Battery Separator Adhesive Layer for Low Resistance and Electrode Adhesion
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Solution Overview
Problem
Existing secondary battery separators face issues with insufficient adhesion to electrodes and increased resistance due to the use of porous coating layers containing inorganic particles, leading to potential separation of electrodes and deterioration of battery performance.
Innovation Solution
A separator design featuring a porous polymer substrate with a porous coating layer containing inorganic particles and a two-layer adhesive layer, where the second layer has a larger average pore size than the first layer, ensuring adhesion to the electrode while minimizing contact area and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a porous coating layer containing inorganic particles is used on the separator, then thermal stability is improved, but adhesion to electrodes deteriorates
Solution Approach 1:
The adhesive layer is divided into two distinct layers: a first adhesive layer in contact with the porous coating layer, and a second adhesive layer facing the electrode. This segmentation allows each layer to perform its specific function - the first layer provides thermal stability through inorganic particles, while the second layer ensures electrode adhesion through optimized polymer composition and pore structure.
Solution Approach 2:
Different regions of the adhesive layer are given different properties. The first adhesive layer contains inorganic particles for thermal stability, while the second adhesive layer has larger pore size and different polymer composition for optimal electrode contact and adhesion. This local differentiation resolves the contradiction between thermal stability and adhesion.
2Stability of the object's composition
If a porous coating layer containing inorganic particles is used on the separator, then thermal stability is improved, but resistance increases
Solution Approach 1:
The adhesive layer is segmented into two layers with different functions. The first layer contains inorganic particles for thermal stability, while the second layer has optimized pore structure with larger pore size to reduce resistance and facilitate lithium ion transport, thus resolving the contradiction between thermal stability and resistance.
Solution Approach 2:
The second adhesive layer is designed with larger pore size to create efficient pathways for lithium ion transport. This porous structure reduces resistance while the first layer maintains thermal stability, allowing the separator to achieve both thermal stability and low resistance through the combined structure.
3Reliability
If binder polymer is coated on the separator to improve adhesion, then adhesion to electrodes is improved, but resistance increases due to polymer migration
Solution Approach 1:
The adhesive layer is divided into two layers to separate the functions of adhesion and ion transport. The first layer provides adhesion through binder polymer coating, while the second layer with larger pores facilitates ion transport with reduced resistance, resolving the contradiction between adhesion improvement and resistance increase.
Solution Approach 2:
Different regions of the adhesive layer have different properties: the first layer has binder polymer for adhesion, while the second layer has larger pore size and optimized composition for low resistance. This local quality differentiation allows the system to achieve both good adhesion and low resistance simultaneously.
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 provides improved thermal stability, adhesion to electrodes, and reduced resistance, enhancing the performance and safety of secondary batteries by facilitating lithium ion propagation and minimizing contact area.
Implementation Method 1
facilitating lithium ion propagation
Implementation Method 2
improved thermal stability
Data Source
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AI summary
The present disclosure relates to a separator for a secondary battery, including: a porous polymer substrate; a porous coating layer formed on at least one surface of the porous polymer substrate, and including a plurality of inorganic particles and a first binder polymer for interconnecting and fixing the inorganic particles; and an adhesive layer formed on the top surface of the porous coating layer and including a second binder polymer, wherein the adhesive layer includes a first layer that is in contact with the top surface of the porous coating layer, and a second layer integrated with the first layer and facing an electrode, and the second layer has an average pore size larger than the average pore size of the first layer. The separator for a secondary battery can improve the problem related with resistance, while ensuring adhesion to an electrode.