Secondary Battery Binder Composition for Heat Shrinkage and Adhesion
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Solution Overview
Problem
Conventional binders for secondary battery functional layers face challenges in achieving excellent heat shrinkage resistance, adhesiveness, and preservation stability.
Innovation Solution
A binder comprising a particulate polymer with specific chemical composition, including an acidic functional group-containing monomer unit and a reactive functional group-containing monomer unit, with a proportional content of the reactive functional group-containing monomer unit between 7 mass% and 30 mass%, and a film formed from the polymer having an elastic modulus of 10 MPa or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional binder containing a particulate polymer with specific monomer units is used, then adhesiveness before electrolyte immersion is improved, but heat shrinkage resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the proportional content of the reactive functional group-containing monomer unit within 7-30 mass% and adjusting the film elastic modulus to 10 MPa or less. This optimization of chemical composition parameters enables the binder to achieve both improved adhesiveness and heat shrinkage resistance simultaneously, resolving the technical contradiction between these two properties.
Solution Approach 2:
The patent employs composite materials by creating a particulate polymer that combines multiple monomer units with different functions: acidic functional group-containing monomer units for adhesion, reactive functional group-containing monomer units for crosslinking, and other functional monomer units. This composite polymer structure integrates the beneficial properties of different monomer components to achieve both strong adhesiveness and heat shrinkage resistance.
2Temperature
If the proportional content of reactive functional group-containing monomer unit is increased to improve heat shrinkage resistance, then adhesiveness may be compromised
Solution Approach 1:
The patent resolves this contradiction through parameter optimization by establishing the specific range of 7-30 mass% for the reactive functional group-containing monomer unit. This controlled parameter adjustment ensures sufficient crosslinking density for heat shrinkage resistance while maintaining adequate adhesive functionality, preventing either property from being compromised.
3Strength
If a binder is designed to achieve excellent initial adhesiveness and heat shrinkage resistance, then preservation stability over time may deteriorate
Solution Approach 1:
The patent applies preliminary action by incorporating the reactive functional group-containing monomer unit that undergoes crosslinking reactions during battery assembly and initial charging cycles. This preliminary crosslinking action creates a stable three-dimensional network structure that locks in the adhesive and heat shrinkage properties, preventing their deterioration over time and ensuring long-term preservation stability.
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 binder forms a functional layer with enhanced heat shrinkage resistance, adhesiveness, and preservation stability, maintaining these properties over time.
Implementation Method 1
a reactive functional group-containing monomer unit including a functional group that can react with an acidic functional group
Implementation Method 2
a degree of swelling in non-aqueous electrolyte solution that is within a specific range
Data Source
AI summary
Provided is a binder for a secondary battery functional layer that can form a functional layer having excellent heat shrinkage resistance, adhesiveness, and preservation stability. The binder for a secondary battery functional layer contains a particulate polymer including an acidic functional group-containing monomer unit and a reactive functional group-containing monomer unit including a functional group that can react with an acidic functional group. The proportional content of the reactive functional group-containing monomer unit is not less than 7 mass% and not more than 30 mass% when all monomer units included in the particulate polymer are taken to be 100 mass%. A film that is formed of the particulate polymer after accelerated testing has an elastic modulus of 10 MPa or less.