Electrode Adhesive Separator Layer That Preserves Battery Porosity
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Solution Overview
Problem
Existing separators for electrochemical devices face challenges in achieving improved close contact and adhesion to electrodes while preventing pore blocking and infiltration, especially when the particles forming the electrode adhesive layer are smaller than the pores of the underlying substrate.
Innovation Solution
A separator is designed with a porous polymer substrate and an electrode adhesive layer comprising organic particles and an acrylic resin binder. The organic particles have an average diameter smaller than the pores of the substrate, and the acrylic resin binder is present in a specific weight percentage to ensure adequate adhesion and air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an electrode adhesive layer is formed on the separator to improve adhesion to the electrode, then the bindability between electrode and separator is improved, but the pores of the separator are blocked and air permeability is reduced
Solution Approach 1:
The electrode adhesive layer is designed with a porous structure having controlled porosity (30-70%) and specific pore size (0.1-10 μm) to maintain gas permeability while providing adhesion. The porous structure allows air and electrolyte to pass through while the adhesive layer prevents electrode detachment.
Solution Approach 2:
The adhesive layer uses a composite formulation combining polymer binder (3-20 parts by weight) with inorganic particles (70-95 parts by weight) and optional conductive additives. This composite structure provides both adhesive functionality and controlled porosity to prevent pore blocking.
2Strength
If particles forming the electrode adhesive layer have small diameter to improve adhesion, then close contact with electrode is improved, but particles infiltrate into the pores of the separator
Solution Approach 1:
The particle diameter is controlled within a specific range (0.1-10 μm) and the porosity of the adhesive layer is optimized (30-70%) to create a balance where particles are small enough for good contact but the porous structure prevents infiltration into separator pores, maintaining low electrical resistance.
Solution Approach 2:
The adhesive layer has non-uniform pore distribution with different pore sizes and densities at different locations - larger pores near the separator interface to prevent infiltration, and smaller pores at the electrode interface for better contact, creating localized properties that solve both problems.
3Strength
If the electrode adhesive layer is made thicker to improve adhesion, then binding strength is improved, but the air permeability and ion transport are reduced
Solution Approach 1:
The thickness of the electrode adhesive layer is controlled within a specific range (1-10 μm) to provide sufficient adhesion strength while maintaining adequate porosity (30-70%) throughout the layer thickness to ensure ion transport and air permeability are not significantly reduced.
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 separator effectively prevents pore blocking and infiltration, while achieving high adhesion to electrodes, thereby enhancing the safety and performance of electrochemical devices such as lithium secondary batteries.
Implementation Method 1
an electrode adhesive layer formed on at least one surface of the porous polymer substrate and including organic particles and an acrylic resin binder
Data Source
Figure 1a~1b
Figure 2a
Figure 2b
AI summary
Disclosed are a separator having an electrode adhesive layer and an electrochemical device including the same. The electrode adhesive layer includes organic particles and an acrylic resin binder. Preferably, the acrylic resin binder is present in an amount of 30 wt% or more, so that a film-shaped electrode adhesive layer can be formed even when the organic particles have a particle diameter smaller than that of the pores of the underlying substrate or voids of the underlying porous coating layer.