Lithium Battery Electrode Stack to Prevent Outermost Electrode Curling
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Solution Overview
Problem
Lithium batteries face defects during the manufacturing process of the electrode group stack, particularly due to bending and curling issues with the outermost electrodes, which affect energy density and assembly precision.
Innovation Solution
The lithium battery design includes an electrode group stack with a second positive or negative electrode having a thinner current collector and an interlayer between the current collector and active material layer, ensuring a single-sided configuration to reduce bending and enhance energy density, along with a dry mixing method for the active material layer preparation to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a double-sided electrode configuration is used in the outermost layer of the electrode group stack, then the energy density is improved, but the electrode is prone to bending and curling defects during manufacturing
Solution Approach 1:
The patent applies asymmetry by using a single-sided electrode configuration for the outermost layer instead of the conventional double-sided configuration. This asymmetric design (one side with active material, one side without) prevents bending and curling defects during manufacturing while maintaining high energy density through optimized electrode stack design
2Stability of the object's composition
If the current collector thickness is increased to reduce bending, then the structural stability is improved, but the energy density decreases
Solution Approach 1:
The patent applies local quality by using different current collector thicknesses for different electrode layers. The inner electrodes use thicker current collectors for stability, while the outermost single-sided electrode uses a thinner current collector to maximize energy density without compromising overall structural integrity
Solution Approach 2:
The patent changes the current collector thickness parameter based on the electrode's position in the stack. By optimizing the thickness parameter for each specific location (thinner for outermost, thicker for inner), the patent achieves both high energy density and sufficient structural stability
3Reliability
If an interlayer is added between the current collector and active material layer, then the defect generation is suppressed, but the device complexity increases
Solution Approach 1:
The patent introduces an interlayer as an intermediary component between the current collector and the active material layer in the outermost electrode. This interlayer acts as a mediator that prevents direct contact and reduces defects such as bending and curling during the roll-pressing process, while the overall structural complexity remains manageable
Data Source
AI summary
A lithium battery includes an electrode group stack i including a plurality of positive electrodes and one or more negative electrodes, wherein the plurality of positive electrodes includes a first and a second positive electrode, the first positive electrode being an inner layer, the second positive electrode being the outermost layer, and the first positive electrode including a first positive current collector and a first positive active material layer, wherein the first positive active material layer is on both surfaces of the first positive current collector, wherein the second positive electrode includes a second positive current collector, a second positive active material layer, and an interlayer between the second positive current collector and the second positive active material layer, the second positive current collector including a first surface and a second surface on opposite sides of the second positive current collector, wherein the first surface faces the inner layer.