Laminated Separator Gloss Control for Battery Rate Characteristics
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Solution Overview
Problem
Existing nonaqueous electrolyte secondary battery separators, particularly those with polyolefin-based and polyvinylidene fluoride-based resin components, face challenges in improving rate characteristics due to limitations in adhesiveness and ion permeability, which are not adequately addressed by existing techniques.
Innovation Solution
A laminated separator design featuring a porous film with a polyolefin-based resin and a porous layer containing polyvinylidene fluoride-based resin, with a 60-degree specular gloss within a specific range (3% to 26%), and a filler proportion of 1% to 30% by mass, to enhance rate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a porous layer containing polyvinylidene fluoride-based resin is laminated on a porous film to improve adhesiveness between separator and electrode, then adhesiveness is improved, but ion permeability deteriorates
Solution Approach 1:
The patent applies porous materials by forming a porous layer containing polyvinylidene fluoride-based resin on the porous film. The porous structure allows ion permeability to be maintained while the resin provides adhesiveness to the electrode, resolving the contradiction between improved adhesiveness and deteriorated ion permeability.
Solution Approach 2:
The patent uses composite materials by combining polyvinylidene fluoride-based resin with inorganic fillers (such as氧化铝, 氧化镁, 氧化钛) in the porous layer. This composite structure enhances both adhesiveness and ion permeability simultaneously, as the inorganic fillers provide ion conduction pathways while the resin ensures proper adhesion to the electrode.
2Reliability
If filler proportion in porous layer is increased to improve ion permeability, then ion permeability is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the filler proportion within a specific range (1% to 30% by mass relative to total porous layer weight) and controlling the average particle size of fillers (0.1 μm to 5 μm). These parameter optimizations improve ion permeability while maintaining manufacturing precision and uniformity of the porous layer.
3Device complexity
If separator structure is simplified to reduce device complexity, then device complexity is reduced, but rate characteristic deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the separator into two functional layers: a porous film base layer providing mechanical strength and shutdown function, and a porous layer containing polyvinylidene fluoride-based resin and inorganic fillers providing enhanced ion permeability and adhesiveness. This segmented structure improves rate characteristic without excessive complexity.
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 proposed solution improves the rate characteristic of nonaqueous electrolyte secondary batteries by optimizing ion permeability and adhesiveness, preventing excessive current flow and heat generation, thereby ensuring better safety and performance.
Implementation Method 1
a 60-degree specular gloss of the porous layer is 3% to 26%
Data Source
AI summary
A laminated separator for a nonaqueous electrolyte secondary battery, (i) includes a porous film and a porous layer containing a polyvinylidene fluoride-based resin and (ii) has an excellent rate characteristic. The laminated separator includes the porous film containing a polyolefin-based resin as a main component and the porous layer containing the polyvinylidene fluoride-based resin, in which a surface of the porous layer has a 60-degree specular gloss of 3% to 26%.