Lithium Battery Electrode Coating Structure for Peel-Resistant Adhesion
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Solution Overview
Problem
Conventional lithium secondary battery separators lack a separate adhesive layer, resulting in weak interfacial adhesive force with the counter electrode, which deteriorates battery assembly processability and leads to interfacial peeling due to electrode expansion and contraction, ultimately affecting battery life characteristics.
Innovation Solution
The electrode for lithium secondary batteries comprises an electrode substrate with a first porous layer having a porosity of 10% or less and a second porous layer containing a binder resin and inorganic fine particles, with a porosity of 30% or more. This configuration enhances adhesive force and maintains it even with electrode expansion and contraction, thereby improving battery life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous coating layer is formed on a porous substrate to provide insulation and heat shrinkage protection, then battery safety is improved, but interfacial adhesive force with the counter electrode becomes weak
Solution Approach 1:
The separator is divided into three distinct layers: a porous substrate layer, an intermediate porous coating layer for safety functions, and an outer non-porous coating layer for adhesive strength. This segmentation allows each layer to specialize in its function without compromising the others.
Solution Approach 2:
The separator uses composite material structure combining different polymer materials with distinct properties. The non-porous outer layer uses a polymer with high adhesive strength to the counter electrode, while the porous inner layers provide safety functions, creating a composite structure that achieves multiple objectives simultaneously.
2Temperature
If a porous coating layer with inorganic particles is used to enhance insulation characteristics, then heat shrinkage resistance is improved, but interfacial peeling occurs due to insufficient adhesive force
Solution Approach 1:
The separator structure separates the thermal protection function (porous layers with inorganic particles) from the adhesive function (non-porous outer layer), allowing the porous layers to focus on heat shrinkage resistance while the outer layer ensures interfacial stability during electrode expansion and contraction.
Solution Approach 2:
Different regions of the separator have different properties: the inner porous regions are optimized for thermal resistance and ion permeability, while the outer non-porous region is optimized for adhesive strength and interfacial stability, with each region's properties tailored to its specific functional requirements.
3Strength
If a non-porous structure is used to improve adhesive force, then interfacial adhesion is enhanced, but ion permeability and electrical conductivity are reduced
Solution Approach 1:
The separator is segmented into porous inner layers for ion permeability and a non-porous outer layer for adhesion, allowing ion transport through the porous structure while the non-porous layer provides the necessary adhesive strength without blocking ion pathways.
Solution Approach 2:
The separator exhibits local quality differentiation where the inner porous regions maintain high ion permeability and the outer non-porous region provides strong adhesion, with the transition between regions optimized to maintain both functions effectively.
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 electrode structure achieves excellent adhesive force and battery life characteristics by preventing interfacial peeling and maintaining low resistance characteristics through the dense structure of the first porous layer and the ion conductive properties of the second porous layer.
Implementation Method 1
a first porous layer formed on the electrode substrate, having a porosity of 10% or less
Implementation Method 2
a second porous layer formed on the first porous layer, containing a binder resin and inorganic fine particles, having a porosity of 30% or more
Data Source
AI summary
An electrode for a lithium secondary battery includes an electrode substrate with a first porous layer formed on the electrode substrate and a second porous layer formed on the first porous layer. The first porous layer has a porosity of 10% or less; and the second porous layer formed on the first porous layer has a porosity of 30% or more. The second porous layer contains a binder resin and inorganic fine particles. The manufacturing method of the same and a lithium secondary battery including the same is also provided.