Wound Secondary Battery Electrode Layout to Protect Separators
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Solution Overview
Problem
Conventional secondary batteries face stress concentration on separators due to external impacts, leading to potential breakage and short circuits at exposed current collector portions.
Innovation Solution
A secondary battery design with shifted insulating members covering positive electrode material layers, reducing the number of step portions and dispersing stress, thereby minimizing separator breakage and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tape ends of the insulating tape are arranged so as to be aligned in a thickness direction of the positive electrode, then the insulating tape can be simply manufactured, but stress concentrates on local portions of the separator when external force is applied, causing separator breakage and short circuits
Solution Approach 1:
The patent applies asymmetry by intentionally misaligning the ends of the first and second insulating tapes in the circumferential direction of the positive electrode. Instead of aligning both tape ends with the same positive electrode material layer end, the first insulating tape end is positioned at a different location than the second insulating tape end. This asymmetric arrangement prevents the formation of step portions that align in the thickness direction, thereby dispersing stress concentration points on the separator and preventing separator breakage under external impact.
2Device complexity
If insulating tape ends are aligned with positive electrode material layer ends in the thickness direction, then the structure is simplified, but stress concentration occurs on the separator leading to breakage
Solution Approach 1:
The patent introduces asymmetry in the positioning of insulating tape ends relative to the positive electrode material layer ends. The first insulating tape end is positioned at a different circumferential location than the second insulating tape end, creating an asymmetric configuration that avoids aligned step portions. This asymmetric arrangement effectively disperses stress concentration on the separator while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent applies local quality by creating different positioning relationships between insulating tapes and positive electrode material layers at different locations around the electrode assembly. Specifically, the first insulating tape is positioned differently relative to the positive electrode material layer compared to where the second insulating tape is positioned. This local variation in positioning prevents uniform stress concentration and protects the separator at critical locations.
Data Source
AI summary
A secondary battery is provided and including a wound electrode assembly in which a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode are wound; and an electrolyte, the wound electrode assembly and the electrolyte being enclosed in an exterior body, at least the positive electrode including a wound current collector, a first positive electrode material layer and a second positive electrode material layer provided on both surfaces of the current collector, and a pair of exposed portions including a first exposed portion in which one surface of a local portion of the current collector is exposed and a second exposed portion in which the other surface facing the one surface in a thickness direction of the positive electrode is exposed.