Polyvinylidene Fluoride Particle Separator for Battery Adhesion
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Solution Overview
Problem
Conventional separators for non-aqueous secondary batteries face challenges in maintaining ion permeability and adhesive properties due to the degradation of the porous structure of polyvinylidene fluoride resin layers under high temperature or pressure conditions, leading to insufficient battery characteristics and adhesion issues with electrodes.
Innovation Solution
A separator with an adhesive layer composed of polyvinylidene fluoride resin particles of specific size and distribution on a polyolefin microporous membrane, ensuring excellent adhesion and ion permeability, is developed, along with a method of coating a water-based dispersion to form an aggregate layer on both sides of the porous substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If compression bonding or heat pressing is performed under higher temperature conditions or pressure conditions to improve adhesive property, then adhesive property between electrode and separator is improved, but porous structure of polyvinylidene fluoride resin layer degrades and ion permeability becomes insufficient
Solution Approach 1:
The invention changes the physical and chemical parameters of the adhesive layer by controlling the particle size distribution (bimodal or multimodal distribution with specific diameter ranges), resin content (0.1-6.0 g/m²), and pore structure characteristics. This allows achieving sufficient adhesive strength without applying excessive heat or pressure that would degrade the porous structure and reduce ion permeability.
Solution Approach 2:
The invention uses a composite structure combining polyolefin microporous membrane substrate with polyvinylidene fluoride resin particle adhesive layer. This composite design enables the separator to simultaneously provide mechanical support, ion transport pathways, and adhesive bonding functionality without requiring high-temperature or high-pressure processing that would compromise any single function.
2Strength
If polyvinylidene fluoride resin layer is used to ensure adhesive property, then adhesive property between electrode and separator is improved, but handling property during battery production deteriorates
Solution Approach 1:
The invention applies local quality by creating an adhesive layer with specific particle size distribution and resin content optimized for adhesion, while maintaining the bulk separator's smooth surface and porous structure for good handling properties. The adhesive functionality is localized to the separator surface rather than the entire structure.
Solution Approach 2:
The invention uses a porous adhesive layer structure with controlled pore size and distribution that provides both adhesive strength and flexibility. The porous nature allows the layer to conform to electrode surfaces while maintaining handling ease during battery assembly operations.
3Strength
If adhesive layer with sufficient resin content is formed to improve adhesion, then adhesive property is improved, but ion permeability becomes insufficient
Solution Approach 1:
The invention optimizes the resin content parameter within a specific range (0.1-6.0 g/m²) and controls particle size distribution to achieve the right balance between adhesion and ion permeability. This parameter optimization ensures sufficient adhesive strength while maintaining adequate pore structure for ion transport.
Solution Approach 2:
The invention employs a porous adhesive layer structure where the resin particles are arranged to maintain interconnected pores throughout the layer. This porous configuration allows ions to permeate through the adhesive layer while the resin particles provide adhesive bonding to the electrode surface.
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 provides a non-aqueous secondary battery with enhanced adhesion to electrodes, improved ion permeability, and high energy density, while maintaining favorable cycle characteristics and handling properties.
Implementation Method 1
the porous layer adheres to the binder resin that binds active substances in the electrode
Implementation Method 2
achieve a balance between ion permeability and adhesive strength
Data Source
AI summary
The present invention provides a separator for a non-aqueous secondary battery including a porous substrate and an adhesive layer that is formed on at least one side of the porous substrate and is an aggregate layer of particles that contain a polyvinylidene fluoride resin and have an average particle diameter of from 0.01 μm to 1 μm, in which a content of the particles per one adhesive layer is from 0.1 g/m2 to 6.0 g/m2.