Laminated Porous Separator with Filler Particle Distribution
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries with conventional separators have insufficient high-current discharge characteristics and lack high heat-resistance, which limits their performance in high-energy output applications.
Innovation Solution
A laminated porous film separator with a heat-resistant layer containing a nitrogen-containing aromatic polymer and a shut-down layer made of thermoplastic resin, where the heat-resistant layer includes two or more fillers with specific particle size ratios and distributions, enhancing both heat-resistance and ion permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a polyethylene film with a polyamide heat-resistant layer is used as a separator, then heat-resistance is improved, but high-current discharge characteristic deteriorates
Solution Approach 1:
The invention changes the particle size parameters of the filler from a single size to a specific distribution pattern (D10-D90 range of 3-10 μm with D50 of 6-8 μm), which transforms the pore structure characteristics to simultaneously achieve heat-resistance and improved high-current discharge performance
Solution Approach 2:
The invention creates a composite heat-resistant layer combining polyamide resin with specifically sized filler particles (D10-D90: 3-10 μm, D50: 6-8 μm), where the composite structure provides both thermal stability and optimized ion transport pathways for high-current discharge
2Temperature
If the heat-resistant layer thickness is increased to improve heat-resistance, then high-current discharge characteristic deteriorates
Solution Approach 1:
The invention optimizes the thickness parameter to a specific range (1-10 μm) and combines it with controlled filler particle size distribution, transforming the layer's internal structure to provide sufficient heat-resistance while maintaining ion permeability for high-current discharge
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 high-current discharge characteristics and high heat-resistance, making it suitable for high-energy output applications such as automotive batteries and power tools, while maintaining reliability and safety.
Implementation Method 1
the heat-resistant layer further comprises two or more fillers, and the value of D2/D1 is 0.15 or less... D1 is not less than 0.1 μm, and D2 is less than 0.1 μm
Implementation Method 2
A separator comprises a porous film having micropores... it is required to shut-down the current (to plug the micropores of the porous film) at a temperature as low as possible
Data Source
AI summary
Provided is a separator made of a laminated porous film in which a heat-resistant layer that comprises a heat-resistant resin and a shut-down layer that comprises a thermoplastic resin are laminated, wherein the heat-resistant layer further comprises two or more fillers, and the value of D2/D1 is 0.15 or less where among values each obtained by measuring the average particle diameter of particles that constitute one of the two or more fillers, the largest value is let be D1 and the second largest value is let be D2.