Complementary analyses of aging in a commercial LiFePO4/graphite 26650 cell

Roberto Scipioni, Peter S. Jørgensen, Daniel I. Stroe, Reza Younesi, Søren B. Simonsen, Poul Norby, Johan Hjelm, Søren H. Jensen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

In this work we investigate the electrode degradation mechanisms in a commercial 2.5 Ah LiFePO4/graphite 26650 cylindrical cell. Aged and fresh electrode samples were prepared by cycling two cells respectively five and 22 k times. Subsequently the cells were disassembled in a glovebox and the electrode samples were prepared for electrochemical testing in a 3-electrode setup, and for characterization with XRD, XPS and low-kV FIB/SEM tomography. A 1 μm thick CEI (cathode electrolyte interface) layer was observed at the electrode/electrolyte interface of the aged LiFePO4 electrode. Relative to the fresh LiFePO4 electrode, the aged electrode exhibited a larger series resistance which indicates the observed degradation layer increases the ionic resistance. In addition, micron-sized agglomerates, probably a mixture of carbonaceous material and decomposition products from the electrolyte, were observed at the electrode/electrolyte interface of the aged graphite electrode. These layers may contribute significantly to the loss of lithium inventory (LLI) in the cell, and to the loss of active material (LAM) in the graphite electrode. Low-voltage FIB/SEM tomography was used to detect local charging effects of graphite particles in the carbon electrode, an effect of poor dissipation of the electric charge to the ground after the sample interaction with the electron beam. The charging effects were primarily observed in the aged electrode and most of the locally charged particles were found to be close to the electrode/electrolyte interface, indicating a poorly percolating graphite network near this interface.

Original languageEnglish
JournalElectrochimica Acta
Volume284
Pages (from-to)454-468
ISSN0013-4686
DOIs
Publication statusPublished - 10 Sep 2018

Keywords

  • Cathode electrolyte interface
  • Degradation mechanisms
  • Electrochemical impedance spectroscopy
  • Focused ion beam
  • Li-ion battery

Cite this

@article{487555ed6e7f48bdb82e1a71b7aac838,
title = "Complementary analyses of aging in a commercial LiFePO4/graphite 26650 cell",
abstract = "In this work we investigate the electrode degradation mechanisms in a commercial 2.5 Ah LiFePO4/graphite 26650 cylindrical cell. Aged and fresh electrode samples were prepared by cycling two cells respectively five and 22 k times. Subsequently the cells were disassembled in a glovebox and the electrode samples were prepared for electrochemical testing in a 3-electrode setup, and for characterization with XRD, XPS and low-kV FIB/SEM tomography. A 1 μm thick CEI (cathode electrolyte interface) layer was observed at the electrode/electrolyte interface of the aged LiFePO4 electrode. Relative to the fresh LiFePO4 electrode, the aged electrode exhibited a larger series resistance which indicates the observed degradation layer increases the ionic resistance. In addition, micron-sized agglomerates, probably a mixture of carbonaceous material and decomposition products from the electrolyte, were observed at the electrode/electrolyte interface of the aged graphite electrode. These layers may contribute significantly to the loss of lithium inventory (LLI) in the cell, and to the loss of active material (LAM) in the graphite electrode. Low-voltage FIB/SEM tomography was used to detect local charging effects of graphite particles in the carbon electrode, an effect of poor dissipation of the electric charge to the ground after the sample interaction with the electron beam. The charging effects were primarily observed in the aged electrode and most of the locally charged particles were found to be close to the electrode/electrolyte interface, indicating a poorly percolating graphite network near this interface.",
keywords = "Cathode electrolyte interface, Degradation mechanisms, Electrochemical impedance spectroscopy, Focused ion beam, Li-ion battery",
author = "Roberto Scipioni and J{\o}rgensen, {Peter S.} and Stroe, {Daniel I.} and Reza Younesi and Simonsen, {S{\o}ren B.} and Poul Norby and Johan Hjelm and Jensen, {S{\o}ren H.}",
year = "2018",
month = "9",
day = "10",
doi = "10.1016/j.electacta.2018.07.124",
language = "English",
volume = "284",
pages = "454--468",
journal = "Electrochimica Acta",
issn = "0013-4686",
publisher = "Pergamon Press",

}

Complementary analyses of aging in a commercial LiFePO4/graphite 26650 cell. / Scipioni, Roberto; Jørgensen, Peter S.; Stroe, Daniel I.; Younesi, Reza; Simonsen, Søren B.; Norby, Poul; Hjelm, Johan; Jensen, Søren H.

In: Electrochimica Acta, Vol. 284, 10.09.2018, p. 454-468.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Complementary analyses of aging in a commercial LiFePO4/graphite 26650 cell

AU - Scipioni, Roberto

AU - Jørgensen, Peter S.

AU - Stroe, Daniel I.

AU - Younesi, Reza

AU - Simonsen, Søren B.

AU - Norby, Poul

AU - Hjelm, Johan

AU - Jensen, Søren H.

PY - 2018/9/10

Y1 - 2018/9/10

N2 - In this work we investigate the electrode degradation mechanisms in a commercial 2.5 Ah LiFePO4/graphite 26650 cylindrical cell. Aged and fresh electrode samples were prepared by cycling two cells respectively five and 22 k times. Subsequently the cells were disassembled in a glovebox and the electrode samples were prepared for electrochemical testing in a 3-electrode setup, and for characterization with XRD, XPS and low-kV FIB/SEM tomography. A 1 μm thick CEI (cathode electrolyte interface) layer was observed at the electrode/electrolyte interface of the aged LiFePO4 electrode. Relative to the fresh LiFePO4 electrode, the aged electrode exhibited a larger series resistance which indicates the observed degradation layer increases the ionic resistance. In addition, micron-sized agglomerates, probably a mixture of carbonaceous material and decomposition products from the electrolyte, were observed at the electrode/electrolyte interface of the aged graphite electrode. These layers may contribute significantly to the loss of lithium inventory (LLI) in the cell, and to the loss of active material (LAM) in the graphite electrode. Low-voltage FIB/SEM tomography was used to detect local charging effects of graphite particles in the carbon electrode, an effect of poor dissipation of the electric charge to the ground after the sample interaction with the electron beam. The charging effects were primarily observed in the aged electrode and most of the locally charged particles were found to be close to the electrode/electrolyte interface, indicating a poorly percolating graphite network near this interface.

AB - In this work we investigate the electrode degradation mechanisms in a commercial 2.5 Ah LiFePO4/graphite 26650 cylindrical cell. Aged and fresh electrode samples were prepared by cycling two cells respectively five and 22 k times. Subsequently the cells were disassembled in a glovebox and the electrode samples were prepared for electrochemical testing in a 3-electrode setup, and for characterization with XRD, XPS and low-kV FIB/SEM tomography. A 1 μm thick CEI (cathode electrolyte interface) layer was observed at the electrode/electrolyte interface of the aged LiFePO4 electrode. Relative to the fresh LiFePO4 electrode, the aged electrode exhibited a larger series resistance which indicates the observed degradation layer increases the ionic resistance. In addition, micron-sized agglomerates, probably a mixture of carbonaceous material and decomposition products from the electrolyte, were observed at the electrode/electrolyte interface of the aged graphite electrode. These layers may contribute significantly to the loss of lithium inventory (LLI) in the cell, and to the loss of active material (LAM) in the graphite electrode. Low-voltage FIB/SEM tomography was used to detect local charging effects of graphite particles in the carbon electrode, an effect of poor dissipation of the electric charge to the ground after the sample interaction with the electron beam. The charging effects were primarily observed in the aged electrode and most of the locally charged particles were found to be close to the electrode/electrolyte interface, indicating a poorly percolating graphite network near this interface.

KW - Cathode electrolyte interface

KW - Degradation mechanisms

KW - Electrochemical impedance spectroscopy

KW - Focused ion beam

KW - Li-ion battery

U2 - 10.1016/j.electacta.2018.07.124

DO - 10.1016/j.electacta.2018.07.124

M3 - Journal article

VL - 284

SP - 454

EP - 468

JO - Electrochimica Acta

JF - Electrochimica Acta

SN - 0013-4686

ER -