EVA Sealing Tape for Cylindrical Battery Electrode Stability
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Solution Overview
Problem
Conventional sealing tapes for rechargeable lithium batteries fail to effectively prevent rotation and movement of the electrode assembly within the cylindrical battery case, leading to performance deterioration, and lack sufficient flame retardancy.
Innovation Solution
A novel sealing tape with a substrate layer made of ethylene vinyl acetate resin containing 5-15 wt% vinyl acetate-derived repeating units, which exhibits balanced longitudinal swelling rates between the adhesive and substrate layers upon electrolyte impregnation, forming a three-dimensional shape to fill gaps and provide flame retardancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a sealing tape with PET or PP substrate is used, then the substrate shows little change in thickness when impregnated with electrolyte solution, but the adhesive layer changes thickness and detaches from the electrode assembly
Solution Approach 1:
The patent changes the substrate material parameter from conventional PET/PP to ethylene vinyl acetate resin with specific vinyl acetate content (5-15 wt%). This material parameter change enables the substrate to swell when impregnated with electrolyte solution, matching the swelling rate of the adhesive layer and preventing detachment while maintaining structural stability.
Solution Approach 2:
The patent uses a composite structure consisting of ethylene vinyl acetate resin substrate combined with specific adhesive layers. This composite material system ensures that both substrate and adhesive layer swell at matched rates when exposed to electrolyte, maintaining their bonded state and preventing delamination.
2Ease of manufacture
If conventional sealing tapes are used, then they provide basic sealing function, but they fail to suppress rotation and movement of the electrode assembly inside the cylindrical battery case
Solution Approach 1:
The patent modifies the substrate material parameters by selecting ethylene vinyl acetate resin with controlled vinyl acetate content (5-15 wt%). This parameter optimization provides the right balance between manufacturing ease and functional performance, enabling the sealing tape to suppress electrode assembly rotation and movement while remaining manufacturable.
3Ease of manufacture
If conventional sealing tapes are used, then they provide basic sealing function, but they cannot suppress abnormal phenomena such as heat generation and ignition
Solution Approach 1:
The patent changes the substrate material from conventional options to ethylene vinyl acetate resin with specific vinyl acetate content (5-15 wt%). This material parameter selection provides inherent flame retardancy and heat resistance properties, suppressing abnormal phenomena like heat generation and ignition while maintaining ease of manufacture.
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 novel sealing tape effectively suppresses rotation and movement of the electrode assembly, enhances battery performance, and demonstrates excellent flame retardancy, preventing performance degradation and ensuring safety.
Implementation Method 1
the substrate layer and the adhesive layer have a balanced longitudinal swelling rate when impregnated with an electrolyte solution
Implementation Method 2
the novel sealing tape that effectively suppresses rotation and/or movement of the rolled electrode assembly while exhibiting flame retardancy
Data Source
AI summary
A sealing tape for a rechargeable lithium battery and a rechargeable lithium battery including the same are provided. The sealing tape includes a substrate layer and an adhesive layer on the substrate layer, wherein the substrate layer includes an ethylene vinyl acetate resin including an ethylene-derived repeating unit and a vinyl acetate-derived repeating unit, and based on 100 wt % of the ethylene vinyl acetate resin, a content (e.g., amount) of the repeating unit derived from the vinyl acetate is about 5 wt % to about 15 wt %.