Polyolefin Separator Puncture Strength and T/M Ratio Control
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries experience deformation and force issues during charge/discharge cycles, leading to non-uniformity in electrode distance and deterioration of battery characteristics due to electrode expansion and shrinkage, which affects the separator's plane direction-uniformity and electrode mix uniformity.
Innovation Solution
A nonaqueous electrolyte secondary battery with a polyolefin porous film having a puncture strength of at least 26.0 gf/g/m2, and positive and negative electrode plates with specific critical load distance ratios in a scratch test, ensuring the ratios fall within certain ranges to maintain battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional separator is used, then the battery structure is simple, but the plane direction-uniformity in distance between electrodes deteriorates due to separator deformation and force during electrode expansion and shrinkage
Solution Approach 1:
The invention changes the physical parameters of the separator by specifying a puncture strength of at least 26.0 gf/g/m2 and controlling the critical load distance ratios (T/M) within specific ranges (0.00-0.54 for separator, 0.00-0.50 for electrodes). These parameter changes enable the separator to maintain its structural integrity and uniformity during electrode expansion and shrinkage, resolving the contradiction between simple structure and manufacturing precision.
2Ease of manufacture
If conventional separator and electrode materials are used, then the manufacturing process is easy, but the uniformity within electrode mix deteriorates during charge/discharge
Solution Approach 1:
The invention controls the mechanical properties of both separator and electrodes by specifying puncture strength and critical load distance ratios within defined ranges. This ensures that all components expand and shrink at compatible rates during charge/discharge cycles, maintaining uniformity within the electrode mix while keeping the manufacturing process straightforward.
3Manufacturing precision
If the separator has high puncture strength and controlled critical load distance ratio, then the plane direction-uniformity is maintained, but the manufacturing requirements become more stringent
Solution Approach 1:
The invention establishes specific parameter ranges (puncture strength ≥26.0 gf/g/m2, T/M ratio of 0.00-0.54 for separator, 0.00-0.50 for electrodes) that balance manufacturing precision with practical manufacturability. These quantified parameters provide clear manufacturing targets while ensuring the separator and electrodes maintain their structural integrity and uniformity during operation.
Data Source
AI summary
The present invention provides a nonaqueous electrolyte secondary battery having excellent battery characteristics, including a battery separator containing a polyolefin porous film; a positive electrode plate; and a negative electrode plate. The polyolefin porous film has a puncture strength of at least 26.0 gf/g/m2 and satisfies Formula (A), and the positive and negative electrode plates satisfy Formula (B).0.00≤|1−T/M|≤0.54 (A)0.00≤|1−T/M|≤0.50 (B)T represents a distance by which the polyolefin porous film or positive or negative electrode plate moves in a traverse direction from a starting point to a point where a critical load is obtained in a scratch test under a constant load of 0.1 N, and M represents a distance by which the porous film or positive or negative electrode plate moves in a machine direction from the starting point to the point where the critical load is obtained.