Laminated Battery Separator Structure to Prevent Winding Adhesion
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Solution Overview
Problem
Conventional nonaqueous electrolyte secondary battery laminated separators often experience adhesion issues due to excessive adhesiveness, leading to compression and subsequent adhesion of overlapping separators during the winding process.
Innovation Solution
A laminated separator design featuring a heat-resistant layer with an inorganic filler proportion not exceeding 70% by weight, combined with a polyolefin-based base material and a particle layer containing thermoplastic resin particles with an average diameter between 0.1 μm and 3.0 μm, to reduce adhesion between separators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesiveness is imparted to the separator to improve bonding, then adhesion of overlapping separators occurs during winding
Solution Approach 1:
The invention applies different functional properties to different regions of the separator structure. The particle layer is positioned only on one or both surfaces of the separator, creating a local adhesive zone that bonds electrodes to the separator without causing overlapping separators to adhere. This localized application of adhesiveness prevents the harmful adhesion between stacked separators while maintaining necessary bonding strength where required.
Solution Approach 2:
The separator is constructed as a composite structure combining a base separator material with a particle layer containing thermoplastic resin particles. This composite configuration provides both the mechanical strength of the base material and the controlled adhesive properties of the particle layer, enabling the separator to bond electrodes effectively while preventing adhesion between overlapping separators during the winding process.
2Temperature
If inorganic filler proportion in heat-resistant layer is increased to improve heat resistance, then adhesion of separators is reduced
Solution Approach 1:
The invention optimizes the proportion of inorganic filler in the heat-resistant layer to fall within a specific range (20-70 wt%). This parameter optimization ensures that the heat-resistant layer maintains sufficient heat resistance for battery operation while its adhesive properties remain controlled. By precisely controlling this compositional parameter, the invention achieves both adequate thermal performance and prevention of separator adhesion during winding.
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 configuration effectively minimizes the occurrence of separator adhesion, enhancing the reliability and performance of nonaqueous electrolyte secondary batteries by controlling the compression and adhesiveness of the separator layers.
Implementation Method 1
particles contained in the particle layer containing a thermoplastic resin
Implementation Method 2
the heat-resistant layer containing an inorganic filler at a proportion of not more than 70% by weight
Data Source
AI summary
Provided is a laminated separator which makes it possible to reduce occurrence of adhesion of separators. A laminated separator (4a) has a heat-resistant layer (2a, 2b) on one surface or both surfaces of a polyolefin-based base material (1), the laminated separator including a particle layer (3a, 3b) on at least one side of the laminated separator, particles contained in the particle layer containing a thermoplastic resin, an average particle diameter of the particles being not less than 0.1 μm and less than 3.0 μm, and the heat-resistant layer containing an inorganic filler at a proportion of not more than 70% by weight.