PVDF Adhesive Porous Layer for Battery Separator
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Solution Overview
Problem
Existing nonaqueous secondary battery separators face challenges in achieving sufficient adhesion to electrodes and ion permeability, especially when subjected to severe heat pressing conditions, which can destroy the porous structure of the adhesive porous layer, leading to reduced cycle life and energy density.
Innovation Solution
A separator with a porous substrate and an adhesive porous layer made of polyvinylidene-fluoride-based resin, characterized by a porosity of 30-60% and average pore size of 1-100 nm, applied on both sides of the substrate, ensuring better adhesion and dynamic physical properties to withstand heat pressing while maintaining ion permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat pressing is performed under severe conditions to ensure sufficient adhesion, then adhesion strength is improved, but the porous structure of the adhesive porous layer is destroyed
Solution Approach 1:
The invention changes the physical and chemical parameters of the adhesive porous layer, specifically controlling porosity (30-80%) and average pore size (0.01-10 μm), to achieve optimal balance between adhesion and ion permeability without requiring severe heat pressing conditions
Solution Approach 2:
The invention uses a composite structure consisting of a polyolefin microporous membrane and an adhesive porous layer made of polyvinylidene-fluoride-based resin, combining the advantages of both materials to achieve sufficient adhesion while maintaining ion permeability
2Reliability
If the porous structure of the adhesive porous layer is maintained to ensure ion permeability, then ion permeability is improved, but adhesion strength is reduced
Solution Approach 1:
The invention optimizes the porosity parameter to 30-80% and average pore size to 0.01-10 μm, creating a porous structure that maintains ion permeability while providing sufficient adhesion through the specific surface area and pore distribution
3Strength
If the amount of binder resin in the electrode is increased to ensure sufficient adhesion, then adhesion strength is improved, but energy density is reduced
Solution Approach 1:
The adhesive porous layer acts as an intermediary between the electrode and separator, providing adhesion function without requiring increased binder resin content in the electrode, thus maintaining energy density while ensuring sufficient adhesion
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 separator provides improved adhesion to electrodes, sustained ion permeability, and enhanced cycle characteristics, enabling the production of high-energy-density, high-performance nonaqueous secondary batteries with an aluminum laminate pack outer casing.
Implementation Method 1
When such an adhesive porous layer with an electrolyte contained therein is stacked on an electrode and heat-pressed, the electrode and the separator can be well joined together
Implementation Method 2
the adhesive porous layer has a porosity of 30% or more and 60% or less and an average pore size of 1 nm or more and 100 nm or less
Data Source
AI summary
An object of the invention is to provide a separator for a nonaqueous secondary battery, which has good adhesion to electrodes, is capable of ensuring sufficient ion permeability even after attachment to electrodes, and further includes an adhesive porous layer having dynamic physical properties sufficient to withstand heat pressing and a uniform porous structure. The separator for a nonaqueous secondary battery of the invention includes a porous substrate and an adhesive porous layer that is formed on at least one side of the porous substrate and contains a polyvinylidene-fluoride-based resin. The separator for a nonaqueous secondary battery is characterized in that the adhesive porous layer has a porosity of 30 to 60% and an average pore size of 1 to 100 nm.