Composite Separator Bonding Layer for Battery Safety
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Solution Overview
Problem
Secondary battery separators exhibit poor durability due to de-intercalation of inorganic particles in the porous coating layer, leading to safety issues and reduced mechanical strength, especially during high-temperature conditions, and insufficient bonding force with electrodes, resulting in potential internal short-circuits and decreased cycling characteristics.
Innovation Solution
A composite separator with a porous polymeric material and a porous coating layer containing inorganic particles and binder resin, where the inorganic particles are coated with binder resin for point or plane binding, and an electrode bonding layer made of particulate polymer with a glass transition temperature between −110°C to 0°C, providing improved adhesion and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous inorganic coating layer is formed by coating a mixture of inorganic particles and binder resin on a porous separator, then thermal safety is improved, but interlayer bonding force deteriorates causing electrode-separator separation
Solution Approach 1:
The coating layer is divided into two distinct functional layers: a porous inorganic coating layer for thermal safety and an electrode bonding layer for strong adhesion. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between thermal safety and bonding strength
Solution Approach 2:
The invention uses composite material structure with inorganic particles (alumina, silica, titania) combined with organic binder resin in the porous coating layer, and additionally incorporates a separate electrode bonding layer with specific resin content (1-10 wt%). This composite approach enables simultaneous achievement of thermal stability from inorganic particles and strong bonding from the optimized resin composition
2Productivity
If a porous bonding layer is formed by phase separation effect using ethanol and acetone, then infiltration and resistance are improved, but mechanical strength deteriorates due to swelling and coherence loss
Solution Approach 1:
Different regions of the separator are assigned different properties: the porous inorganic coating layer provides thermal safety with controlled porosity for ion transport, while the electrode bonding layer provides mechanical strength and adhesion. This local differentiation resolves the contradiction by allowing high infiltration in the porous layer without compromising overall mechanical integrity
Solution Approach 2:
The invention controls the resin content in the electrode bonding layer within a specific range (1-10 wt%) and uses particulate polymers with controlled glass transition temperatures (-110°C to 0°C). These parameter optimizations ensure the bonding layer provides adequate mechanical strength while maintaining necessary porosity for ion infiltration
3Temperature
If inorganic particles are used in the porous coating layer, then thermal shrinkage resistance is improved, but durability deteriorates due to de-intercalation of particles
Solution Approach 1:
The inorganic particles are pre-coated on the porous separator before final assembly, creating a stable thermal barrier layer that prevents thermal shrinkage. The subsequent addition of the electrode bonding layer further secures the structure, preventing particle de-intercalation during battery operation and maintaining long-term durability
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 enhances the bonding force between the electrode and separator, prevents de-intercalation of inorganic particles, and maintains low interfacial resistance, resulting in improved output and life characteristics of electrochemical elements.
Implementation Method 1
an entirety or portion of a surface of the inorganic particles being coated with the binder resin, and thus the particles are integrated by point binding and/or plane binding
Implementation Method 2
the electrode bonding layer includes a particulate polymer having adhesive characteristics
Data Source
AI summary
The present disclosure relates to a composite separator for an electrochemical element and the electrochemical element including the same. More specifically, the present disclosure relates to a separator with excellent durability and improved formation of a bonding layer of a thin film and improved bonding force with an electrode, and a method for manufacturing the same. Further, the present disclosure pertains to an electrochemical element comprising the aforementioned separator.