Spiral-Wound Electrode Assembly with Radial Material Segmentation
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Solution Overview
Problem
Rechargeable lithium batteries experience non-uniform reactions due to varying electrode circumferences, leading to reduced cycle-life and potential issues like overcharging or overvoltage, which affect the battery's performance.
Innovation Solution
A spiral-wound electrode assembly is designed with a negative electrode and a positive electrode, each featuring composite materials with specific orientations and degrees of divergence, along with a separator, to ensure uniform reactions and improved cycle-life. The first composite material of the negative electrode is positioned farther from the center than the second, and similarly for the positive electrode, with the materials containing carbon-based active materials like artificial graphite and Si or Sn-based materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a jelly-roll electrode assembly is formed by repeatedly stacking electrodes and separators, then the battery structure is compact and energy density is high, but non-uniform reactions occur due to different circumferences from center to outer periphery
Solution Approach 1:
The patent applies local quality by varying the degree of divergence of composite materials at different radial positions within the electrode assembly. Specifically, the degree of divergence is set to be greater at the outer peripheral region compared to the inner peripheral region, creating non-uniform material properties that compensate for the non-uniform reaction conditions (different circumferences) at different locations. This ensures more uniform overall reaction across the entire electrode assembly.
2Reliability
If composite materials with high degree of divergence are used to improve reaction uniformity, then cycle-life increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the electrode assembly into different radial regions (inner peripheral region and outer peripheral region) with distinct degree of divergence values. This segmentation allows each region to be optimized independently for its specific reaction conditions, achieving overall reaction uniformity while using achievable manufacturing precision for each segment rather than requiring extreme precision across the entire assembly.
Data Source
AI summary
An exemplary embodiment of the present invention provides a spiral-wound electrode assembly including: a negative electrode and a positive electrode, each of which is configured to include a substrate, and a first composite material and a second composite material formed on opposite surfaces of the substrate; and a separator disposed between the negative electrode and the anode, wherein the first composite material of the negative electrode is disposed farther away from a center of the electrode assembly than the second composite material of the negative electrode, and the first composite material of the negative electrode is oriented with respect to a first surface of the substrate of the negative electrode.