Composite Battery Separator With Anti-Blocking Electrode Adhesion
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Solution Overview
Problem
Existing separators in secondary batteries, particularly those with a porous ceramic layer, suffer from inadequate adhesion to electrodes, leading to misalignment and potential short circuits, which can cause safety issues like fires due to local resistance and physical damage during cell assembly.
Innovation Solution
A composite separator with an adhesive layer containing a particulate organic binder is introduced, providing excellent electrode adhesion and preventing blocking, even under high temperatures, by ensuring the adhesive strength meets specific criteria and maintaining alignment during battery assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a porous ceramic layer is formed on the porous substrate to improve heat resistance, then thermal stability is improved, but adhesion to the electrode deteriorates
Solution Approach 1:
An adhesive layer is introduced as an intermediary between the porous ceramic layer and the electrode. This adhesive layer contains a particulate organic binder that provides strong bonding to the electrode while the porous ceramic layer maintains its heat resistance properties. The adhesive layer acts as a mediator that resolves the conflict between thermal stability and adhesion strength.
Solution Approach 2:
The separator is constructed as a composite structure with multiple layers: a porous substrate, a porous ceramic layer for heat resistance, and an adhesive layer with particulate organic binder for strong electrode adhesion. This composite material approach allows each layer to fulfill its specific function, achieving both high temperature stability and strong adhesion simultaneously.
2Manufacturing precision
If adhesive strength is increased to prevent misalignment, then alignment precision is improved, but blocking during winding occurs
Solution Approach 1:
The adhesive layer uses a particulate organic binder with specific physical properties, including controlled glass transition temperature and particle size distribution. By optimizing these parameters, the adhesive provides sufficient strength for alignment during assembly but maintains flexibility and anti-blocking properties during the winding process, preventing the harmful blocking effect.
3Reliability
If a porous ceramic layer is added to improve safety, then reliability is improved, but device complexity increases
Solution Approach 1:
The separator is segmented into distinct functional layers: a porous substrate providing mechanical support, a porous ceramic layer providing heat resistance and safety, and an adhesive layer providing electrode bonding. This segmentation allows each layer to be optimized for its specific function while maintaining overall simplicity through a systematic multi-layer architecture.
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 ensures strong adhesion to electrodes, prevents blocking, maintains alignment, and provides uniform lithium ion conductivity, enhancing battery performance and safety by reducing the risk of short circuits and improving capacity retention.
Implementation Method 1
an adhesive layer formed on one surface or both surfaces of a porous separator
Implementation Method 2
capable of resolving the problems in the related art in a case where blocking does not occur when adhesive layers are brought into contact with each other, pressurized at a temperature of 50° C. and a pressure of 1.7 MPa for 2 hours, and then peeled at a speed of 300 mm/min and an angle of 180°
Data Source
AI summary
A composite separator including an adhesive layer and a secondary battery including the same. In the composite separator, the adhesive layer contains a particulate organic binder having a glass transition temperature of 60 to 80° C., and when the adhesive layers are brought into contact with each other, pressurized at a temperature of 50° C. and a pressure of 1.7 MPa for 2 hours, and then peeled at a speed of 300 mm/min and an angle of 180°, blocking does not occur between the adhesive layers, and an adhesive strength to a positive electrode is 5 gf/cm or more.