
Author(s):  
J.F. Whitacre ◽  
K. Zaghib ◽  
W.C. West ◽  
B.V. Ratnakumar
Keyword(s):  
Active Material ◽  
Composite Cathode ◽  
Li Ion Batteries ◽  
Li Ion ◽  
Material Composite

scholarly journals Mechanical Properties of 3C-SiC Films for MEMS Applications

2007 ◽  
Vol 1049 ◽  
Author(s):  
Jayadeep Deva Reddy ◽  
Alex A. Volinsky ◽  
Christopher L. Frewin ◽  
Chris Locke ◽  
Stephen E. Saddow
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Plastic Deformation ◽  
Elastic Modulus ◽  
Single Crystal ◽  
Elastic Contact ◽  
Si Substrates ◽  
Sic Films

AbstractThere is a technological need for hard thin films with high elastic modulus and fracture toughness. Silicon carbide (SiC) fulfills such requirements for a variety of applications at high temperatures and for high-wear MEMS. A detailed study of the mechanical properties of single crystal and polycrystalline 3C-SiC films grown on Si substrates was performed by means of nanoindentation using a Berkovich diamond tip. The thickness of both the single and polycrystalline SiC films was around 1-2 μm. Under indentation loads below 500 μN both films exhibit Hertzian elastic contact without plastic deformation. The polycrystalline SiC films have an elastic modulus of 457 GPa and hardness of 33.5 GPa, while the single crystalline SiC films elastic modulus and hardness were measured to be 433 GPa and 31.2 GPa, respectively. These results indicate that polycrystalline SiC thin films are more attractive for MEMS applications when compared with the single crystal 3C-SiC, which is promising since growing single crystal 3C-SiC films is more challenging.

A Novel Composite Li3V2(PO4)3∥Li2NaV2(PO4)3/C as Cathode Material for Li-Ion Batteries

2018 ◽  
Vol 71 (7) ◽  
pp. 497
Author(s):  
Lingfang Li ◽  
Changling Fan ◽  
Jiaxing Yang
Keyword(s):  
Electrochemical Performance ◽  
Metal Ion ◽  
Coulombic Efficiency ◽  
Sol Gel ◽  
Lithium Ion ◽  
Composite Cathode ◽  
X Ray Diffraction ◽  
Li Ion ◽  
Ion Intercalation ◽  
Charge Discharge

A novel composite cathode for lithium ion batteries, Li3V2(PO4)3‖Li2NaV2(PO4)3/C, was synthesized by a sol-gel method. Cetyltrimethylammonium bromide (CTAB) was used as a surfactant while polyvinylidene difluoride (PVDF) was the carbon source. X-ray diffraction (XRD) and Raman results showed that the components of this composite are monoclinic Li3V2(PO4)3, rhombohedral Li2NaV2(PO4)3 and an amorphous carbon-coating. Four potential plateaus occur at the charge/discharge curves and the longest plateau is observed at a potential of 3.8/3.7 V. Therefore, the alkali metal ion intercalation and deintercalation mostly occur at this potential, which is different to that observed for Li3V2(PO4)3. In addition to the stable working potential, this composite also possesses an outstanding electrochemical performance. The sample containing 8.32 % carbon content delivers a capacity of 119 mAh g−1 at 0.2 C rate and 87 mAh g−1 at 12 C. After 50 charge/discharge cycles at 1 C, a coulombic efficiency of 98.4 % is maintained. This enhancement of the electrochemical performance could be attributed to the synergistic effect between monoclinic Li3V2(PO4)3 and rhombohedral Li2NaV2(PO4)3.

Electrospun LiFexMn1-xPO4/C Composite Nanofibers for Lithium-Ion Batteries

2021 ◽  
Vol 58 (2) ◽  
pp. 211-219
Author(s):  
Ozan Toprakci
Keyword(s):  
Energy Density ◽  
Electrochemical Performance ◽  
Cathode Materials ◽  
Composite Nanofibers ◽  
Active Material ◽  
Lithium Ion ◽  
Li Ion Batteries ◽  
Step Method ◽  
Long Cycle Life ◽  
Li Ion

Since the commercialization of Li-ion batteries by Sony in 1990, the performance of cathode materials used in Li-ion batteries has improved significantly. However, Li-ion batteries cannot respond to the needs of the energy storage market in terms of energy density. In order to increase theoretical energy density of active materials, molar mass of the active material should be decreased, or electron number participating per reaction or reaction potential should be increased. In this study, it was aimed to produce cathode materials for Li-ion batteries in the form of composite nanofibers via electrospinning method. For this purpose, porous LiFexMn1-xPO4/C composite nanofibers (1 ] x ] 0) were synthesized with a scalable, two-step method (electrospinning and subsequent heat treatment). The morphological, structural and electrochemical properties of the LiFexMn1-xPO4/C composite nanofibers were determined by scanning electron microscope, X-ray diffraction and galvanostatic charge/discharge tests. Cathodes made of LiFexMn1-xPO4/C composite nanofibers showed various advantages such as long cycle life, improved electrochemical performance etc. due to the presence of carbon and LiFexMn1-xPO4 in the composite structure. With the addition of Mn to the structure of LiFePO4/C composite nanofibers, electrochemical performance was improved. LiFe0.8Mn0.2PO4/C composite nanofibers showed the best performance in terms of energy density among the samples. Further increment in Mn/Fe ratio resulted declining electrochemical capacity and energy density.

Mechanistic understanding of intergranular cracking in NCM cathode material: mesoscale simulation with three-dimensional microstructure

2018 ◽  
Vol 20 (42) ◽  
pp. 27115-27124 ◽  
Author(s):  
Kyoungmin Min ◽  
Eunseog Cho
Keyword(s):  
Mechanical Properties ◽  
Cathode Materials ◽  
Three Dimensional ◽  
Mechanical Degradation ◽  
Li Ion Batteries ◽  
Intergranular Cracking ◽  
Mesoscale Simulation ◽  
Secondary Particles ◽  
Oxide Cathode ◽  
Li Ion

Intergranular cracking in the agglomerated form of secondary particles has been regarded as a major cause for mechanical degradation in layered oxide cathode materials for Li-ion batteries, but its detailed mechanistic origin linked to the mechanical properties of these materials is still unknown.

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