Separator for electrochemical device containing organic / inorganic composite porous coating layer and electrochemical device containing the same

The use of a PVDF-based and acrylic polymer composite coating on electrochemical device separators addresses adhesion issues, ensuring strong bonding in both dry and wet states, enhancing safety and performance.

JP7744080B2Active Publication Date: 2025-09-25LG ENERGY SOLUTION LTD
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Patent Information

Application Number
JP2023575467
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2021-10-29
Filing Date
2022-10-18
Publication Date
2025-09-25
Estimated Expiration
2042-10-18

AI Technical Summary

Technical Problem

Existing separators for electrochemical devices face issues with insufficient adhesion between electrodes in both dry and wet states, leading to potential separation and local defects due to inorganic particle detachment, which compromises safety and stability.

Method used

A separator comprising a polyolefin-based polymer substrate with an organic/inorganic composite porous coating layer containing a mixture of polyvinylidene fluoride (PVDF)-based and acrylic polymers, where the PVDF polymer has a Hansen Solubility Parameter (HSP) of 13 or less, ensuring strong adhesion in both dry and wet conditions.

Benefits of technology

The separator maintains high adhesive strength and durability, preventing inorganic particle detachment, improving thermal safety and insulating properties while maintaining ionic conduction, thus enhancing the performance and lifespan of electrochemical devices.

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Abstract

The separator according to the present invention contains a particulate binder resin containing a mixture of an acrylic binder and a PVDF binder in the organic / inorganic composite porous coating layer, and has excellent adhesive strength with the electrode in both dry and wet states. Therefore, in a continuous roll-to-roll process in which an electrode assembly is manufactured by laminating an electrode and a separator, the shape stability and processability of the electrode assembly are improved. In addition, when a battery is manufactured using an electrode assembly including the separator, a high binding strength can be maintained between the separator and the electrode even when the battery is immersed in an electrolyte, and the interface resistance characteristics are not reduced. In addition, since the binder resin particles maintain a high adhesive strength in both dry and wet states, the inorganic particles contained in the organic / inorganic composite porous coating layer are well fixed without being detached, and the shape stability of the separator can be improved. Therefore, the heat resistance safety and insulation properties of the battery are improved. In addition, since the porous coating layer has a porous structure due to the interstitial volume between the particles, it does not interfere with ion conduction between the electrode and the separator, and has a low resistance increase rate and excellent life characteristics.
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Citation Information

Patent Citations

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    CN1851957A

  • Electrode for lithium secondary battery and lithium secondary battery using the same

    JP2012182012A

  • Nonaqueous electrolyte secondary battery

    JP2016115593A

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    JP2018163872A

  • Separator for nonaqueous secondary battery, nonaqueous secondary battery, method for manufacturing separator for nonaqueous secondary battery, and coating composition for nonaqueous secondary battery

    JP2019029314A