Separator Coating Structure for Wet-Adhesion Battery Electrodes
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Solution Overview
Problem
Existing separators for electrochemical devices face challenges in maintaining adhesive strength, particularly when exposed to electrolyte solutions, due to the migration of polymer binder and inorganic particles during the drying process.
Innovation Solution
A separator design featuring a porous coating layer with specific distribution of first and second binder particles and inorganic particles, where the inorganic particles are dispersed in a first surface region facing the porous polymer substrate, and the second binder particles are dispersed in a second surface region opposite to the first surface region, ensuring both dry and wet adhesive strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the polymer binder and inorganic particles are applied as a slurry and dried, then the porous coating layer is formed, but the polymer binder and inorganic particles migrate during drying, causing poor adhesive strength
Solution Approach 1:
The patent applies local quality by creating distinct regions within the porous coating layer: a first region containing inorganic particles and first binder particles for structural support, and a second region containing second binder particles with higher adhesive strength for bonding to the electrode. This spatial differentiation of particle properties and distribution resolves the contradiction by ensuring both uniform distribution during manufacturing and high adhesive strength in the final product.
Solution Approach 2:
The patent uses composite materials by combining multiple types of binder particles (first binder particles and second binder particles with different properties) and inorganic particles in specific ratios and distributions. The composite structure allows the slurry to be uniformly applied while the differentiated particle composition ensures high adhesive strength after drying, resolving the migration issue.
2Stability of the object's composition
If the polymer binder particles are smaller than inorganic particles, then the coating layer structure is maintained, but the binder particles cannot migrate to the surface region, resulting in insufficient adhesive strength
Solution Approach 1:
The patent resolves this contradiction by creating local quality differences: the first binder particles are distributed in the first region to maintain structural stability, while the second binder particles are concentrated in the second region (surface region) to provide high adhesive strength. This spatial differentiation allows small binder particles to remain structurally stable while still achieving sufficient surface adhesion.
Solution Approach 2:
The patent applies parameter changes by varying the particle size, density, and adhesive properties of different binder particles. The second binder particles have different characteristics from the first binder particles, allowing them to migrate to the surface region and provide high adhesive strength while the first binder particles maintain the overall coating layer structure.
3Reliability
If the separator is bonded to the electrode with a porous coating layer, then thermal shrinkage is prevented, but the adhesive strength deteriorates when electrolyte solution is injected
Solution Approach 1:
The patent resolves this contradiction by creating local quality differentiation in the porous coating layer: the first region contains inorganic particles and first binder particles that provide thermal stability and prevent shrinkage, while the second region contains second binder particles with high adhesive strength that maintain bonding even when electrolyte solution is injected. This spatial differentiation allows both thermal shrinkage prevention and wet adhesive strength to be achieved simultaneously.
Solution Approach 2:
The patent uses composite materials by combining inorganic particles with multiple types of binder particles having different properties. The composite structure provides both thermal stability (from inorganic particles and first binder particles) and high wet adhesive strength (from second binder particles), resolving the contradiction between thermal shrinkage prevention and adhesive strength maintenance.
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 proposed separator achieves excellent adhesive strength to the electrode both in dry and wet states, effectively preventing peeling off during electrolyte injection and maintaining the integrity of the electrochemical device.
Implementation Method 1
The porous coating layer including the polymer binder and the inorganic particles may prevent thermal shrinkage of the porous polymer substrate.
Implementation Method 2
Since the solvent volatilizes during the application and drying of the slurry, the polymer binder and the inorganic particles may migrate.
Implementation Method 3
The inorganic particles may be connected to other inorganic particles by the polymer binder to form an interstitial volume
Implementation Method 4
lithium ions may move through the interstitial volume
Data Source
AI summary
A separator for an electrochemical device including a porous polymer substrate and a porous coating layer on at least one side of the porous polymer substrate. The porous coating layer includes first binder particles, second binder particles, and inorganic particles. The inorganic particles are mostly dispersed in a first surface region of the porous coating layer, and the second binder particles are mostly dispersed in a second surface region of the porous polymer substrate, in which the first surface region faces the porous polymer substrate and the second surface region is an opposite surface region to the first surface region. The inorganic particles have a larger weight per particle than each respective weight per particle of the first and second binder particles.