Battery Separator Coating to Limit Particle Agglomeration Pressure
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Solution Overview
Problem
Existing electrochemical device separators suffer from non-homogeneous distribution of inorganic particles in the coating layer, leading to aggregation and localized pressure application, which can cause short-circuits and reduced dielectric breakdown performance.
Innovation Solution
A separator design with a low content of secondary particles in the inorganic coating layer, achieved by uniformly distributing inorganic particles and using a binder resin to maintain adhesion and prevent aggregation, ensuring a high dielectric breakdown voltage and uniform pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separator is directly inserted between electrodes during assembly, then assembly simplicity is improved, but the separator may contact the electrode edge and cause a short circuit
Solution Approach 1:
The extension part of the separator is inserted into the groove formed by the electrode edge and the outer case, creating a nested structure that prevents the separator from contacting the electrode edge while maintaining assembly simplicity
Solution Approach 2:
The groove acts as an intermediary space between the separator and electrode edge, allowing the separator extension to be positioned without directly contacting the electrode, thus preventing short circuits
2Area of stationary object
If the separator has a larger size to cover the electrode area, then coverage is improved, but the risk of contacting electrode edges increases
Solution Approach 1:
The separator extension is nested within the groove structure, allowing the separator to cover the necessary electrode area while the groove prevents contact with electrode edges
3Strength
If the separator material is made more robust to prevent deformation, then mechanical strength is improved, but radial expansion during swelling is restricted
Solution Approach 1:
The separator is functionally segmented into a main body portion and an extension portion, where the extension part provides mechanical support in the groove while the main body can still expand radially during swelling
Data Source
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AI summary
Disclosed is a separator for an electrochemical device having a low content of secondary particles formed by aggregation of an inorganic particles in the inorganic coating layer. Particularly, the separator has a low content of secondary particles protruding from the separator surface to a predetermined height or more. Since the inorganic particles are not aggregated but are distributed homogeneously in the inorganic coating layer, the separator allows uniform dispersion of pressure over the whole surface of the separator, when it is applied to a battery and pressure is generated in the battery due to the charge/discharge of the battery. In this manner, it is possible to minimize deformation of the separator. Meanwhile, when using a porous film made of a polymer material as a separator substrate, there is a low tendency for intensive application of pressure from the secondary particles to a local site of the separator substrate, and thus the separator substrate is less damaged and a possibility of short-circuit generation is reduced.