Positive Electrode Plate Adhesive Layer for Bent-Region Lithium Control
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Solution Overview
Problem
Lithium precipitation in batteries leads to reduced service life and safety hazards due to dendrite formation and potential short circuits.
Innovation Solution
A positive electrode plate with a method of preparation that includes forming an adhesive layer on the positive electrode current collector at to-be-bent positions, which reduces the positive electrode active material capacity in these regions, thereby minimizing lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode active material layer is uniformly formed across the entire current collector surface, then the energy density is maximized, but lithium precipitation occurs in bent regions reducing safety
Solution Approach 1:
The patent applies different properties to different parts of the positive electrode plate. Specifically, the bent position region has a reduced positive electrode active material layer thickness compared to the straight position region. This local differentiation ensures that in bent regions where lithium precipitation is more likely to occur, there is less positive electrode active material to release lithium ions, thereby reducing the risk of lithium precipitation and improving safety, while straight regions maintain full active material capacity for energy density.
2Reliability
If adhesive tape is used to reduce positive electrode active material in bent regions, then lithium precipitation is reduced, but the bonding surface is flat reducing adhesion effect
Solution Approach 1:
The patent changes the surface topology parameter of the adhesive layer from flat to uneven. The adhesive layer is designed with an uneven bonding surface that increases the contact area between the positive electrode active material and the adhesive layer. This uneven surface is achieved through the curing process of the adhesive liquid which creates a non-uniform topography, thereby enhancing the adhesion effect and improving the bonding strength between layers.
3Strength
If adhesive liquid is cured to form adhesive layer, then flexibility and adhesion are improved, but production time increases
Solution Approach 1:
The patent utilizes the phase transition of the adhesive liquid from liquid state to solid state through curing. This phase transition allows the adhesive to initially be in liquid form for easy application and coating, then transforms into a solid state with strong adhesion properties after curing. The curing process can be accelerated using UV irradiation or heat treatment, enabling the adhesive to quickly achieve full bonding strength while minimizing the time added to the production process.
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 effectively reduces or avoids lithium precipitation, enhancing the safety and service life of batteries while maintaining energy density.
Implementation Method 1
providing an adhesive liquid on at least one surface of at least partial to-be-bent position of the positive electrode current collector and curing it to form an adhesive layer
Data Source
AI summary
This application provides a positive electrode plate and a preparation method thereof, an electrode assembly, a battery cell, and a battery and pertains to the field of battery technologies. The method for preparing a positive electrode plate includes: providing an adhesive liquid on at least one surface of at least partial to-be-bent position of a positive electrode current collector and curing it to form an adhesive layer, and forming a positive electrode active material layer on at least one surface of the positive electrode current collector having the adhesive layer. The adhesive liquid is first provided on at least one surface of the to-be-bent position of the positive electrode current collector and cured to form the adhesive layer, and then the positive electrode active material layer is formed.