Disassembly Investigation of Batteries and Capacitors,
Investigation for Deterioration and Defect,
and Structural Analysis

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Investigation of Causes of Deterioration & Failure of Batteries and Capacitors

JFE Techno-Research (JFE-TEC) investigates the causes of trouble and failure such as poor performance, swelling, fire, etc. in batteries, capacitors, and other energy devices with a wide range of sizes, from large-scale automotive cells to mobile phone batteries.

JFE-TEC can also investigate the cause and mechanism of battery deterioration by examination of battery parts after long-term deterioration tests.

In addition to investigation of battery parts by disassembling cells, we also assess the state of deterioration and study its cause by nondestructive investigation of the internal structure by X-ray fluoroscopy and X-ray CT.

It is also possible to investigate the location of internal short circuits and contamination by foreign matters by analysis of the condition of heat generation by infrared camera.

Causes of Deterioration & Failure of Lithium-Ion Batteries

  • Deterioration of lithium-ion battery

    Phenomena in which the internal resistance of a battery increases, charging capacity decreases, etc.

    [Main causes of deterioration]

    • Formation of film on electrode surface (results in: increased internal resistance,decreased electrode adhesion)
    • Delamination of electrode (results in: impossible charging at delaminated parts)
    • Decreased migration of Li ions (results in: deposition of metallic Li, etc. on electrode surface)
  • Failure of lithium-ion batteries

    Phenomena including deterioration of performance, swelling of the cell, leakage of the electrolyte, smoke, fire, etc. immediately after start of use

    [Main causes of deterioration]

    • Leakage of moisture into electrolyte or residual moisture due to inadequate drying of electrode
      Li + H2O → LiOH + 1/2H2
    • Formation of HF (hydrofluoric acid) by reaction of residual moisture and electrolyte
      LiPF6 → PF5 + LiF PF5 + H2O → PF3O + 2HF
    • Heat generation/fire due to internal short circuit caused by contamination by foreign matters or improper cell assembly

Examples of Investigation of Causes of Deterioration/Failure of Li-Ion Battery

Example of Investigation of Deterioration of Mobile Phone Li-Ion Battery after Long-term Use

Example of Investigation of Cause of Swelling of Mobile Phone Lithium Ion Battery Immediately after Start of Use

Total amount of gas in the swollen cell was about 6 times that in a good new cell, and most of the gas was hydrogen.

Contamination of cell by water and/or overcharging was presumed to be the cause of swollenness of cell.

Analysis methods for component materials of batteries and capacitors

Material Purpose Method
Electrode Electrode/active
material
(incl. conductive aid)
Identification of crystal structure and components of electrode X-ray diffraction
Elemental composition analysis ICP
Cross-section structure analysis FIB, cross-section Ar milling
Surface state analysis XPS
Negative
electrode
/active
material
(incl. conductive aid)
Graphite content of graphite negative electrode
Crystalline orientation, crystal size
X-ray diffraction
Cross-section structure analysis FIB-SEM, CP-SEM
Surface state analysis XPS
Binder Analysis of components of binder and thickener FT-IR
Thermal
decomposition- GC-MS
Tab lead Ultrasonic welding state investigation Cross sectional SEM
Separator Components Microscopic FT-IR
Layer composition SEM, microscopic Raman
Electrolyte
solution
Solvent Moisture content analysis of main
component, impurity and modified product
GC, GC-MS Karl Fischer method
Electrolyte Component analysis LC-MS, ICP
Additive Component analysis FT-IR, GC-MS
Cladding    

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