Negative Electrode Plate Composition for Crack-Resistant Battery Winding
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Solution Overview
Problem
Secondary batteries face challenges in achieving high energy density while maintaining flexibility of electrode plates, as existing stacking and winding processes lead to cracking and reduced performance.
Innovation Solution
A negative electrode plate composition comprising 90.0% to 98.6% negative electrode active material, 1.0%-5.0% polymer binder, and 0.2%-4.0% toughening fiber, with a three-dimensional cross-linked network structure polymer binder and specific polar functional groups, enhances strength and flexibility, reducing cracking and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrode plates are made highly flexible to accommodate stacking and winding processes, then manufacturing feasibility is improved, but cracking occurs during bending which leads to battery core failure
Solution Approach 1:
The patent uses a composite material system consisting of polymer binder (acrylic acid-acrylonitrile copolymer) and toughening fiber (aramid fiber) in the negative electrode active material layer. This composite structure provides both flexibility for manufacturing processes and crack resistance for reliability, resolving the contradiction between ease of manufacture and battery core reliability.
Solution Approach 2:
The patent optimizes the content parameters of polymer binder (1.0%-5.0% by weight) and toughening fiber (0.2%-4.0% by weight) in the negative electrode active material layer. By controlling these parameter ranges, the electrode plate achieves appropriate flexibility for stacking/winding while maintaining sufficient strength to prevent cracking during processing.
2Strength
If polymer binder content is increased to enhance adhesion and strength, then electrode plate strength is improved, but energy density decreases due to higher non-active material content
Solution Approach 1:
The patent precisely controls the polymer binder content within 1.0%-5.0% by weight of the negative electrode active material layer. This parameter optimization ensures sufficient adhesion and strength while minimizing the proportion of non-active material, thereby maintaining high energy density.
Solution Approach 2:
The patent combines polymer binder with toughening fiber to create a composite reinforcement system. This allows the use of lower polymer binder content (reducing impact on energy density) while still achieving the required strength through the synergistic effect of both components.
3Stability of the object's composition
If toughening fiber content is increased to reduce cracking and improve flexibility, then electrode plate flexibility is improved, but manufacturing complexity increases
Solution Approach 1:
The patent controls toughening fiber content within 0.2%-4.0% by weight of the negative electrode active material layer. This parameter range provides sufficient flexibility and crack resistance while avoiding excessive fiber content that would complicate manufacturing processes.
Solution Approach 2:
The patent distributes toughening fiber uniformly throughout the negative electrode active material layer, ensuring localized reinforcement where needed without requiring complex manufacturing processes. The uniform distribution achieves flexibility improvement through simple mixing and coating operations.
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 solution improves the flexibility and energy density of secondary batteries by synergistically combining polymer binders and toughening fibers, resulting in better strength and reduced impedance, thus enhancing overall battery performance.
Implementation Method 1
The polymer binder with the three-dimensional cross-linked network structure has a better bonding property, which allows it to lock the negative electrode active material more effectively
Implementation Method 2
the negative electrode active material layer contains an appropriate amount of polymer binder and an appropriate amount of toughening fiber, which are synergistic with each other to reduce cracking of the negative electrode plate, thus achieving the effect of improving flexibility
Data Source
AI summary
Embodiments of the present application provide a negative electrode plate, a secondary battery, a battery module, a battery pack and an electrical device. The negative electrode plate may comprise a negative electrode current collector; and a negative electrode active material layer, wherein the negative electrode active material layer may be disposed on at least one surface of the negative electrode current collector, and comprise, based on total weight of the negative electrode active material layer, 90.0% to 98.6% by weight of a negative electrode active material; 1.0%-5.0% by weight of a polymer binder; and 0.2%-4.0% by weight of a toughening fiber.