Core-Shell Electrode Binder for Dense Slurry Adhesion
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Solution Overview
Problem
Existing binder compositions for electrochemical device electrodes fail to provide adequate peel strength, dusting resistance, and rate characteristics, especially when the electrode mixed material layer is densified and has increased basis weight.
Innovation Solution
A binder composition containing an organic solvent and a binder with a particulate polymer A having a core-shell structure and a polymer B with specific properties, including a glass-transition temperature range for the shell portion and a cyano group-containing monomer unit in the polymer B, is used to form an electrode mixed material layer with enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode mixed material layer is densified and basis weight is increased to increase capacity, then the capacity of the electrochemical device is improved, but the peel strength and dusting resistance of the electrode mixed material layer deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by incorporating specific polymers with defined glass transition temperatures and functional groups. The binder contains a polymer with glass transition temperature of -60°C to 0°C and another polymer containing cyano group-containing monomer units, with their ratios and molecular weights carefully controlled to achieve optimal adhesion in dense electrode structures
Solution Approach 2:
The invention uses a composite binder system combining multiple polymer components with complementary properties. The first polymer provides base binding functionality while the second polymer with cyano groups enhances adhesion to electrode active materials, creating a synergistic effect that maintains peel strength even when electrode density and basis weight are increased for higher capacity
2Quantity of substance
If the electrode mixed material layer is densified and basis weight is increased to increase capacity, then the capacity of the electrochemical device is improved, but the dusting resistance of the electrode mixed material layer deteriorates
Solution Approach 1:
The invention adjusts binder composition parameters including the glass transition temperature range (-60°C to 0°C) and the presence of cyano group-containing monomer units, which enhance intermolecular forces and adhesion. This ensures electrode active materials remain firmly bound even in high-density structures where dusting is more likely to occur during handling and operation
Solution Approach 2:
The composite binder system combines polymers with different functional characteristics, where the cyano group-containing polymer provides enhanced bonding strength and stability. This composite approach ensures reliable dusting resistance in high-capacity, high-density electrodes that undergo repeated charge-discharge cycles
3Ease of manufacture
If conventional binder composition is used to form electrode mixed material layer, then the manufacturing process is simple, but the rate characteristics of the electrochemical device are inadequate
Solution Approach 1:
The invention modifies binder parameters by incorporating polymers with specific glass transition temperatures (-60°C to 0°C) and cyano group-containing monomer units. These parameter changes enhance the binder's ability to facilitate rapid ion and electron transport, improving rate characteristics while maintaining compatibility with existing slurry preparation and coating processes
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 binder composition effectively increases the peel strength and dusting resistance of the electrode mixed material layer and enhances the rate characteristics of the electrochemical device, even at higher densities and basis weights.
Implementation Method 1
a polymer forming the shell portion has a glass-transition temperature of not lower than −50° C. and not higher than 20° C.
Implementation Method 2
strength of close adherence between components in the electrode mixed material layer
Data Source
AI summary
Provided is a binder composition for an electrochemical device electrode with which it is possible to form an electrode mixed material layer that has excellent peel strength and dusting resistance and that can cause an electrochemical device to display excellent rate characteristics. The binder composition for an electrochemical device electrode contains a binder and an organic solvent. The binder includes a particulate polymer A and a polymer B. The particulate polymer A has a core-shell structure including a core portion and a shell portion at least partially covering an outer surface of the core portion, and a polymer forming the shell portion has a glass-transition temperature of −50° C. to 20° C. A mixture obtained by mixing the polymer B in a concentration of 8 mass % with the organic solvent has a viscosity at a shear rate of 1 s−1 of 100 mPa·s to 10,000 mPa·s.