Core-Shell Composite Separator for Battery Adhesion Without Pore Blockage
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Solution Overview
Problem
Conventional secondary batteries face issues with weak binding forces between electrodes and separators, leading to separation and alignment disturbances, and the use of high amounts of polymer resin to enhance adhesiveness results in performance degradation due to polymer dissolution and pore blockage.
Innovation Solution
A composite separator featuring a porous substrate with a core-shell type polymer fiber adhesive layer, where the shell has a glass transition temperature of 60°C or higher and the core has a lower glass transition temperature, providing adhesive strength under pressure and temperature conditions, while the shell acts as a protective layer to prevent unintended adhesion during storage and transportation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large amount of polymer resin is added to improve adhesive performance, then adhesiveness between electrode and separator is improved, but battery performance degrades due to polymer dissolution and pore blockage
Solution Approach 1:
The adhesive layer is segmented into core-shell type polymer fibers where the core provides adhesion and the shell provides protection. This segmentation allows the adhesive polymer to be protected from electrolyte contact while maintaining its bonding function, resolving the contradiction between adhesiveness and battery performance reliability
Solution Approach 2:
The invention uses composite materials by combining two different polymers with complementary properties: one polymer for adhesion (lower Tg) and another for protection (higher Tg). This composite structure enables the adhesive layer to simultaneously provide strong bonding and resist electrolyte dissolution, solving the technical contradiction
2Strength
If polymer resin is used to enhance adhesiveness, then binding force between electrode and separator is improved, but the polymer swells and blocks pore layer in separator
Solution Approach 1:
The shell polymer acts as an intermediary protective layer between the adhesive core polymer and the electrolyte. It prevents direct contact between the adhesive polymer and electrolyte, thereby preventing swelling and pore blockage while allowing the core to maintain strong binding force to the electrode
Solution Approach 2:
The shell forms a flexible protective film around the core polymer fibers. This thin film structure provides protection against electrolyte-induced swelling and pore blockage while maintaining the overall flexibility and adhesive functionality of the adhesive layer
3Strength
If adhesive material is used to improve binding, then adhesion between electrode and separator is enhanced, but alignment is disturbed and separation occurs
Solution Approach 1:
The invention optimizes the glass transition temperature parameter of the polymers used. The core polymer has lower Tg for good adhesion, while the shell polymer has higher Tg for dimensional stability. This parameter optimization allows strong adhesion without causing alignment disturbance or separation
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 composite separator maintains high adhesiveness and prevents electrolyte elution, allowing for higher capacity and larger battery sizes by effectively adhering to electrodes and accommodating swelling, thus maintaining battery alignment.
Implementation Method 1
the adhesive layer which is provided on at least any one surface of the porous substrate and includes a core-shell type polymer fiber... the adhesive layer may have adhesive strength generated by the polymer included in the core at a pressure of 3 kgf/cm 2
Implementation Method 2
the core-shell type polymer fiber may include a polymer having a glass transition temperature of 60°C or higher in the shell... the shell acts as a protective layer to prevent unintended adhesion during storage and transportation
Implementation Method 3
a porous substrate... the porous substrate may include a porous polyolefin polymer film
Data Source
Figure 1~2
AI summary
Provided are a composite separator including: a porous substrate, and an adhesive layer which is provided on at least any one surface of the porous substrate and includes a core-shell type polymer fiber, and a secondary battery including the same.