Nonaqueous Battery Electrode Stress Distribution via Segmented Current Collectors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in achieving higher output and capacity due to stress from wrap tape thickness and expansion-contraction, leading to crack formation in the negative electrode mixture, which worsens cycle retention rates.
Innovation Solution
The battery design includes a negative electrode with first and second current collector-exposed parts for improved electrical connection to the battery case, and a positive electrode with a strategically positioned current collector lead to distribute stress evenly, preventing cracks and enhancing circularity, thereby improving output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the diameter of the electrode body is increased to achieve higher capacity, then the capacity is improved, but the stress concentration and crack formation in the negative electrode mixture worsen
Solution Approach 1:
The negative electrode current collector is divided into multiple exposure parts (first and second current collector-exposed parts) at different radial positions. This segmentation allows multiple current collector leads to be connected at different locations, distributing the electrical connection points and reducing stress concentration at any single point during expansion-contraction cycles.
Solution Approach 2:
The patent positions the first and second current collector-exposed parts at different radial distances from the winding axis, creating an asymmetric current collector lead arrangement. This asymmetric positioning optimizes the distribution of mechanical stress during electrode expansion and contraction, preventing crack formation while maintaining high capacity.
2Stability of the object's composition
If a wrap tape is used to fix the electrode body, then the structural stability is improved, but the stress concentration and crack formation in the negative electrode mixture worsen
Solution Approach 1:
The wrap tape is positioned to fix the electrode body at specific locations that avoid the current collector-exposed parts. This segmentation of functional zones ensures that the wrap tape provides structural stability without creating stress concentration points at the critical current collector connection areas, preventing crack formation during cycling.
3Device complexity
If current is collected by connecting a current collector lead to the current collector-exposed part at the outermost periphery, then the electrical connection is simplified, but the output is insufficient due to current concentration
Solution Approach 1:
The current collection function is segmented into multiple current collector leads connected at different radial positions (first current collector-exposed part and second current collector-exposed part). This segmentation distributes the current collection across multiple points, increasing the total current collection area and improving output without significantly increasing connection complexity.
Solution Approach 2:
The patent transitions from a single-point current collection at the periphery to a distributed current collection system with leads positioned at different radial distances from the winding axis. This dimensional distribution of current collection points increases the effective current collection area and improves output capability.
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a negative electrode plate, a negative electrode current collector lead joined to the inner peripheral end of the negative electrode plate, and a negative electrode current collector-exposed part where a negative electrode active material layer is not formed at the outer peripheral-side end. The negative electrode current collector-exposed part at the outer peripheral end comes in contact with a battery case, and in a plane vertical to the axis of an electrode body, a line connecting the axis and the center of a positive electrode current collector lead does not coincide with a line connecting the axis and the center between the coating end of the outer peripheral-side negative electrode active material layer of the negative electrode plate and the terminal part of the outer peripheral-side positive electrode plate.