Battery Separator Coating for High-Temperature Wet Stability
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Solution Overview
Problem
Lithium secondary battery separators experience significant dimensional instability and adhesive strength reduction in high-temperature wet states due to low polymer binder content, leading to reduced performance and reliability.
Innovation Solution
A separator design incorporating a porous polymer substrate with a porous coating layer containing a water-based polymer binder, inorganic particles, and an organic filler, where the organic filler has a higher glass transition temperature than the binder, providing enhanced adhesive strength and dimensional stability within the operating temperature range of 90°C to 130°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the polymer binder content in the porous coating layer is reduced to lower cost and improve ion permeability, then the adhesive strength between electrodes and separator decreases, but this leads to significant dimensional instability and shrinkage in high-temperature wet states
Solution Approach 1:
The patent applies composite materials by combining organic filler particles with inorganic particles in the porous coating layer. The organic filler forms a three-dimensional network structure that works synergistically with inorganic particles to provide both adhesive strength and dimensional stability, allowing reduced polymer binder content while maintaining reliability in high-temperature wet states.
Solution Approach 2:
The patent implements local quality by creating a porous coating layer with specific local characteristics - the organic filler and inorganic particles are distributed to form interstitial volumes with controlled pore sizes (0.01-10 μm). This local structural optimization ensures adequate adhesive strength and dimensional stability in critical areas while maintaining overall ion permeability.
2Ease of manufacture
If the polymer binder content is reduced to improve ion permeability and reduce cost, then manufacturing cost decreases, but the adhesive strength between electrodes and separator is insufficient under high temperature conditions
Solution Approach 1:
The patent uses composite materials comprising organic filler and inorganic particles that together provide adequate adhesive strength at high temperatures. This composite structure reduces the required polymer binder content, thereby lowering manufacturing costs while maintaining necessary adhesive properties through the synergistic three-dimensional network formation.
Solution Approach 2:
The patent employs porous materials with controlled pore sizes (0.01-10 μm) formed by the interstitial volumes between organic filler and inorganic particles. This porous structure improves ion permeability and reduces material requirements, leading to cost reduction while maintaining adhesive strength through optimized pore architecture rather than relying solely on polymer binder quantity.
3Force
If the porous coating layer uses minimal polymer binder to improve air permeability and ion transport, then air permeability increases, but the separator exhibits significant shrinkage when impregnated with electrolyte at high temperatures
Solution Approach 1:
The patent applies local quality by optimizing the pore size distribution (0.01-10 μm) in the porous coating layer to balance air permeability and dimensional stability. The organic filler and inorganic particles create localized three-dimensional network structures that maintain structural integrity during electrolyte impregnation, preventing shrinkage while preserving adequate ion transport pathways.
Solution Approach 2:
The patent uses composite materials where organic filler and inorganic particles work together to form a stable porous structure. This composite architecture provides both sufficient air permeability for ion transport and dimensional stability when the separator is impregnated with electrolyte, eliminating the need for high polymer binder content.
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 maintains excellent adhesive strength and dimensional stability even in high-temperature wet conditions, ensuring reliable performance and reduced shrinkage rates, thereby improving the overall efficiency and longevity of lithium secondary batteries.
Implementation Method 1
the organic filler has a higher glass transition temperature than the binder, providing enhanced adhesive strength and dimensional stability within the operating temperature range of 90°C to 130°C
Implementation Method 2
The porous coating layer including a polymer binder and an inorganic particle can prevent thermal shrinkage of the porous polymer substrate
Implementation Method 3
an inorganic particle may be connected to another inorganic particle by a polymer binder to form an interstitial volume, and lithium ions can move through the interstitial volume
Implementation Method 4
the polymer binder can impart an adhesive strength to the porous coating layer, and the porous coating layer can be attached to the porous polymer substrate and electrodes, respectively
Implementation Method 5
the separator including the porous coating layer exhibits excellent dimensional stability in a dry state without an electrolyte
Data Source
AI summary
Disclosed is a separator for an electrochemical device including a porous polymer substrate and a porous coating layer at least one side of the porous polymer substrate, wherein the porous coating layer includes a water-based polymer binder, an inorganic particle, and an organic filler, and in the organic filler, adhesive strength is generated in the range of the operating temperature of the electrochemical device.