Battery Porous Membrane Composition Peel Strength
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Solution Overview
Problem
Conventional non-aqueous secondary battery porous membranes have limitations in terms of peel strength and output characteristics, necessitating improvements to enhance their performance.
Innovation Solution
A composition comprising inorganic particles, a binder with an aromatic vinyl monomer unit-containing polymer, and a surfactant, where the surfactant is present within a specific fractional content range, is used to form a porous membrane with improved peel strength and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a conventional binder containing a particulate polymer formed by a random copolymer including a (meth)acrylic acid alkyl ester monomer unit and an aromatic monovinyl monomer unit is used, then durability of the porous membrane is improved, but peel strength of the porous membrane is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by incorporating specific monomer units with defined proportions: a (meth)acrylic acid alkyl ester monomer unit (35-65 mass%), an aromatic monovinyl monomer unit (20-65 mass%), and a multifunctional monomer unit (0.1-5 mass%). This parameter optimization resolves the contradiction by achieving both improved durability and enhanced peel strength simultaneously.
Solution Approach 2:
The binder is designed as a composite polymer system combining multiple monomer units with different functions: the (meth)acrylic acid alkyl ester provides flexibility and adhesion, the aromatic monovinyl provides structural integrity, and the multifunctional monomer provides crosslinking for enhanced bonding. This composite approach resolves the contradiction between durability and peel strength.
2Strength
If a porous membrane is formed to improve heat resistance and strength, then protective function is enhanced, but output characteristics of the secondary battery deteriorate
Solution Approach 1:
The porous membrane is designed with spatially differentiated properties: it provides strong mechanical protection and heat resistance where needed, while maintaining local porosity and permeability in the bulk structure to allow efficient ion transport. This local quality differentiation resolves the contradiction between strength and output characteristics.
Solution Approach 2:
The membrane utilizes a porous structure with controlled pore size and distribution that provides mechanical strength through the polymer matrix while maintaining ion conductivity through the porous network. This porous material approach resolves the contradiction between strength and power output.
3Ease of manufacture
If a porous membrane is formed by drying an applied composition, then a protective layer is created, but foaming occurs and defects such as pinholes are generated
Solution Approach 1:
The composition is formulated with preliminary anti-foaming measures by incorporating specific additives and optimizing the binder composition before application. The binder's chemical structure and composition are designed in advance to minimize foaming tendency during the drying process, preventing defects before they occur.
Solution Approach 2:
The invention introduces intermediary substances (surfactants and additives) that mediate between the binder and the dispersion medium to prevent excessive foaming during application and drying. These intermediaries control surface tension and foam stability, resolving the contradiction between ease of manufacture and manufacturing precision.
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 composition effectively increases the peel strength of the porous membrane and enhances the output characteristics of non-aqueous secondary batteries, while inhibiting foaming and reducing defects such as pinholes, thereby improving battery performance.
Implementation Method 1
a surfactant, wherein a fractional content of the surfactant is not less than 0.25 parts by mass and not more than 5 parts by mass per 100 parts by mass of the inorganic particles
Implementation Method 2
a binder including a polymer including an aromatic vinyl monomer unit
Data Source
AI summary
Provided is a composition for a non-aqueous secondary battery porous membrane capable of forming a porous membrane having excellent peel strength and capable of providing a non-aqueous secondary battery having excellent output characteristics. The composition for a non-aqueous secondary battery porous membrane contains inorganic particles, a binder, a surfactant, and water. The binder includes a polymer including an aromatic vinyl monomer unit. Fractional content of the surfactant is not less than 0.25 parts by mass and not more than 5 parts by mass per 100 parts by mass of the inorganic particles.