Secondary Battery Anode Binder Composition for Warping Control
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Solution Overview
Problem
Non-fluoropolymer binders containing unsaturated carboxylic acid monomers face limitations such as a narrow processing window and difficulty in meeting the requirements of high-performance active materials, leading to issues like warping and edge cracking during the electrode plate manufacturing process.
Innovation Solution
A polymer comprising structural units derived from unsaturated carboxylic acid, unsaturated cyano, and flexible monomers, with a glass transition temperature of −60° C. to 0° C., which improves water solubility, ion transmission, and bonding strength, while reducing warping and stress concentration during the slurry drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a non-fluoropolymer binder containing an unsaturated carboxylic acid monomer is used, then the bonding force and water solubility are improved, but the processing window becomes narrow and warping occurs during the slurry drying process
Solution Approach 1:
The patent uses a composite polymer binder containing three types of structural units: unsaturated carboxylic acid units (for bonding strength), unsaturated cyano units (for adhesion to current collector), and flexible monomer units (for processing stability). This composite structure combines the advantages of different monomer types while mitigating their individual drawbacks, particularly the warping issue during drying.
Solution Approach 2:
The patent specifies a glass transition temperature range of -60°C to 0°C for the flexible monomer component, which fundamentally changes the thermal-mechanical properties of the binder. This parameter control ensures the binder remains flexible during the slurry drying process, preventing warping while maintaining bonding strength.
2Quantity of substance
If a non-fluoropolymer binder containing an unsaturated carboxylic acid monomer is used, then the water solubility is improved, but the processing window becomes narrow and edge cracking occurs
Solution Approach 1:
The composite polymer binder combines hydrophilic unsaturated carboxylic acid units (improving water solubility) with flexible monomer units having low glass transition temperature. This combination maintains excellent water solubility while the flexible component prevents processing issues like edge cracking during manufacturing.
Solution Approach 2:
By controlling the glass transition temperature of the flexible monomer component within -60°C to 0°C, the patent modifies the rheological properties of the slurry during processing, enabling better flow and distribution characteristics that widen the processing window while maintaining water solubility benefits.
3Shape
If the glass transition temperature of the polymer is lowered to improve flexibility, then the warping phenomenon is reduced, but the bonding strength may be compromised
Solution Approach 1:
The patent creates a composite binder where flexible monomer units (providing low glass transition temperature and flexibility) are combined with unsaturated carboxylic acid units (providing bonding strength through carboxyl groups) and unsaturated cyano units (providing adhesion to current collector). This composite structure ensures that flexibility improvement does not compromise bonding strength.
Solution Approach 2:
Different structural units in the polymer serve different local functions: the flexible monomer units specifically address warping and flexibility requirements, while the unsaturated carboxylic acid and cyano units maintain bonding and adhesion functions. This functional segmentation within the single polymer chain allows independent optimization of each property.
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 polymer enhances the flexibility and processability of the electrode plate, reducing warping and edge cracking, thereby improving the cycle stability and production efficiency of secondary batteries.
Implementation Method 1
A glass transition temperature of the flexible monomer is −60° C. to 0° C., and optionally −55° C. to −15° C.
Implementation Method 2
The containing of the structural unit derived from the unsaturated carboxylic acid monomer in the polymer can improve the water solubility of the polymer, and provide an ion transmission channel for lithium ions
Implementation Method 3
The containing of the structural unit derived from the unsaturated cyano monomer in the polymer can improve the bonding strength between the polymer and an active material as well as a current collector
Data Source
AI summary
The present application provides a polymer, a preparation method, a negative electrode plate, a secondary battery, and a power consuming apparatus. The polymer contains a structural unit derived from an unsaturated carboxylic acid monomer, a structural unit derived from an unsaturated cyano monomer, and a structural unit derived from a flexible monomer. The glass transition temperature of the flexible monomer is −60° C. to 0° C., and optionally −55° C. to −15° C.