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Title: Degradation Mechanisms of High Capacity 18650 Cells Containing Si-Graphite Anode and Nickel-Rich NMC Cathode

Abstract

Application of advanced anode and cathode materials in commercial lithium-ion batteries is attracting attention due to their high capacity. Silicon (Si)/graphite anodes and nickel (Ni)-rich lithium nickel manganese cobalt oxide with layered structures have been paired in commercial 18650 high energy density cells (~270 Wh/kg). It is crucial to investigate the cell performance and the aging behavior of this commercial cell. In this study, we present commercial cell degradation mechanisms by comparing fresh and aged electrodes, including changes of crystal structure, morphology, elemental composition, and electrochemical properties. The quantitative analysis was done based on dV/dQ incremental capacity analysis of 18650 cells. To determine the amount of cyclable lithium ions (Li +) and active material loss, the lithiation and delithiation capacity were compared for fresh and aged electrodes in half coin cells. Results showed that even with 5% (by mass) of Si added in the anode, cracks occurred across the anode leading to contact loss and thickening of the solid electrolyte interphase (SEI) layer. Additionally, the average fluorine (F) ratio of the aged anodes was higher compared to that of the fresh anodes. More severely, the F content on the Si aggregations on aged anodes increased to as high as 5more » times that of the fresh anode, indicating SEI growth, especially on Si particles. Solid 7Li nuclear magnetic resonance results showed no detectable Li metal deposition on the aged anode. On the cathode side, cracks on the primary particle interfaces contributed to cathode material loss, contact loss, and impedance rise. Furthermore, Li + loss into the thickened SEI layer, particle cracking, and impedance rise are the main reasons behind cell degradation.« less

Authors:
 [1];  [1];  [1];  [2];  [1];  [2];  [1];  [3];  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Tsinghua Univ., Beijing (China)
  3. Colorado School of Mines, Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE
OSTI Identifier:
1491439
Alternate Identifier(s):
OSTI ID: 1635855
Report Number(s):
NREL/JA-5400-72418
Journal ID: ISSN 0013-4686
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Electrochimica Acta
Additional Journal Information:
Journal Volume: 297; Journal Issue: C; Journal ID: ISSN 0013-4686
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; lithium ion batteries; degradation mechanisms; high capacity; Si-graphite anode; nickel-rich NMC cathode

Citation Formats

Li, Xuemin, Colclasure, Andrew M., Finegan, Donal P., Ren, Dongsheng, Shi, Ying, Feng, Xuning, Cao, Lei, Yang, Yuan, and Smith, Kandler. Degradation Mechanisms of High Capacity 18650 Cells Containing Si-Graphite Anode and Nickel-Rich NMC Cathode. United States: N. p., 2018. Web. doi:10.1016/j.electacta.2018.11.194.
Li, Xuemin, Colclasure, Andrew M., Finegan, Donal P., Ren, Dongsheng, Shi, Ying, Feng, Xuning, Cao, Lei, Yang, Yuan, & Smith, Kandler. Degradation Mechanisms of High Capacity 18650 Cells Containing Si-Graphite Anode and Nickel-Rich NMC Cathode. United States. https://doi.org/10.1016/j.electacta.2018.11.194
Li, Xuemin, Colclasure, Andrew M., Finegan, Donal P., Ren, Dongsheng, Shi, Ying, Feng, Xuning, Cao, Lei, Yang, Yuan, and Smith, Kandler. Tue . "Degradation Mechanisms of High Capacity 18650 Cells Containing Si-Graphite Anode and Nickel-Rich NMC Cathode". United States. https://doi.org/10.1016/j.electacta.2018.11.194. https://www.osti.gov/servlets/purl/1491439.
@article{osti_1491439,
title = {Degradation Mechanisms of High Capacity 18650 Cells Containing Si-Graphite Anode and Nickel-Rich NMC Cathode},
author = {Li, Xuemin and Colclasure, Andrew M. and Finegan, Donal P. and Ren, Dongsheng and Shi, Ying and Feng, Xuning and Cao, Lei and Yang, Yuan and Smith, Kandler},
abstractNote = {Application of advanced anode and cathode materials in commercial lithium-ion batteries is attracting attention due to their high capacity. Silicon (Si)/graphite anodes and nickel (Ni)-rich lithium nickel manganese cobalt oxide with layered structures have been paired in commercial 18650 high energy density cells (~270 Wh/kg). It is crucial to investigate the cell performance and the aging behavior of this commercial cell. In this study, we present commercial cell degradation mechanisms by comparing fresh and aged electrodes, including changes of crystal structure, morphology, elemental composition, and electrochemical properties. The quantitative analysis was done based on dV/dQ incremental capacity analysis of 18650 cells. To determine the amount of cyclable lithium ions (Li+) and active material loss, the lithiation and delithiation capacity were compared for fresh and aged electrodes in half coin cells. Results showed that even with 5% (by mass) of Si added in the anode, cracks occurred across the anode leading to contact loss and thickening of the solid electrolyte interphase (SEI) layer. Additionally, the average fluorine (F) ratio of the aged anodes was higher compared to that of the fresh anodes. More severely, the F content on the Si aggregations on aged anodes increased to as high as 5 times that of the fresh anode, indicating SEI growth, especially on Si particles. Solid 7Li nuclear magnetic resonance results showed no detectable Li metal deposition on the aged anode. On the cathode side, cracks on the primary particle interfaces contributed to cathode material loss, contact loss, and impedance rise. Furthermore, Li+ loss into the thickened SEI layer, particle cracking, and impedance rise are the main reasons behind cell degradation.},
doi = {10.1016/j.electacta.2018.11.194},
url = {https://www.osti.gov/biblio/1491439}, journal = {Electrochimica Acta},
issn = {0013-4686},
number = C,
volume = 297,
place = {United States},
year = {2018},
month = {12}
}

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