Microporous Separator Coating for Electrode Adhesion and Heat Stability
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Solution Overview
Problem
Existing separators for power storage devices face issues with uneven adhesive force distribution, poor heat resistance, and insufficient binding force, leading to potential short circuits and deformation during charging cycles.
Innovation Solution
A separator with a polyolefin microporous membrane substrate and a covering layer composed of inorganic filler and thermoplastic polymer particles, where the polymer particles protrude to at least 0.1 times the thickness of the inorganic filler portion, and the covering layer is formed in an inclined manner to enhance adhesive force and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a covering layer with adhesive polymer is disposed on the separator to increase adhesion between separator and electrodes, then adhesive force is improved, but manufacturing complexity increases due to additional coating steps
Solution Approach 1:
The patent combines the inorganic filler layer and adhesive polymer layer into a single integrated covering layer formed by one coating process. The adhesive polymer is mixed with inorganic filler particles to create a composite coating material that is applied in a single step, eliminating the need for separate coating operations while achieving both heat resistance and adhesion enhancement.
Solution Approach 2:
The covering layer is formed as a composite material consisting of inorganic filler particles dispersed in an adhesive polymer matrix. This composite structure provides both the heat resistance characteristics of inorganic materials and the adhesive properties of the polymer, achieving multiple functions in a single layer without requiring multiple sequential coating steps.
2Strength
If secondary coating of adhesive layer is performed to enhance bonding strength, then adhesive force is improved, but manufacturing time increases
Solution Approach 1:
The adhesive polymer is pre-mixed with inorganic filler particles to create a composite coating material before application. This preliminary preparation ensures that the adhesive properties and heat resistance are integrated in advance, eliminating the need for subsequent secondary coating operations to achieve adequate bonding strength.
3Temperature
If inorganic filler-containing heat-resistant layer is added to separator, then heat resistance is improved, but adhesive force with electrodes deteriorates
Solution Approach 1:
The covering layer is formulated as a composite where inorganic filler particles are dispersed within an adhesive polymer matrix. The inorganic particles provide heat resistance while the polymer continuous phase maintains adhesive properties, allowing both functions to coexist in a single integrated layer without requiring separate functional layers.
Solution Approach 2:
The inorganic filler particles are distributed throughout the covering layer to provide localized heat resistance, while the adhesive polymer matrix continuously binds the particles and provides overall adhesive functionality. This local differentiation of functions within a homogeneous structure allows simultaneous achievement of heat resistance and adhesion.
4Strength
If polymer particles are dispersed in inorganic particles with protruding structure, then adhesive force is improved, but manufacturing precision decreases due to uneven distribution
Solution Approach 1:
The covering layer is formed as a composite coating material where adhesive polymer and inorganic filler particles are uniformly mixed together before application. This pre-mixing approach ensures homogeneous distribution of both components throughout the coating layer, avoiding the thickness non-uniformity that would result from layering or protruding structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a separator with high adhesive force and low heat shrinkage, preventing short circuits and maintaining structural integrity during temperature changes, thus improving the safety and performance of power storage devices.
Implementation Method 1
a covering layer that comprises a thermoplastic polymer exhibiting an adhesive function under prescribed conditions, in order to increase adhesion between the separator and the electrodes
Implementation Method 2
the polymer particles protrude from the covering layer, to at least 0.1 times the thickness of the inorganic filler portion of the covering layer
Implementation Method 3
obtaining satisfactory thermal stability performance and a satisfactory adhesive effect with electrodes, to thus ensure safety and flatness for a power storage device
Implementation Method 4
allowing ions to pass through the electrolyte solution that is held in the micropores
Data Source
AI summary
The present disclosure provides: a separator which is for a power storage device and has high adhesive force to an electrode and a small thermal shrinkage rate; and a power storage device including the same. A separator for a power storage device according to the present disclosure comprises: a base material of a polyolefin microporous film; and a coating layer disposed on at least one surface of the base material, wherein the coating layer contains an inorganic filler and a particulate polymer protruding to a position that corresponds to at least 0.1 times the thickness of the coating layer. The separator for a power storage device has one or more among the following characteristics: the coating layer is formed into an inclined shape so that the thickness of the coating layer increases toward the protruded particulate polymer; at least 20% of the protruded particulate polymer is in contact with the surface of the base material; the 180° peel strength of the coating layer from the base material is at least 200 gf/cm; the average number of adjacent protruded particulate polymers is less than 2; and the ratio of the average particle diameter of the protruded particulate polymer to the average particle diameter of the inorganic filler is greater than 10.