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Title: The effect of charging rate on the graphite electrode of commercial lithium-ion cells: A post-mortem study

Increased charging rates negatively affect the lifetime of lithium-ion cells by increasing cell resistance and reducing capacity. This work is a post-mortem study of 18650 cells subjected to charge rates of 0.7-, 2-, 4-, and 6-C. For cells charged at 0.7-C to 4-C, this performance degradation is primarily related to surface film thickness with no observable change in surface film chemical composition. However, at charge rates of 6-C, the chemical composition of the surface film changes significantly, suggesting that this change is the reason for the sharper increase in cell resistance compared to the lower charge rates. In addition, we found that surface film formation was not uniform across the electrode. Surface film was thicker and chemically different along the central band of the electrode “jelly roll”. This result is most likely attributable to an increase in temperature that results from non-uniform electrode wetting during manufacture. As a result, this non-uniform change further resulted in active material delamination from the current collector owing to chemical changes to the binder for the cell charged at 6-C.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [4] ;  [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Warwick, England (United Kingdom)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Univ. of Warwick, England (United Kingdom)
  4. Jaguar Land Rover, England (United Kingdom)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Power Sources
Additional Journal Information:
Journal Volume: 335; Journal Issue: C; Journal ID: ISSN 0378-7753
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
WMG centre HVM Catapult; Engineering and Physical Sciences Research Council (EPSRC); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); Jaguar Land Rover
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 36 MATERIALS SCIENCE; Lithium-ion; aging; increased charge rate; materials characterization
OSTI Identifier:
1339417