Laminated Separator for Non-Aqueous Battery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
It has been difficult for thin nonaqueous electrolyte secondary battery laminated separators to simultaneously achieve sufficient piercing strength, shutdown characteristics, and air permeability.
Innovation Solution
The degree of kneading in the resin composition for producing the porous film is improved, resulting in a laminated separator with a polyolefin component content of at least 80% by volume, a specific thickness range, and a porous layer with a filler content of 50-99% by mass, which satisfies specific piercing strength and Gurley value criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the separator is made thinner to reduce battery size, then the battery size is reduced, but the piercing strength becomes insufficient
Solution Approach 1:
The patent uses a laminated structure combining a heat-resistant porous layer and a polyolefin porous film layer. This composite structure allows the separator to maintain thin dimensions while achieving sufficient piercing strength through the synergistic combination of materials with different functional properties.
Solution Approach 2:
The patent applies different material properties to different layers: the heat-resistant porous layer provides high-temperature stability and structural support, while the polyolefin porous film layer provides shutdown function and ion permeability. This local differentiation of material qualities enables the thin separator to meet multiple performance requirements simultaneously.
2Power
If the separator is made thinner to improve output characteristic, then the output characteristic is improved, but the shutdown characteristic becomes insufficient
Solution Approach 1:
The laminated structure combines materials with complementary functions: the polyolefin porous film layer provides the shutdown function by melting at elevated temperatures to close pores, while the heat-resistant porous layer maintains structural integrity. This composite approach enables thin separators to retain adequate shutdown characteristics.
Solution Approach 2:
The patent controls the thickness of each layer within specific ranges (heat-resistant porous layer: 1-10 μm, polyolefin porous film layer: 3-20 μm) to optimize the balance between output characteristic and shutdown characteristic. By adjusting these dimensional parameters, the separator achieves both high power density and reliable shutdown function.
3Volume of moving object
If the separator is made thinner to reduce battery size, then the battery size is reduced, but the air permeability becomes insufficient
Solution Approach 1:
The patent employs porous structures in both layers with controlled porosity (heat-resistant porous layer: 30-80%, polyolefin porous film layer: 30-80%). These porous structures enable adequate air permeability and ion transport even in thin separators, allowing reduced battery size without compromising electrolyte distribution and thermal management.
Solution Approach 2:
The laminated composite structure combines two porous materials with different pore characteristics, creating a synergistic effect where the overall air permeability is sufficient despite the reduced total thickness. The composite structure maintains adequate fluid transport pathways while minimizing separator thickness.
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 solution enables a thin, high-air-permeability separator with excellent shutdown characteristics and physical strength, enhancing both safety and output performance in nonaqueous electrolyte secondary batteries.
Implementation Method 1
Such a porous film is melted and made non-porous in the event of abnormal heat generation to block the ion passage for prevention of further heat generation
Implementation Method 2
a nonaqueous electrolyte secondary battery laminated separator including a laminated porous film
Data Source
AI summary
Provided is a nonaqueous electrolyte secondary battery laminated separator including a laminated porous film including a porous film and a porous layer. The piercing strength (S) of the laminated porous film satisfies Formula (1): 2 gf≦Sp−S≦25 gf, and the piercing strength (Sp) of the porous film after removal of the porous layer from the laminated porous film satisfies Formula (2): 300 gf≦S≦400 gf. The nonaqueous electrolyte secondary battery laminated separator is excellent in output characteristic, shutdown characteristic, and piercing strength.