Probing the roles of polymeric separators in lithium-ion battery capacity fade at elevated temperatures

Jianchao Chen, Yongda Yan, Tao Sun, Yue Qi, Xiaodong Li

    Research output: Contribution to journalArticle

    • 6 Citations

    Abstract

    The high temperature mechanical property of separators is very important for safety of lithium-ion batteries. However, the mechanical integrity of polymeric separators in lithium-ion batteries at elevated temperatures is still not well characterized. In this paper, the temperature dependent micro-scale morphology change of PP (polypropylene)-PE (polyethylene)-PP sandwiched separators (Celgard 2325) was studied by in-situ high temperature surface imaging using an atomic force microscope (AFM) coupled with power spectral density (PSD) analysis and digital image correlation (DIC) technique. Both PSD and DIC analysis results show that the PP phase significantly closes its pores by means of dilation of the nanofibrils surrounding the pores in the transverse direction and shrinkage in the machine direction, when cycled at 90°C, even below the separator's shutdown temperature (∼120°C) and its own melting temperature (165°C). This is presumably due to surface melting effect in nanostructures and should be size dependent-the surface melting temperature may decrease with the diameter of nanofibrils. Therefore, some pore closing might happen even at operating temperatures, it will lead to capacity fade that is undesired for battery performance.

    Original languageEnglish (US)
    JournalJournal of the Electrochemical Society
    Volume161
    Issue number9
    DOIs
    StatePublished - 2014

    Profile

    temperature
    Acetanilides
    Temperature
    separators
    alpha-Crystallin B Chain
    Separators
    electric batteries
    polypropylene
    lithium
    melting
    porosity
    ions
    Edema Disease of Swine
    Directed Tissue Donation
    Polypropylenes
    Lithium-ion batteries
    Idoxuridine
    Motor Activity
    Power spectral density
    Melting point

    ASJC Scopus subject areas

    • Materials Chemistry
    • Surfaces, Coatings and Films
    • Renewable Energy, Sustainability and the Environment
    • Condensed Matter Physics
    • Electrochemistry
    • Electronic, Optical and Magnetic Materials

    Cite this

    Probing the roles of polymeric separators in lithium-ion battery capacity fade at elevated temperatures. / Chen, Jianchao; Yan, Yongda; Sun, Tao; Qi, Yue; Li, Xiaodong.

    In: Journal of the Electrochemical Society, Vol. 161, No. 9, 2014.

    Research output: Contribution to journalArticle

    Chen, Jianchao; Yan, Yongda; Sun, Tao; Qi, Yue; Li, Xiaodong / Probing the roles of polymeric separators in lithium-ion battery capacity fade at elevated temperatures.

    In: Journal of the Electrochemical Society, Vol. 161, No. 9, 2014.

    Research output: Contribution to journalArticle

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    abstract = "The high temperature mechanical property of separators is very important for safety of lithium-ion batteries. However, the mechanical integrity of polymeric separators in lithium-ion batteries at elevated temperatures is still not well characterized. In this paper, the temperature dependent micro-scale morphology change of PP (polypropylene)-PE (polyethylene)-PP sandwiched separators (Celgard 2325) was studied by in-situ high temperature surface imaging using an atomic force microscope (AFM) coupled with power spectral density (PSD) analysis and digital image correlation (DIC) technique. Both PSD and DIC analysis results show that the PP phase significantly closes its pores by means of dilation of the nanofibrils surrounding the pores in the transverse direction and shrinkage in the machine direction, when cycled at 90°C, even below the separator's shutdown temperature (∼120°C) and its own melting temperature (165°C). This is presumably due to surface melting effect in nanostructures and should be size dependent-the surface melting temperature may decrease with the diameter of nanofibrils. Therefore, some pore closing might happen even at operating temperatures, it will lead to capacity fade that is undesired for battery performance.",
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    AU - Li,Xiaodong

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    N2 - The high temperature mechanical property of separators is very important for safety of lithium-ion batteries. However, the mechanical integrity of polymeric separators in lithium-ion batteries at elevated temperatures is still not well characterized. In this paper, the temperature dependent micro-scale morphology change of PP (polypropylene)-PE (polyethylene)-PP sandwiched separators (Celgard 2325) was studied by in-situ high temperature surface imaging using an atomic force microscope (AFM) coupled with power spectral density (PSD) analysis and digital image correlation (DIC) technique. Both PSD and DIC analysis results show that the PP phase significantly closes its pores by means of dilation of the nanofibrils surrounding the pores in the transverse direction and shrinkage in the machine direction, when cycled at 90°C, even below the separator's shutdown temperature (∼120°C) and its own melting temperature (165°C). This is presumably due to surface melting effect in nanostructures and should be size dependent-the surface melting temperature may decrease with the diameter of nanofibrils. Therefore, some pore closing might happen even at operating temperatures, it will lead to capacity fade that is undesired for battery performance.

    AB - The high temperature mechanical property of separators is very important for safety of lithium-ion batteries. However, the mechanical integrity of polymeric separators in lithium-ion batteries at elevated temperatures is still not well characterized. In this paper, the temperature dependent micro-scale morphology change of PP (polypropylene)-PE (polyethylene)-PP sandwiched separators (Celgard 2325) was studied by in-situ high temperature surface imaging using an atomic force microscope (AFM) coupled with power spectral density (PSD) analysis and digital image correlation (DIC) technique. Both PSD and DIC analysis results show that the PP phase significantly closes its pores by means of dilation of the nanofibrils surrounding the pores in the transverse direction and shrinkage in the machine direction, when cycled at 90°C, even below the separator's shutdown temperature (∼120°C) and its own melting temperature (165°C). This is presumably due to surface melting effect in nanostructures and should be size dependent-the surface melting temperature may decrease with the diameter of nanofibrils. Therefore, some pore closing might happen even at operating temperatures, it will lead to capacity fade that is undesired for battery performance.

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