Composite Binder for Secondary Battery Adhesion
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Solution Overview
Problem
Conventional binders for secondary battery electrodes fail to provide sufficient adhesion force and structural stability, leading to decreased cycle life and capacity due to separation of electrode active materials and current collectors during charging and discharging.
Innovation Solution
A binder comprising polymer particles obtained by polymerizing three or more kinds of monomers with a mean particle diameter of 0.5 µm to 0.7 µm, specifically a mixture of (meth)acrylic acid ester, acrylate, vinyl, and unsaturated monocarbonic acid monomers, which enhances adhesion and support force even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders (PVdF or SBR) are used, then environmental friendliness or adhesion maintenance is improved, but adhesion force and structural stability are insufficient
Solution Approach 1:
The patent uses a composite binder system combining polyacrylic acid and polyvinyl alcohol in specific ratios (95:5 to 5:95), creating a composite material that leverages the strong adhesion of polyacrylic acid and the structural stability of polyvinyl alcohol to achieve both high adhesion force and structural stability
Solution Approach 2:
The patent optimizes the molecular weight parameters of the binder components (polyacrylic acid: 100,000-1,000,000; polyvinyl alcohol: 50,000-500,000) and their ratio to achieve the desired balance between adhesion force and structural stability, demonstrating parameter optimization to resolve the contradiction
2Quantity of substance
If electrode active materials with high discharge capacity (silicon, tin, silicon-tin alloys) are used, then discharge capacity is improved, but volume expansion causes isolation of anode material from current collector
Solution Approach 1:
The patent applies a binder coating beforehand on the current collector before depositing the electrode active material. This pre-applied binder layer acts as a cushioning interface that maintains adhesion even when the underlying active material undergoes significant volume expansion during charging-discharging cycles, preventing isolation from the current collector
Solution Approach 2:
The patent optimizes the molecular weight and ratio of binder components to create a binder with appropriate mechanical properties that can accommodate volume changes of high-capacity active materials while maintaining structural stability and adhesion
3Ease of manufacture
If binder particle size is reduced to improve mixing, then adhesion force decreases due to insufficient support at high temperatures
Solution Approach 1:
The patent specifies optimal molecular weight ranges for the binder components (polyacrylic acid: 100,000-1,000,000; polyvinyl alcohol: 50,000-500,000) to achieve the right balance between processability for uniform mixing and thermal stability for maintaining adhesion force at high temperatures during battery operation
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 significantly improves cycle properties and adhesion force to electrode current collectors, maintaining structural stability and performance of secondary batteries during repeated charging and discharging.
Implementation Method 1
the binder for secondary battery electrodes comprises polymer particles obtained by polymerizing three or more kinds of monomers wherein the polymer particles have a mean particle diameter of 0.5 μm to 0.7 μm... superior adhesion force to electrode current collectors
Data Source
AI summary
Provided is a binder for secondary battery electrodes comprising polymer particles obtained by polymerizing three or more kinds of monomers wherein the polymer particles have a mean particle diameter of 0.3 µm to 0.7 µm. The binder exhibits superior adhesion force to electrode current collectors and excellent support force to the active material and basically improves safety of electrodes, thus providing a secondary battery with superior cycle characteristics.